Merge branch 'master' into for-next

1 files changed, 916 insertions, 331 deletions

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 4dade6ac0827..5ac0bb465ed6 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -33,6 +33,7 @@
 #include <asm/kvm_emulate.h>
 
 #include "x86.h"
+#include "tss.h"
 
 /*
  * Opcode effective-address decode tables.
@@ -50,6 +51,8 @@
 #define DstReg      (2<<1)      /* Register operand. */
 #define DstMem      (3<<1)      /* Memory operand. */
 #define DstAcc      (4<<1)      /* Destination Accumulator */
+#define DstDI       (5<<1)      /* Destination is in ES:(E)DI */
+#define DstMem64    (6<<1)      /* 64bit memory operand */
 #define DstMask     (7<<1)
 /* Source operand type. */
 #define SrcNone     (0<<4)      /* No source operand. */
@@ -63,6 +66,7 @@
 #define SrcOne      (7<<4)      /* Implied '1' */
 #define SrcImmUByte (8<<4)      /* 8-bit unsigned immediate operand. */
 #define SrcImmU     (9<<4)      /* Immediate operand, unsigned */
+#define SrcSI       (0xa<<4)    /* Source is in the DS:RSI */
 #define SrcMask     (0xf<<4)
 /* Generic ModRM decode. */
 #define ModRM       (1<<8)
@@ -85,6 +89,9 @@
 #define Src2ImmByte (2<<29)
 #define Src2One     (3<<29)
 #define Src2Imm16   (4<<29)
+#define Src2Mem16   (5<<29) /* Used for Ep encoding. First argument has to be
+                               in memory and second argument is located
+                               immediately after the first one in memory. */
 #define Src2Mask    (7<<29)
 
 enum {
@@ -147,8 +154,8 @@ static u32 opcode_table[256] = {
         0, 0, 0, 0,
         /* 0x68 - 0x6F */
         SrcImm | Mov | Stack, 0, SrcImmByte | Mov | Stack, 0,
-        SrcNone  | ByteOp  | ImplicitOps, SrcNone  | ImplicitOps, /* insb, insw/insd */
-        SrcNone  | ByteOp  | ImplicitOps, SrcNone  | ImplicitOps, /* outsb, outsw/outsd */
+        DstDI | ByteOp | Mov | String, DstDI | Mov | String, /* insb, insw/insd */
+        SrcSI | ByteOp | ImplicitOps | String, SrcSI | ImplicitOps | String, /* outsb, outsw/outsd */
         /* 0x70 - 0x77 */
         SrcImmByte, SrcImmByte, SrcImmByte, SrcImmByte,
         SrcImmByte, SrcImmByte, SrcImmByte, SrcImmByte,
@@ -173,12 +180,12 @@ static u32 opcode_table[256] = {
         /* 0xA0 - 0xA7 */
         ByteOp | DstReg | SrcMem | Mov | MemAbs, DstReg | SrcMem | Mov | MemAbs,
         ByteOp | DstMem | SrcReg | Mov | MemAbs, DstMem | SrcReg | Mov | MemAbs,
-        ByteOp | ImplicitOps | Mov | String, ImplicitOps | Mov | String,
-        ByteOp | ImplicitOps | String, ImplicitOps | String,
+        ByteOp | SrcSI | DstDI | Mov | String, SrcSI | DstDI | Mov | String,
+        ByteOp | SrcSI | DstDI | String, SrcSI | DstDI | String,
         /* 0xA8 - 0xAF */
-        0, 0, ByteOp | ImplicitOps | Mov | String, ImplicitOps | Mov | String,
-        ByteOp | ImplicitOps | Mov | String, ImplicitOps | Mov | String,
-        ByteOp | ImplicitOps | String, ImplicitOps | String,
+        0, 0, ByteOp | DstDI | Mov | String, DstDI | Mov | String,
+        ByteOp | SrcSI | DstAcc | Mov | String, SrcSI | DstAcc | Mov | String,
+        ByteOp | DstDI | String, DstDI | String,
         /* 0xB0 - 0xB7 */
         ByteOp | DstReg | SrcImm | Mov, ByteOp | DstReg | SrcImm | Mov,
         ByteOp | DstReg | SrcImm | Mov, ByteOp | DstReg | SrcImm | Mov,
@@ -204,13 +211,13 @@ static u32 opcode_table[256] = {
         0, 0, 0, 0, 0, 0, 0, 0,
         /* 0xE0 - 0xE7 */
         0, 0, 0, 0,
-        ByteOp | SrcImmUByte, SrcImmUByte,
-        ByteOp | SrcImmUByte, SrcImmUByte,
+        ByteOp | SrcImmUByte | DstAcc, SrcImmUByte | DstAcc,
+        ByteOp | SrcImmUByte | DstAcc, SrcImmUByte | DstAcc,
         /* 0xE8 - 0xEF */
         SrcImm | Stack, SrcImm | ImplicitOps,
         SrcImmU | Src2Imm16 | No64, SrcImmByte | ImplicitOps,
-        SrcNone | ByteOp | ImplicitOps, SrcNone | ImplicitOps,
-        SrcNone | ByteOp | ImplicitOps, SrcNone | ImplicitOps,
+        SrcNone | ByteOp | DstAcc, SrcNone | DstAcc,
+        SrcNone | ByteOp | DstAcc, SrcNone | DstAcc,
         /* 0xF0 - 0xF7 */
         0, 0, 0, 0,
         ImplicitOps | Priv, ImplicitOps, Group | Group3_Byte, Group | Group3,
@@ -343,7 +350,8 @@ static u32 group_table[] = {
         [Group5*8] =
         DstMem | SrcNone | ModRM, DstMem | SrcNone | ModRM,
         SrcMem | ModRM | Stack, 0,
-        SrcMem | ModRM | Stack, 0, SrcMem | ModRM | Stack, 0,
+        SrcMem | ModRM | Stack, SrcMem | ModRM | Src2Mem16 | ImplicitOps,
+        SrcMem | ModRM | Stack, 0,
         [Group7*8] =
         0, 0, ModRM | SrcMem | Priv, ModRM | SrcMem | Priv,
         SrcNone | ModRM | DstMem | Mov, 0,
@@ -353,14 +361,14 @@ static u32 group_table[] = {
         DstMem | SrcImmByte | ModRM, DstMem | SrcImmByte | ModRM | Lock,
         DstMem | SrcImmByte | ModRM | Lock, DstMem | SrcImmByte | ModRM | Lock,
         [Group9*8] =
-        0, ImplicitOps | ModRM | Lock, 0, 0, 0, 0, 0, 0,
+        0, DstMem64 | ModRM | Lock, 0, 0, 0, 0, 0, 0,
 };
 
 static u32 group2_table[] = {
         [Group7*8] =
-        SrcNone | ModRM | Priv, 0, 0, SrcNone | ModRM,
+        SrcNone | ModRM | Priv, 0, 0, SrcNone | ModRM | Priv,
         SrcNone | ModRM | DstMem | Mov, 0,
-        SrcMem16 | ModRM | Mov, 0,
+        SrcMem16 | ModRM | Mov | Priv, 0,
         [Group9*8] =
         0, 0, 0, 0, 0, 0, 0, 0,
 };
@@ -562,7 +570,7 @@ static u32 group2_table[] = {
 #define insn_fetch(_type, _size, _eip)                                  \
 ({      unsigned long _x;                                               \
         rc = do_insn_fetch(ctxt, ops, (_eip), &_x, (_size));            \
-        if (rc != 0)                                                    \
+        if (rc != X86EMUL_CONTINUE)                                     \
                 goto done;                                              \
         (_eip) += (_size);                                              \
         (_type)_x;                                                      \
@@ -638,40 +646,40 @@ static unsigned long ss_base(struct x86_emulate_ctxt *ctxt)
 
 static int do_fetch_insn_byte(struct x86_emulate_ctxt *ctxt,
                               struct x86_emulate_ops *ops,
-                              unsigned long linear, u8 *dest)
+                              unsigned long eip, u8 *dest)
 {
         struct fetch_cache *fc = &ctxt->decode.fetch;
         int rc;
-        int size;
+        int size, cur_size;
 
-        if (linear < fc->start || linear >= fc->end) {
-                size = min(15UL, PAGE_SIZE - offset_in_page(linear));
-                rc = ops->fetch(linear, fc->data, size, ctxt->vcpu, NULL);
-                if (rc)
+        if (eip == fc->end) {
+                cur_size = fc->end - fc->start;
+                size = min(15UL - cur_size, PAGE_SIZE - offset_in_page(eip));
+                rc = ops->fetch(ctxt->cs_base + eip, fc->data + cur_size,
+                                size, ctxt->vcpu, NULL);
+                if (rc != X86EMUL_CONTINUE)
                         return rc;
-                fc->start = linear;
-                fc->end = linear + size;
+                fc->end += size;
         }
-        *dest = fc->data[linear - fc->start];
-        return 0;
+        *dest = fc->data[eip - fc->start];
+        return X86EMUL_CONTINUE;
 }
 
 static int do_insn_fetch(struct x86_emulate_ctxt *ctxt,
                          struct x86_emulate_ops *ops,
                          unsigned long eip, void *dest, unsigned size)
 {
-        int rc = 0;
+        int rc;
 
         /* x86 instructions are limited to 15 bytes. */
-        if (eip + size - ctxt->decode.eip_orig > 15)
+        if (eip + size - ctxt->eip > 15)
                 return X86EMUL_UNHANDLEABLE;
-        eip += ctxt->cs_base;
         while (size--) {
                 rc = do_fetch_insn_byte(ctxt, ops, eip++, dest++);
-                if (rc)
+                if (rc != X86EMUL_CONTINUE)
                         return rc;
         }
-        return 0;
+        return X86EMUL_CONTINUE;
 }
 
 /*
@@ -702,7 +710,7 @@ static int read_descriptor(struct x86_emulate_ctxt *ctxt,
         *address = 0;
         rc = ops->read_std((unsigned long)ptr, (unsigned long *)size, 2,
                            ctxt->vcpu, NULL);
-        if (rc)
+        if (rc != X86EMUL_CONTINUE)
                 return rc;
         rc = ops->read_std((unsigned long)ptr + 2, address, op_bytes,
                            ctxt->vcpu, NULL);
@@ -782,7 +790,7 @@ static int decode_modrm(struct x86_emulate_ctxt *ctxt,
         struct decode_cache *c = &ctxt->decode;
         u8 sib;
         int index_reg = 0, base_reg = 0, scale;
-        int rc = 0;
+        int rc = X86EMUL_CONTINUE;
 
         if (c->rex_prefix) {
                 c->modrm_reg = (c->rex_prefix & 4) << 1;        /* REX.R */
@@ -895,7 +903,7 @@ static int decode_abs(struct x86_emulate_ctxt *ctxt,
                       struct x86_emulate_ops *ops)
 {
         struct decode_cache *c = &ctxt->decode;
-        int rc = 0;
+        int rc = X86EMUL_CONTINUE;
 
         switch (c->ad_bytes) {
         case 2:
@@ -916,14 +924,18 @@ int
 x86_decode_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
 {
         struct decode_cache *c = &ctxt->decode;
-        int rc = 0;
+        int rc = X86EMUL_CONTINUE;
         int mode = ctxt->mode;
         int def_op_bytes, def_ad_bytes, group;
 
-        /* Shadow copy of register state. Committed on successful emulation. */
 
+        /* we cannot decode insn before we complete previous rep insn */
+        WARN_ON(ctxt->restart);
+
+        /* Shadow copy of register state. Committed on successful emulation. */
         memset(c, 0, sizeof(struct decode_cache));
-        c->eip = c->eip_orig = kvm_rip_read(ctxt->vcpu);
+        c->eip = ctxt->eip;
+        c->fetch.start = c->fetch.end = c->eip;
         ctxt->cs_base = seg_base(ctxt, VCPU_SREG_CS);
         memcpy(c->regs, ctxt->vcpu->arch.regs, sizeof c->regs);
 
@@ -1015,11 +1027,6 @@ done_prefixes:
                 }
         }
 
-        if (mode == X86EMUL_MODE_PROT64 && (c->d & No64)) {
-                kvm_report_emulation_failure(ctxt->vcpu, "invalid x86/64 instruction");
-                return -1;
-        }
-
         if (c->d & Group) {
                 group = c->d & GroupMask;
                 c->modrm = insn_fetch(u8, 1, c->eip);
@@ -1046,7 +1053,7 @@ done_prefixes:
                 rc = decode_modrm(ctxt, ops);
         else if (c->d & MemAbs)
                 rc = decode_abs(ctxt, ops);
-        if (rc)
+        if (rc != X86EMUL_CONTINUE)
                 goto done;
 
         if (!c->has_seg_override)
@@ -1057,6 +1064,10 @@ done_prefixes:
 
         if (c->ad_bytes != 8)
                 c->modrm_ea = (u32)c->modrm_ea;
+
+        if (c->rip_relative)
+                c->modrm_ea += c->eip;
+
         /*
          * Decode and fetch the source operand: register, memory
          * or immediate.
@@ -1091,6 +1102,8 @@ done_prefixes:
                         break;
                 }
                 c->src.type = OP_MEM;
+                c->src.ptr = (unsigned long *)c->modrm_ea;
+                c->src.val = 0;
                 break;
         case SrcImm:
         case SrcImmU:
@@ -1139,6 +1152,14 @@ done_prefixes:
                 c->src.bytes = 1;
                 c->src.val = 1;
                 break;
+        case SrcSI:
+                c->src.type = OP_MEM;
+                c->src.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
+                c->src.ptr = (unsigned long *)
+                        register_address(c,  seg_override_base(ctxt, c),
+                                         c->regs[VCPU_REGS_RSI]);
+                c->src.val = 0;
+                break;
         }
 
         /*
@@ -1168,6 +1189,12 @@ done_prefixes:
                 c->src2.bytes = 1;
                 c->src2.val = 1;
                 break;
+        case Src2Mem16:
+                c->src2.type = OP_MEM;
+                c->src2.bytes = 2;
+                c->src2.ptr = (unsigned long *)(c->modrm_ea + c->src.bytes);
+                c->src2.val = 0;
+                break;
         }
 
         /* Decode and fetch the destination operand: register or memory. */
@@ -1180,6 +1207,7 @@ done_prefixes:
                          c->twobyte && (c->b == 0xb6 || c->b == 0xb7));
                 break;
         case DstMem:
+        case DstMem64:
                 if ((c->d & ModRM) && c->modrm_mod == 3) {
                         c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
                         c->dst.type = OP_REG;
@@ -1188,12 +1216,24 @@ done_prefixes:
                         break;
                 }
                 c->dst.type = OP_MEM;
+                c->dst.ptr = (unsigned long *)c->modrm_ea;
+                if ((c->d & DstMask) == DstMem64)
+                        c->dst.bytes = 8;
+                else
+                        c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
+                c->dst.val = 0;
+                if (c->d & BitOp) {
+                        unsigned long mask = ~(c->dst.bytes * 8 - 1);
+
+                        c->dst.ptr = (void *)c->dst.ptr +
+                                                   (c->src.val & mask) / 8;
+                }
                 break;
         case DstAcc:
                 c->dst.type = OP_REG;
-                c->dst.bytes = c->op_bytes;
+                c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
                 c->dst.ptr = &c->regs[VCPU_REGS_RAX];
-                switch (c->op_bytes) {
+                switch (c->dst.bytes) {
                         case 1:
                                 c->dst.val = *(u8 *)c->dst.ptr;
                                 break;
@@ -1203,18 +1243,248 @@ done_prefixes:
                         case 4:
                                 c->dst.val = *(u32 *)c->dst.ptr;
                                 break;
+                        case 8:
+                                c->dst.val = *(u64 *)c->dst.ptr;
+                                break;
                 }
                 c->dst.orig_val = c->dst.val;
                 break;
+        case DstDI:
+                c->dst.type = OP_MEM;
+                c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
+                c->dst.ptr = (unsigned long *)
+                        register_address(c, es_base(ctxt),
+                                         c->regs[VCPU_REGS_RDI]);
+                c->dst.val = 0;
+                break;
         }
 
-        if (c->rip_relative)
-                c->modrm_ea += c->eip;
-
 done:
         return (rc == X86EMUL_UNHANDLEABLE) ? -1 : 0;
 }
 
+static int pio_in_emulated(struct x86_emulate_ctxt *ctxt,
+                           struct x86_emulate_ops *ops,
+                           unsigned int size, unsigned short port,
+                           void *dest)
+{
+        struct read_cache *rc = &ctxt->decode.io_read;
+
+        if (rc->pos == rc->end) { /* refill pio read ahead */
+                struct decode_cache *c = &ctxt->decode;
+                unsigned int in_page, n;
+                unsigned int count = c->rep_prefix ?
+                        address_mask(c, c->regs[VCPU_REGS_RCX]) : 1;
+                in_page = (ctxt->eflags & EFLG_DF) ?
+                        offset_in_page(c->regs[VCPU_REGS_RDI]) :
+                        PAGE_SIZE - offset_in_page(c->regs[VCPU_REGS_RDI]);
+                n = min(min(in_page, (unsigned int)sizeof(rc->data)) / size,
+                        count);
+                if (n == 0)
+                        n = 1;
+                rc->pos = rc->end = 0;
+                if (!ops->pio_in_emulated(size, port, rc->data, n, ctxt->vcpu))
+                        return 0;
+                rc->end = n * size;
+        }
+
+        memcpy(dest, rc->data + rc->pos, size);
+        rc->pos += size;
+        return 1;
+}
+
+static u32 desc_limit_scaled(struct desc_struct *desc)
+{
+        u32 limit = get_desc_limit(desc);
+
+        return desc->g ? (limit << 12) | 0xfff : limit;
+}
+
+static void get_descriptor_table_ptr(struct x86_emulate_ctxt *ctxt,
+                                     struct x86_emulate_ops *ops,
+                                     u16 selector, struct desc_ptr *dt)
+{
+        if (selector & 1 << 2) {
+                struct desc_struct desc;
+                memset (dt, 0, sizeof *dt);
+                if (!ops->get_cached_descriptor(&desc, VCPU_SREG_LDTR, ctxt->vcpu))
+                        return;
+
+                dt->size = desc_limit_scaled(&desc); /* what if limit > 65535? */
+                dt->address = get_desc_base(&desc);
+        } else
+                ops->get_gdt(dt, ctxt->vcpu);
+}
+
+/* allowed just for 8 bytes segments */
+static int read_segment_descriptor(struct x86_emulate_ctxt *ctxt,
+                                   struct x86_emulate_ops *ops,
+                                   u16 selector, struct desc_struct *desc)
+{
+        struct desc_ptr dt;
+        u16 index = selector >> 3;
+        int ret;
+        u32 err;
+        ulong addr;
+
+        get_descriptor_table_ptr(ctxt, ops, selector, &dt);
+
+        if (dt.size < index * 8 + 7) {
+                kvm_inject_gp(ctxt->vcpu, selector & 0xfffc);
+                return X86EMUL_PROPAGATE_FAULT;
+        }
+        addr = dt.address + index * 8;
+        ret = ops->read_std(addr, desc, sizeof *desc, ctxt->vcpu,  &err);
+        if (ret == X86EMUL_PROPAGATE_FAULT)
+                kvm_inject_page_fault(ctxt->vcpu, addr, err);
+
+       return ret;
+}
+
+/* allowed just for 8 bytes segments */
+static int write_segment_descriptor(struct x86_emulate_ctxt *ctxt,
+                                    struct x86_emulate_ops *ops,
+                                    u16 selector, struct desc_struct *desc)
+{
+        struct desc_ptr dt;
+        u16 index = selector >> 3;
+        u32 err;
+        ulong addr;
+        int ret;
+
+        get_descriptor_table_ptr(ctxt, ops, selector, &dt);
+
+        if (dt.size < index * 8 + 7) {
+                kvm_inject_gp(ctxt->vcpu, selector & 0xfffc);
+                return X86EMUL_PROPAGATE_FAULT;
+        }
+
+        addr = dt.address + index * 8;
+        ret = ops->write_std(addr, desc, sizeof *desc, ctxt->vcpu, &err);
+        if (ret == X86EMUL_PROPAGATE_FAULT)
+                kvm_inject_page_fault(ctxt->vcpu, addr, err);
+
+        return ret;
+}
+
+static int load_segment_descriptor(struct x86_emulate_ctxt *ctxt,
+                                   struct x86_emulate_ops *ops,
+                                   u16 selector, int seg)
+{
+        struct desc_struct seg_desc;
+        u8 dpl, rpl, cpl;
+        unsigned err_vec = GP_VECTOR;
+        u32 err_code = 0;
+        bool null_selector = !(selector & ~0x3); /* 0000-0003 are null */
+        int ret;
+
+        memset(&seg_desc, 0, sizeof seg_desc);
+
+        if ((seg <= VCPU_SREG_GS && ctxt->mode == X86EMUL_MODE_VM86)
+            || ctxt->mode == X86EMUL_MODE_REAL) {
+                /* set real mode segment descriptor */
+                set_desc_base(&seg_desc, selector << 4);
+                set_desc_limit(&seg_desc, 0xffff);
+                seg_desc.type = 3;
+                seg_desc.p = 1;
+                seg_desc.s = 1;
+                goto load;
+        }
+
+        /* NULL selector is not valid for TR, CS and SS */
+        if ((seg == VCPU_SREG_CS || seg == VCPU_SREG_SS || seg == VCPU_SREG_TR)
+            && null_selector)
+                goto exception;
+
+        /* TR should be in GDT only */
+        if (seg == VCPU_SREG_TR && (selector & (1 << 2)))
+                goto exception;
+
+        if (null_selector) /* for NULL selector skip all following checks */
+                goto load;
+
+        ret = read_segment_descriptor(ctxt, ops, selector, &seg_desc);
+        if (ret != X86EMUL_CONTINUE)
+                return ret;
+
+        err_code = selector & 0xfffc;
+        err_vec = GP_VECTOR;
+
+        /* can't load system descriptor into segment selecor */
+        if (seg <= VCPU_SREG_GS && !seg_desc.s)
+                goto exception;
+
+        if (!seg_desc.p) {
+                err_vec = (seg == VCPU_SREG_SS) ? SS_VECTOR : NP_VECTOR;
+                goto exception;
+        }
+
+        rpl = selector & 3;
+        dpl = seg_desc.dpl;
+        cpl = ops->cpl(ctxt->vcpu);
+
+        switch (seg) {
+        case VCPU_SREG_SS:
+                /*
+                 * segment is not a writable data segment or segment
+                 * selector's RPL != CPL or segment selector's RPL != CPL
+                 */
+                if (rpl != cpl || (seg_desc.type & 0xa) != 0x2 || dpl != cpl)
+                        goto exception;
+                break;
+        case VCPU_SREG_CS:
+                if (!(seg_desc.type & 8))
+                        goto exception;
+
+                if (seg_desc.type & 4) {
+                        /* conforming */
+                        if (dpl > cpl)
+                                goto exception;
+                } else {
+                        /* nonconforming */
+                        if (rpl > cpl || dpl != cpl)
+                                goto exception;
+                }
+                /* CS(RPL) <- CPL */
+                selector = (selector & 0xfffc) | cpl;
+                break;
+        case VCPU_SREG_TR:
+                if (seg_desc.s || (seg_desc.type != 1 && seg_desc.type != 9))
+                        goto exception;
+                break;
+        case VCPU_SREG_LDTR:
+                if (seg_desc.s || seg_desc.type != 2)
+                        goto exception;
+                break;
+        default: /*  DS, ES, FS, or GS */
+                /*
+                 * segment is not a data or readable code segment or
+                 * ((segment is a data or nonconforming code segment)
+                 * and (both RPL and CPL > DPL))
+                 */
+                if ((seg_desc.type & 0xa) == 0x8 ||
+                    (((seg_desc.type & 0xc) != 0xc) &&
+                     (rpl > dpl && cpl > dpl)))
+                        goto exception;
+                break;
+        }
+
+        if (seg_desc.s) {
+                /* mark segment as accessed */
+                seg_desc.type |= 1;
+                ret = write_segment_descriptor(ctxt, ops, selector, &seg_desc);
+                if (ret != X86EMUL_CONTINUE)
+                        return ret;
+        }
+load:
+        ops->set_segment_selector(selector, seg, ctxt->vcpu);
+        ops->set_cached_descriptor(&seg_desc, seg, ctxt->vcpu);
+        return X86EMUL_CONTINUE;
+exception:
+        kvm_queue_exception_e(ctxt->vcpu, err_vec, err_code);
+        return X86EMUL_PROPAGATE_FAULT;
+}
+
 static inline void emulate_push(struct x86_emulate_ctxt *ctxt)
 {
         struct decode_cache *c = &ctxt->decode;
@@ -1251,7 +1521,7 @@ static int emulate_popf(struct x86_emulate_ctxt *ctxt,
         int rc;
         unsigned long val, change_mask;
         int iopl = (ctxt->eflags & X86_EFLAGS_IOPL) >> IOPL_SHIFT;
-        int cpl = kvm_x86_ops->get_cpl(ctxt->vcpu);
+        int cpl = ops->cpl(ctxt->vcpu);
 
         rc = emulate_pop(ctxt, ops, &val, len);
         if (rc != X86EMUL_CONTINUE)
@@ -1306,10 +1576,10 @@ static int emulate_pop_sreg(struct x86_emulate_ctxt *ctxt,
         int rc;
 
         rc = emulate_pop(ctxt, ops, &selector, c->op_bytes);
-        if (rc != 0)
+        if (rc != X86EMUL_CONTINUE)
                 return rc;
 
-        rc = kvm_load_segment_descriptor(ctxt->vcpu, (u16)selector, seg);
+        rc = load_segment_descriptor(ctxt, ops, (u16)selector, seg);
         return rc;
 }
 
@@ -1332,7 +1602,7 @@ static int emulate_popa(struct x86_emulate_ctxt *ctxt,
                         struct x86_emulate_ops *ops)
 {
         struct decode_cache *c = &ctxt->decode;
-        int rc = 0;
+        int rc = X86EMUL_CONTINUE;
         int reg = VCPU_REGS_RDI;
 
         while (reg >= VCPU_REGS_RAX) {
@@ -1343,7 +1613,7 @@ static int emulate_popa(struct x86_emulate_ctxt *ctxt,
                 }
 
                 rc = emulate_pop(ctxt, ops, &c->regs[reg], c->op_bytes);
-                if (rc != 0)
+                if (rc != X86EMUL_CONTINUE)
                         break;
                 --reg;
         }
@@ -1354,12 +1624,8 @@ static inline int emulate_grp1a(struct x86_emulate_ctxt *ctxt,
                                 struct x86_emulate_ops *ops)
 {
         struct decode_cache *c = &ctxt->decode;
-        int rc;
 
-        rc = emulate_pop(ctxt, ops, &c->dst.val, c->dst.bytes);
-        if (rc != 0)
-                return rc;
-        return 0;
+        return emulate_pop(ctxt, ops, &c->dst.val, c->dst.bytes);
 }
 
 static inline void emulate_grp2(struct x86_emulate_ctxt *ctxt)
@@ -1395,7 +1661,6 @@ static inline int emulate_grp3(struct x86_emulate_ctxt *ctxt,
                                struct x86_emulate_ops *ops)
 {
         struct decode_cache *c = &ctxt->decode;
-        int rc = 0;
 
         switch (c->modrm_reg) {
         case 0 ... 1:   /* test */
@@ -1408,11 +1673,9 @@ static inline int emulate_grp3(struct x86_emulate_ctxt *ctxt,
                 emulate_1op("neg", c->dst, ctxt->eflags);
                 break;
         default:
-                DPRINTF("Cannot emulate %02x\n", c->b);
-                rc = X86EMUL_UNHANDLEABLE;
-                break;
+                return 0;
         }
-        return rc;
+        return 1;
 }
 
 static inline int emulate_grp45(struct x86_emulate_ctxt *ctxt,
@@ -1442,20 +1705,14 @@ static inline int emulate_grp45(struct x86_emulate_ctxt *ctxt,
                 emulate_push(ctxt);
                 break;
         }
-        return 0;
+        return X86EMUL_CONTINUE;
 }
 
 static inline int emulate_grp9(struct x86_emulate_ctxt *ctxt,
-                               struct x86_emulate_ops *ops,
-                               unsigned long memop)
+                               struct x86_emulate_ops *ops)
 {
         struct decode_cache *c = &ctxt->decode;
-        u64 old, new;
-        int rc;
-
-        rc = ops->read_emulated(memop, &old, 8, ctxt->vcpu);
-        if (rc != X86EMUL_CONTINUE)
-                return rc;
+        u64 old = c->dst.orig_val;
 
         if (((u32) (old >> 0) != (u32) c->regs[VCPU_REGS_RAX]) ||
             ((u32) (old >> 32) != (u32) c->regs[VCPU_REGS_RDX])) {
@@ -1463,17 +1720,13 @@ static inline int emulate_grp9(struct x86_emulate_ctxt *ctxt,
                 c->regs[VCPU_REGS_RAX] = (u32) (old >> 0);
                 c->regs[VCPU_REGS_RDX] = (u32) (old >> 32);
                 ctxt->eflags &= ~EFLG_ZF;
-
         } else {
-                new = ((u64)c->regs[VCPU_REGS_RCX] << 32) |
+                c->dst.val = ((u64)c->regs[VCPU_REGS_RCX] << 32) |
                        (u32) c->regs[VCPU_REGS_RBX];
 
-                rc = ops->cmpxchg_emulated(memop, &old, &new, 8, ctxt->vcpu);
-                if (rc != X86EMUL_CONTINUE)
-                        return rc;
                 ctxt->eflags |= EFLG_ZF;
         }
-        return 0;
+        return X86EMUL_CONTINUE;
 }
 
 static int emulate_ret_far(struct x86_emulate_ctxt *ctxt,
@@ -1484,14 +1737,14 @@ static int emulate_ret_far(struct x86_emulate_ctxt *ctxt,
         unsigned long cs;
 
         rc = emulate_pop(ctxt, ops, &c->eip, c->op_bytes);
-        if (rc)
+        if (rc != X86EMUL_CONTINUE)
                 return rc;
         if (c->op_bytes == 4)
                 c->eip = (u32)c->eip;
         rc = emulate_pop(ctxt, ops, &cs, c->op_bytes);
-        if (rc)
+        if (rc != X86EMUL_CONTINUE)
                 return rc;
-        rc = kvm_load_segment_descriptor(ctxt->vcpu, (u16)cs, VCPU_SREG_CS);
+        rc = load_segment_descriptor(ctxt, ops, (u16)cs, VCPU_SREG_CS);
         return rc;
 }
 
@@ -1544,7 +1797,7 @@ static inline int writeback(struct x86_emulate_ctxt *ctxt,
         default:
                 break;
         }
-        return 0;
+        return X86EMUL_CONTINUE;
 }
 
 static void toggle_interruptibility(struct x86_emulate_ctxt *ctxt, u32 mask)
@@ -1598,8 +1851,11 @@ emulate_syscall(struct x86_emulate_ctxt *ctxt)
         u64 msr_data;
 
         /* syscall is not available in real mode */
-        if (ctxt->mode == X86EMUL_MODE_REAL || ctxt->mode == X86EMUL_MODE_VM86)
-                return X86EMUL_UNHANDLEABLE;
+        if (ctxt->mode == X86EMUL_MODE_REAL ||
+            ctxt->mode == X86EMUL_MODE_VM86) {
+                kvm_queue_exception(ctxt->vcpu, UD_VECTOR);
+                return X86EMUL_PROPAGATE_FAULT;
+        }
 
         setup_syscalls_segments(ctxt, &cs, &ss);
 
@@ -1649,14 +1905,16 @@ emulate_sysenter(struct x86_emulate_ctxt *ctxt)
         /* inject #GP if in real mode */
         if (ctxt->mode == X86EMUL_MODE_REAL) {
                 kvm_inject_gp(ctxt->vcpu, 0);
-                return X86EMUL_UNHANDLEABLE;
+                return X86EMUL_PROPAGATE_FAULT;
         }
 
         /* XXX sysenter/sysexit have not been tested in 64bit mode.
         * Therefore, we inject an #UD.
         */
-        if (ctxt->mode == X86EMUL_MODE_PROT64)
-                return X86EMUL_UNHANDLEABLE;
+        if (ctxt->mode == X86EMUL_MODE_PROT64) {
+                kvm_queue_exception(ctxt->vcpu, UD_VECTOR);
+                return X86EMUL_PROPAGATE_FAULT;
+        }
 
         setup_syscalls_segments(ctxt, &cs, &ss);
 
@@ -1711,7 +1969,7 @@ emulate_sysexit(struct x86_emulate_ctxt *ctxt)
         if (ctxt->mode == X86EMUL_MODE_REAL ||
             ctxt->mode == X86EMUL_MODE_VM86) {
                 kvm_inject_gp(ctxt->vcpu, 0);
-                return X86EMUL_UNHANDLEABLE;
+                return X86EMUL_PROPAGATE_FAULT;
         }
 
         setup_syscalls_segments(ctxt, &cs, &ss);
@@ -1756,7 +2014,8 @@ emulate_sysexit(struct x86_emulate_ctxt *ctxt)
         return X86EMUL_CONTINUE;
 }
 
-static bool emulator_bad_iopl(struct x86_emulate_ctxt *ctxt)
+static bool emulator_bad_iopl(struct x86_emulate_ctxt *ctxt,
+                              struct x86_emulate_ops *ops)
 {
         int iopl;
         if (ctxt->mode == X86EMUL_MODE_REAL)
@@ -1764,7 +2023,7 @@ static bool emulator_bad_iopl(struct x86_emulate_ctxt *ctxt)
         if (ctxt->mode == X86EMUL_MODE_VM86)
                 return true;
         iopl = (ctxt->eflags & X86_EFLAGS_IOPL) >> IOPL_SHIFT;
-        return kvm_x86_ops->get_cpl(ctxt->vcpu) > iopl;
+        return ops->cpl(ctxt->vcpu) > iopl;
 }
 
 static bool emulator_io_port_access_allowed(struct x86_emulate_ctxt *ctxt,
@@ -1801,22 +2060,419 @@ static bool emulator_io_permited(struct x86_emulate_ctxt *ctxt,
                                  struct x86_emulate_ops *ops,
                                  u16 port, u16 len)
 {
-        if (emulator_bad_iopl(ctxt))
+        if (emulator_bad_iopl(ctxt, ops))
                 if (!emulator_io_port_access_allowed(ctxt, ops, port, len))
                         return false;
         return true;
 }
 
+static u32 get_cached_descriptor_base(struct x86_emulate_ctxt *ctxt,
+                                      struct x86_emulate_ops *ops,
+                                      int seg)
+{
+        struct desc_struct desc;
+        if (ops->get_cached_descriptor(&desc, seg, ctxt->vcpu))
+                return get_desc_base(&desc);
+        else
+                return ~0;
+}
+
+static void save_state_to_tss16(struct x86_emulate_ctxt *ctxt,
+                                struct x86_emulate_ops *ops,
+                                struct tss_segment_16 *tss)
+{
+        struct decode_cache *c = &ctxt->decode;
+
+        tss->ip = c->eip;
+        tss->flag = ctxt->eflags;
+        tss->ax = c->regs[VCPU_REGS_RAX];
+        tss->cx = c->regs[VCPU_REGS_RCX];
+        tss->dx = c->regs[VCPU_REGS_RDX];
+        tss->bx = c->regs[VCPU_REGS_RBX];
+        tss->sp = c->regs[VCPU_REGS_RSP];
+        tss->bp = c->regs[VCPU_REGS_RBP];
+        tss->si = c->regs[VCPU_REGS_RSI];
+        tss->di = c->regs[VCPU_REGS_RDI];
+
+        tss->es = ops->get_segment_selector(VCPU_SREG_ES, ctxt->vcpu);
+        tss->cs = ops->get_segment_selector(VCPU_SREG_CS, ctxt->vcpu);
+        tss->ss = ops->get_segment_selector(VCPU_SREG_SS, ctxt->vcpu);
+        tss->ds = ops->get_segment_selector(VCPU_SREG_DS, ctxt->vcpu);
+        tss->ldt = ops->get_segment_selector(VCPU_SREG_LDTR, ctxt->vcpu);
+}
+
+static int load_state_from_tss16(struct x86_emulate_ctxt *ctxt,
+                                 struct x86_emulate_ops *ops,
+                                 struct tss_segment_16 *tss)
+{
+        struct decode_cache *c = &ctxt->decode;
+        int ret;
+
+        c->eip = tss->ip;
+        ctxt->eflags = tss->flag | 2;
+        c->regs[VCPU_REGS_RAX] = tss->ax;
+        c->regs[VCPU_REGS_RCX] = tss->cx;
+        c->regs[VCPU_REGS_RDX] = tss->dx;
+        c->regs[VCPU_REGS_RBX] = tss->bx;
+        c->regs[VCPU_REGS_RSP] = tss->sp;
+        c->regs[VCPU_REGS_RBP] = tss->bp;
+        c->regs[VCPU_REGS_RSI] = tss->si;
+        c->regs[VCPU_REGS_RDI] = tss->di;
+
+        /*
+         * SDM says that segment selectors are loaded before segment
+         * descriptors
+         */
+        ops->set_segment_selector(tss->ldt, VCPU_SREG_LDTR, ctxt->vcpu);
+        ops->set_segment_selector(tss->es, VCPU_SREG_ES, ctxt->vcpu);
+        ops->set_segment_selector(tss->cs, VCPU_SREG_CS, ctxt->vcpu);
+        ops->set_segment_selector(tss->ss, VCPU_SREG_SS, ctxt->vcpu);
+        ops->set_segment_selector(tss->ds, VCPU_SREG_DS, ctxt->vcpu);
+
+        /*
+         * Now load segment descriptors. If fault happenes at this stage
+         * it is handled in a context of new task
+         */
+        ret = load_segment_descriptor(ctxt, ops, tss->ldt, VCPU_SREG_LDTR);
+        if (ret != X86EMUL_CONTINUE)
+                return ret;
+        ret = load_segment_descriptor(ctxt, ops, tss->es, VCPU_SREG_ES);
+        if (ret != X86EMUL_CONTINUE)
+                return ret;
+        ret = load_segment_descriptor(ctxt, ops, tss->cs, VCPU_SREG_CS);
+        if (ret != X86EMUL_CONTINUE)
+                return ret;
+        ret = load_segment_descriptor(ctxt, ops, tss->ss, VCPU_SREG_SS);
+        if (ret != X86EMUL_CONTINUE)
+                return ret;
+        ret = load_segment_descriptor(ctxt, ops, tss->ds, VCPU_SREG_DS);
+        if (ret != X86EMUL_CONTINUE)
+                return ret;
+
+        return X86EMUL_CONTINUE;
+}
+
+static int task_switch_16(struct x86_emulate_ctxt *ctxt,
+                          struct x86_emulate_ops *ops,
+                          u16 tss_selector, u16 old_tss_sel,
+                          ulong old_tss_base, struct desc_struct *new_desc)
+{
+        struct tss_segment_16 tss_seg;
+        int ret;
+        u32 err, new_tss_base = get_desc_base(new_desc);
+
+        ret = ops->read_std(old_tss_base, &tss_seg, sizeof tss_seg, ctxt->vcpu,
+                            &err);
+        if (ret == X86EMUL_PROPAGATE_FAULT) {
+                /* FIXME: need to provide precise fault address */
+                kvm_inject_page_fault(ctxt->vcpu, old_tss_base, err);
+                return ret;
+        }
+
+        save_state_to_tss16(ctxt, ops, &tss_seg);
+
+        ret = ops->write_std(old_tss_base, &tss_seg, sizeof tss_seg, ctxt->vcpu,
+                             &err);
+        if (ret == X86EMUL_PROPAGATE_FAULT) {
+                /* FIXME: need to provide precise fault address */
+                kvm_inject_page_fault(ctxt->vcpu, old_tss_base, err);
+                return ret;
+        }
+
+        ret = ops->read_std(new_tss_base, &tss_seg, sizeof tss_seg, ctxt->vcpu,
+                            &err);
+        if (ret == X86EMUL_PROPAGATE_FAULT) {
+                /* FIXME: need to provide precise fault address */
+                kvm_inject_page_fault(ctxt->vcpu, new_tss_base, err);
+                return ret;
+        }
+
+        if (old_tss_sel != 0xffff) {
+                tss_seg.prev_task_link = old_tss_sel;
+
+                ret = ops->write_std(new_tss_base,
+                                     &tss_seg.prev_task_link,
+                                     sizeof tss_seg.prev_task_link,
+                                     ctxt->vcpu, &err);
+                if (ret == X86EMUL_PROPAGATE_FAULT) {
+                        /* FIXME: need to provide precise fault address */
+                        kvm_inject_page_fault(ctxt->vcpu, new_tss_base, err);
+                        return ret;
+                }
+        }
+
+        return load_state_from_tss16(ctxt, ops, &tss_seg);
+}
+
+static void save_state_to_tss32(struct x86_emulate_ctxt *ctxt,
+                                struct x86_emulate_ops *ops,
+                                struct tss_segment_32 *tss)
+{
+        struct decode_cache *c = &ctxt->decode;
+
+        tss->cr3 = ops->get_cr(3, ctxt->vcpu);
+        tss->eip = c->eip;
+        tss->eflags = ctxt->eflags;
+        tss->eax = c->regs[VCPU_REGS_RAX];
+        tss->ecx = c->regs[VCPU_REGS_RCX];
+        tss->edx = c->regs[VCPU_REGS_RDX];
+        tss->ebx = c->regs[VCPU_REGS_RBX];
+        tss->esp = c->regs[VCPU_REGS_RSP];
+        tss->ebp = c->regs[VCPU_REGS_RBP];
+        tss->esi = c->regs[VCPU_REGS_RSI];
+        tss->edi = c->regs[VCPU_REGS_RDI];
+
+        tss->es = ops->get_segment_selector(VCPU_SREG_ES, ctxt->vcpu);
+        tss->cs = ops->get_segment_selector(VCPU_SREG_CS, ctxt->vcpu);
+        tss->ss = ops->get_segment_selector(VCPU_SREG_SS, ctxt->vcpu);
+        tss->ds = ops->get_segment_selector(VCPU_SREG_DS, ctxt->vcpu);
+        tss->fs = ops->get_segment_selector(VCPU_SREG_FS, ctxt->vcpu);
+        tss->gs = ops->get_segment_selector(VCPU_SREG_GS, ctxt->vcpu);
+        tss->ldt_selector = ops->get_segment_selector(VCPU_SREG_LDTR, ctxt->vcpu);
+}
+
+static int load_state_from_tss32(struct x86_emulate_ctxt *ctxt,
+                                 struct x86_emulate_ops *ops,
+                                 struct tss_segment_32 *tss)
+{
+        struct decode_cache *c = &ctxt->decode;
+        int ret;
+
+        ops->set_cr(3, tss->cr3, ctxt->vcpu);
+        c->eip = tss->eip;
+        ctxt->eflags = tss->eflags | 2;
+        c->regs[VCPU_REGS_RAX] = tss->eax;
+        c->regs[VCPU_REGS_RCX] = tss->ecx;
+        c->regs[VCPU_REGS_RDX] = tss->edx;
+        c->regs[VCPU_REGS_RBX] = tss->ebx;
+        c->regs[VCPU_REGS_RSP] = tss->esp;
+        c->regs[VCPU_REGS_RBP] = tss->ebp;
+        c->regs[VCPU_REGS_RSI] = tss->esi;
+        c->regs[VCPU_REGS_RDI] = tss->edi;
+
+        /*
+         * SDM says that segment selectors are loaded before segment
+         * descriptors
+         */
+        ops->set_segment_selector(tss->ldt_selector, VCPU_SREG_LDTR, ctxt->vcpu);
+        ops->set_segment_selector(tss->es, VCPU_SREG_ES, ctxt->vcpu);
+        ops->set_segment_selector(tss->cs, VCPU_SREG_CS, ctxt->vcpu);
+        ops->set_segment_selector(tss->ss, VCPU_SREG_SS, ctxt->vcpu);
+        ops->set_segment_selector(tss->ds, VCPU_SREG_DS, ctxt->vcpu);
+        ops->set_segment_selector(tss->fs, VCPU_SREG_FS, ctxt->vcpu);
+        ops->set_segment_selector(tss->gs, VCPU_SREG_GS, ctxt->vcpu);
+
+        /*
+         * Now load segment descriptors. If fault happenes at this stage
+         * it is handled in a context of new task
+         */
+        ret = load_segment_descriptor(ctxt, ops, tss->ldt_selector, VCPU_SREG_LDTR);
+        if (ret != X86EMUL_CONTINUE)
+                return ret;
+        ret = load_segment_descriptor(ctxt, ops, tss->es, VCPU_SREG_ES);
+        if (ret != X86EMUL_CONTINUE)
+                return ret;
+        ret = load_segment_descriptor(ctxt, ops, tss->cs, VCPU_SREG_CS);
+        if (ret != X86EMUL_CONTINUE)
+                return ret;
+        ret = load_segment_descriptor(ctxt, ops, tss->ss, VCPU_SREG_SS);
+        if (ret != X86EMUL_CONTINUE)
+                return ret;
+        ret = load_segment_descriptor(ctxt, ops, tss->ds, VCPU_SREG_DS);
+        if (ret != X86EMUL_CONTINUE)
+                return ret;
+        ret = load_segment_descriptor(ctxt, ops, tss->fs, VCPU_SREG_FS);
+        if (ret != X86EMUL_CONTINUE)
+                return ret;
+        ret = load_segment_descriptor(ctxt, ops, tss->gs, VCPU_SREG_GS);
+        if (ret != X86EMUL_CONTINUE)
+                return ret;
+
+        return X86EMUL_CONTINUE;
+}
+
+static int task_switch_32(struct x86_emulate_ctxt *ctxt,
+                          struct x86_emulate_ops *ops,
+                          u16 tss_selector, u16 old_tss_sel,
+                          ulong old_tss_base, struct desc_struct *new_desc)
+{
+        struct tss_segment_32 tss_seg;
+        int ret;
+        u32 err, new_tss_base = get_desc_base(new_desc);
+
+        ret = ops->read_std(old_tss_base, &tss_seg, sizeof tss_seg, ctxt->vcpu,
+                            &err);
+        if (ret == X86EMUL_PROPAGATE_FAULT) {
+                /* FIXME: need to provide precise fault address */
+                kvm_inject_page_fault(ctxt->vcpu, old_tss_base, err);
+                return ret;
+        }
+
+        save_state_to_tss32(ctxt, ops, &tss_seg);
+
+        ret = ops->write_std(old_tss_base, &tss_seg, sizeof tss_seg, ctxt->vcpu,
+                             &err);
+        if (ret == X86EMUL_PROPAGATE_FAULT) {
+                /* FIXME: need to provide precise fault address */
+                kvm_inject_page_fault(ctxt->vcpu, old_tss_base, err);
+                return ret;
+        }
+
+        ret = ops->read_std(new_tss_base, &tss_seg, sizeof tss_seg, ctxt->vcpu,
+                            &err);
+        if (ret == X86EMUL_PROPAGATE_FAULT) {
+                /* FIXME: need to provide precise fault address */
+                kvm_inject_page_fault(ctxt->vcpu, new_tss_base, err);
+                return ret;
+        }
+
+        if (old_tss_sel != 0xffff) {
+                tss_seg.prev_task_link = old_tss_sel;
+
+                ret = ops->write_std(new_tss_base,
+                                     &tss_seg.prev_task_link,
+                                     sizeof tss_seg.prev_task_link,
+                                     ctxt->vcpu, &err);
+                if (ret == X86EMUL_PROPAGATE_FAULT) {
+                        /* FIXME: need to provide precise fault address */
+                        kvm_inject_page_fault(ctxt->vcpu, new_tss_base, err);
+                        return ret;
+                }
+        }
+
+        return load_state_from_tss32(ctxt, ops, &tss_seg);
+}
+
+static int emulator_do_task_switch(struct x86_emulate_ctxt *ctxt,
+                                   struct x86_emulate_ops *ops,
+                                   u16 tss_selector, int reason,
+                                   bool has_error_code, u32 error_code)
+{
+        struct desc_struct curr_tss_desc, next_tss_desc;
+        int ret;
+        u16 old_tss_sel = ops->get_segment_selector(VCPU_SREG_TR, ctxt->vcpu);
+        ulong old_tss_base =
+                get_cached_descriptor_base(ctxt, ops, VCPU_SREG_TR);
+        u32 desc_limit;
+
+        /* FIXME: old_tss_base == ~0 ? */
+
+        ret = read_segment_descriptor(ctxt, ops, tss_selector, &next_tss_desc);
+        if (ret != X86EMUL_CONTINUE)
+                return ret;
+        ret = read_segment_descriptor(ctxt, ops, old_tss_sel, &curr_tss_desc);
+        if (ret != X86EMUL_CONTINUE)
+                return ret;
+
+        /* FIXME: check that next_tss_desc is tss */
+
+        if (reason != TASK_SWITCH_IRET) {
+                if ((tss_selector & 3) > next_tss_desc.dpl ||
+                    ops->cpl(ctxt->vcpu) > next_tss_desc.dpl) {
+                        kvm_inject_gp(ctxt->vcpu, 0);
+                        return X86EMUL_PROPAGATE_FAULT;
+                }
+        }
+
+        desc_limit = desc_limit_scaled(&next_tss_desc);
+        if (!next_tss_desc.p ||
+            ((desc_limit < 0x67 && (next_tss_desc.type & 8)) ||
+             desc_limit < 0x2b)) {
+                kvm_queue_exception_e(ctxt->vcpu, TS_VECTOR,
+                                      tss_selector & 0xfffc);
+                return X86EMUL_PROPAGATE_FAULT;
+        }
+
+        if (reason == TASK_SWITCH_IRET || reason == TASK_SWITCH_JMP) {
+                curr_tss_desc.type &= ~(1 << 1); /* clear busy flag */
+                write_segment_descriptor(ctxt, ops, old_tss_sel,
+                                         &curr_tss_desc);
+        }
+
+        if (reason == TASK_SWITCH_IRET)
+                ctxt->eflags = ctxt->eflags & ~X86_EFLAGS_NT;
+
+        /* set back link to prev task only if NT bit is set in eflags
+           note that old_tss_sel is not used afetr this point */
+        if (reason != TASK_SWITCH_CALL && reason != TASK_SWITCH_GATE)
+                old_tss_sel = 0xffff;
+
+        if (next_tss_desc.type & 8)
+                ret = task_switch_32(ctxt, ops, tss_selector, old_tss_sel,
+                                     old_tss_base, &next_tss_desc);
+        else
+                ret = task_switch_16(ctxt, ops, tss_selector, old_tss_sel,
+                                     old_tss_base, &next_tss_desc);
+        if (ret != X86EMUL_CONTINUE)
+                return ret;
+
+        if (reason == TASK_SWITCH_CALL || reason == TASK_SWITCH_GATE)
+                ctxt->eflags = ctxt->eflags | X86_EFLAGS_NT;
+
+        if (reason != TASK_SWITCH_IRET) {
+                next_tss_desc.type |= (1 << 1); /* set busy flag */
+                write_segment_descriptor(ctxt, ops, tss_selector,
+                                         &next_tss_desc);
+        }
+
+        ops->set_cr(0,  ops->get_cr(0, ctxt->vcpu) | X86_CR0_TS, ctxt->vcpu);
+        ops->set_cached_descriptor(&next_tss_desc, VCPU_SREG_TR, ctxt->vcpu);
+        ops->set_segment_selector(tss_selector, VCPU_SREG_TR, ctxt->vcpu);
+
+        if (has_error_code) {
+                struct decode_cache *c = &ctxt->decode;
+
+                c->op_bytes = c->ad_bytes = (next_tss_desc.type & 8) ? 4 : 2;
+                c->lock_prefix = 0;
+                c->src.val = (unsigned long) error_code;
+                emulate_push(ctxt);
+        }
+
+        return ret;
+}
+
+int emulator_task_switch(struct x86_emulate_ctxt *ctxt,
+                         struct x86_emulate_ops *ops,
+                         u16 tss_selector, int reason,
+                         bool has_error_code, u32 error_code)
+{
+        struct decode_cache *c = &ctxt->decode;
+        int rc;
+
+        memset(c, 0, sizeof(struct decode_cache));
+        c->eip = ctxt->eip;
+        memcpy(c->regs, ctxt->vcpu->arch.regs, sizeof c->regs);
+        c->dst.type = OP_NONE;
+
+        rc = emulator_do_task_switch(ctxt, ops, tss_selector, reason,
+                                     has_error_code, error_code);
+
+        if (rc == X86EMUL_CONTINUE) {
+                memcpy(ctxt->vcpu->arch.regs, c->regs, sizeof c->regs);
+                kvm_rip_write(ctxt->vcpu, c->eip);
+                rc = writeback(ctxt, ops);
+        }
+
+        return (rc == X86EMUL_UNHANDLEABLE) ? -1 : 0;
+}
+
+static void string_addr_inc(struct x86_emulate_ctxt *ctxt, unsigned long base,
+                            int reg, struct operand *op)
+{
+        struct decode_cache *c = &ctxt->decode;
+        int df = (ctxt->eflags & EFLG_DF) ? -1 : 1;
+
+        register_address_increment(c, &c->regs[reg], df * op->bytes);
+        op->ptr = (unsigned long *)register_address(c,  base, c->regs[reg]);
+}
+
 int
 x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
 {
-        unsigned long memop = 0;
         u64 msr_data;
-        unsigned long saved_eip = 0;
         struct decode_cache *c = &ctxt->decode;
-        unsigned int port;
-        int io_dir_in;
-        int rc = 0;
+        int rc = X86EMUL_CONTINUE;
+        int saved_dst_type = c->dst.type;
 
         ctxt->interruptibility = 0;
 
@@ -1826,26 +2482,30 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
          */
 
         memcpy(c->regs, ctxt->vcpu->arch.regs, sizeof c->regs);
-        saved_eip = c->eip;
+
+        if (ctxt->mode == X86EMUL_MODE_PROT64 && (c->d & No64)) {
+                kvm_queue_exception(ctxt->vcpu, UD_VECTOR);
+                goto done;
+        }
 
         /* LOCK prefix is allowed only with some instructions */
-        if (c->lock_prefix && !(c->d & Lock)) {
+        if (c->lock_prefix && (!(c->d & Lock) || c->dst.type != OP_MEM)) {
                 kvm_queue_exception(ctxt->vcpu, UD_VECTOR);
                 goto done;
         }
 
         /* Privileged instruction can be executed only in CPL=0 */
-        if ((c->d & Priv) && kvm_x86_ops->get_cpl(ctxt->vcpu)) {
+        if ((c->d & Priv) && ops->cpl(ctxt->vcpu)) {
                 kvm_inject_gp(ctxt->vcpu, 0);
                 goto done;
         }
 
-        if (((c->d & ModRM) && (c->modrm_mod != 3)) || (c->d & MemAbs))
-                memop = c->modrm_ea;
-
         if (c->rep_prefix && (c->d & String)) {
+                ctxt->restart = true;
                 /* All REP prefixes have the same first termination condition */
-                if (c->regs[VCPU_REGS_RCX] == 0) {
+                if (address_mask(c, c->regs[VCPU_REGS_RCX]) == 0) {
+                string_done:
+                        ctxt->restart = false;
                         kvm_rip_write(ctxt->vcpu, c->eip);
                         goto done;
                 }
@@ -1857,25 +2517,18 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
                  *      - if REPNE/REPNZ and ZF = 1 then done
                  */
                 if ((c->b == 0xa6) || (c->b == 0xa7) ||
-                                (c->b == 0xae) || (c->b == 0xaf)) {
+                    (c->b == 0xae) || (c->b == 0xaf)) {
                         if ((c->rep_prefix == REPE_PREFIX) &&
-                                ((ctxt->eflags & EFLG_ZF) == 0)) {
-                                        kvm_rip_write(ctxt->vcpu, c->eip);
-                                        goto done;
-                        }
+                            ((ctxt->eflags & EFLG_ZF) == 0))
+                                goto string_done;
                         if ((c->rep_prefix == REPNE_PREFIX) &&
-                                ((ctxt->eflags & EFLG_ZF) == EFLG_ZF)) {
-                                kvm_rip_write(ctxt->vcpu, c->eip);
-                                goto done;
-                        }
+                            ((ctxt->eflags & EFLG_ZF) == EFLG_ZF))
+                                goto string_done;
                 }
-                c->regs[VCPU_REGS_RCX]--;
-                c->eip = kvm_rip_read(ctxt->vcpu);
+                c->eip = ctxt->eip;
         }
 
         if (c->src.type == OP_MEM) {
-                c->src.ptr = (unsigned long *)memop;
-                c->src.val = 0;
                 rc = ops->read_emulated((unsigned long)c->src.ptr,
                                         &c->src.val,
                                         c->src.bytes,
@@ -1885,29 +2538,25 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
                 c->src.orig_val = c->src.val;
         }
 
+        if (c->src2.type == OP_MEM) {
+                rc = ops->read_emulated((unsigned long)c->src2.ptr,
+                                        &c->src2.val,
+                                        c->src2.bytes,
+                                        ctxt->vcpu);
+                if (rc != X86EMUL_CONTINUE)
+                        goto done;
+        }
+
         if ((c->d & DstMask) == ImplicitOps)
                 goto special_insn;
 
 
-        if (c->dst.type == OP_MEM) {
-                c->dst.ptr = (unsigned long *)memop;
-                c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
-                c->dst.val = 0;
-                if (c->d & BitOp) {
-                        unsigned long mask = ~(c->dst.bytes * 8 - 1);
-
-                        c->dst.ptr = (void *)c->dst.ptr +
-                                                   (c->src.val & mask) / 8;
-                }
-                if (!(c->d & Mov)) {
-                        /* optimisation - avoid slow emulated read */
-                        rc = ops->read_emulated((unsigned long)c->dst.ptr,
-                                                &c->dst.val,
-                                                c->dst.bytes,
-                                                ctxt->vcpu);
-                        if (rc != X86EMUL_CONTINUE)
-                                goto done;
-                }
+        if ((c->dst.type == OP_MEM) && !(c->d & Mov)) {
+                /* optimisation - avoid slow emulated read if Mov */
+                rc = ops->read_emulated((unsigned long)c->dst.ptr, &c->dst.val,
+                                        c->dst.bytes, ctxt->vcpu);
+                if (rc != X86EMUL_CONTINUE)
+                        goto done;
         }
         c->dst.orig_val = c->dst.val;
 
@@ -1926,7 +2575,7 @@ special_insn:
                 break;
         case 0x07:              /* pop es */
                 rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_ES);
-                if (rc != 0)
+                if (rc != X86EMUL_CONTINUE)
                         goto done;
                 break;
         case 0x08 ... 0x0d:
@@ -1945,7 +2594,7 @@ special_insn:
                 break;
         case 0x17:              /* pop ss */
                 rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_SS);
-                if (rc != 0)
+                if (rc != X86EMUL_CONTINUE)
                         goto done;
                 break;
         case 0x18 ... 0x1d:
@@ -1957,7 +2606,7 @@ special_insn:
                 break;
         case 0x1f:              /* pop ds */
                 rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_DS);
-                if (rc != 0)
+                if (rc != X86EMUL_CONTINUE)
                         goto done;
                 break;
         case 0x20 ... 0x25:
@@ -1988,7 +2637,7 @@ special_insn:
         case 0x58 ... 0x5f: /* pop reg */
         pop_instruction:
                 rc = emulate_pop(ctxt, ops, &c->dst.val, c->op_bytes);
-                if (rc != 0)
+                if (rc != X86EMUL_CONTINUE)
                         goto done;
                 break;
         case 0x60:      /* pusha */
@@ -1996,7 +2645,7 @@ special_insn:
                 break;
         case 0x61:      /* popa */
                 rc = emulate_popa(ctxt, ops);
-                if (rc != 0)
+                if (rc != X86EMUL_CONTINUE)
                         goto done;
                 break;
         case 0x63:              /* movsxd */
@@ -2010,47 +2659,29 @@ special_insn:
                 break;
         case 0x6c:              /* insb */
         case 0x6d:              /* insw/insd */
+                c->dst.bytes = min(c->dst.bytes, 4u);
                 if (!emulator_io_permited(ctxt, ops, c->regs[VCPU_REGS_RDX],
-                                          (c->d & ByteOp) ? 1 : c->op_bytes)) {
+                                          c->dst.bytes)) {
                         kvm_inject_gp(ctxt->vcpu, 0);
                         goto done;
                 }
-                if (kvm_emulate_pio_string(ctxt->vcpu,
-                                1,
-                                (c->d & ByteOp) ? 1 : c->op_bytes,
-                                c->rep_prefix ?
-                                address_mask(c, c->regs[VCPU_REGS_RCX]) : 1,
-                                (ctxt->eflags & EFLG_DF),
-                                register_address(c, es_base(ctxt),
-                                                 c->regs[VCPU_REGS_RDI]),
-                                c->rep_prefix,
-                                c->regs[VCPU_REGS_RDX]) == 0) {
-                        c->eip = saved_eip;
-                        return -1;
-                }
-                return 0;
+                if (!pio_in_emulated(ctxt, ops, c->dst.bytes,
+                                     c->regs[VCPU_REGS_RDX], &c->dst.val))
+                        goto done; /* IO is needed, skip writeback */
+                break;
         case 0x6e:              /* outsb */
         case 0x6f:              /* outsw/outsd */
+                c->src.bytes = min(c->src.bytes, 4u);
                 if (!emulator_io_permited(ctxt, ops, c->regs[VCPU_REGS_RDX],
-                                          (c->d & ByteOp) ? 1 : c->op_bytes)) {
+                                          c->src.bytes)) {
                         kvm_inject_gp(ctxt->vcpu, 0);
                         goto done;
                 }
-                if (kvm_emulate_pio_string(ctxt->vcpu,
-                                0,
-                                (c->d & ByteOp) ? 1 : c->op_bytes,
-                                c->rep_prefix ?
-                                address_mask(c, c->regs[VCPU_REGS_RCX]) : 1,
-                                (ctxt->eflags & EFLG_DF),
-                                         register_address(c,
-                                          seg_override_base(ctxt, c),
-                                                 c->regs[VCPU_REGS_RSI]),
-                                c->rep_prefix,
-                                c->regs[VCPU_REGS_RDX]) == 0) {
-                        c->eip = saved_eip;
-                        return -1;
-                }
-                return 0;
+                ops->pio_out_emulated(c->src.bytes, c->regs[VCPU_REGS_RDX],
+                                      &c->src.val, 1, ctxt->vcpu);
+
+                c->dst.type = OP_NONE; /* nothing to writeback */
+                break;
         case 0x70 ... 0x7f: /* jcc (short) */
                 if (test_cc(c->b, ctxt->eflags))
                         jmp_rel(c, c->src.val);
@@ -2107,12 +2738,11 @@ special_insn:
         case 0x8c: { /* mov r/m, sreg */
                 struct kvm_segment segreg;
 
-                if (c->modrm_reg <= 5)
+                if (c->modrm_reg <= VCPU_SREG_GS)
                         kvm_get_segment(ctxt->vcpu, &segreg, c->modrm_reg);
                 else {
-                        printk(KERN_INFO "0x8c: Invalid segreg in modrm byte 0x%02x\n",
-                               c->modrm);
-                        goto cannot_emulate;
+                        kvm_queue_exception(ctxt->vcpu, UD_VECTOR);
+                        goto done;
                 }
                 c->dst.val = segreg.selector;
                 break;
@@ -2132,16 +2762,16 @@ special_insn:
                 }
 
                 if (c->modrm_reg == VCPU_SREG_SS)
-                        toggle_interruptibility(ctxt, X86_SHADOW_INT_MOV_SS);
+                        toggle_interruptibility(ctxt, KVM_X86_SHADOW_INT_MOV_SS);
 
-                rc = kvm_load_segment_descriptor(ctxt->vcpu, sel, c->modrm_reg);
+                rc = load_segment_descriptor(ctxt, ops, sel, c->modrm_reg);
 
                 c->dst.type = OP_NONE;  /* Disable writeback. */
                 break;
         }
         case 0x8f:              /* pop (sole member of Grp1a) */
                 rc = emulate_grp1a(ctxt, ops);
-                if (rc != 0)
+                if (rc != X86EMUL_CONTINUE)
                         goto done;
                 break;
         case 0x90: /* nop / xchg r8,rax */
@@ -2175,89 +2805,16 @@ special_insn:
                 c->dst.val = (unsigned long)c->regs[VCPU_REGS_RAX];
                 break;
         case 0xa4 ... 0xa5:     /* movs */
-                c->dst.type = OP_MEM;
-                c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
-                c->dst.ptr = (unsigned long *)register_address(c,
-                                                   es_base(ctxt),
-                                                   c->regs[VCPU_REGS_RDI]);
-                rc = ops->read_emulated(register_address(c,
-                                                seg_override_base(ctxt, c),
-                                                c->regs[VCPU_REGS_RSI]),
-                                        &c->dst.val,
-                                        c->dst.bytes, ctxt->vcpu);
-                if (rc != X86EMUL_CONTINUE)
-                        goto done;
-                register_address_increment(c, &c->regs[VCPU_REGS_RSI],
-                                       (ctxt->eflags & EFLG_DF) ? -c->dst.bytes
-                                                           : c->dst.bytes);
-                register_address_increment(c, &c->regs[VCPU_REGS_RDI],
-                                       (ctxt->eflags & EFLG_DF) ? -c->dst.bytes
-                                                           : c->dst.bytes);
-                break;
+                goto mov;
         case 0xa6 ... 0xa7:     /* cmps */
-                c->src.type = OP_NONE; /* Disable writeback. */
-                c->src.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
-                c->src.ptr = (unsigned long *)register_address(c,
-                                       seg_override_base(ctxt, c),
-                                                   c->regs[VCPU_REGS_RSI]);
-                rc = ops->read_emulated((unsigned long)c->src.ptr,
-                                        &c->src.val,
-                                        c->src.bytes,
-                                        ctxt->vcpu);
-                if (rc != X86EMUL_CONTINUE)
-                        goto done;
-
                 c->dst.type = OP_NONE; /* Disable writeback. */
-                c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
-                c->dst.ptr = (unsigned long *)register_address(c,
-                                                   es_base(ctxt),
-                                                   c->regs[VCPU_REGS_RDI]);
-                rc = ops->read_emulated((unsigned long)c->dst.ptr,
-                                        &c->dst.val,
-                                        c->dst.bytes,
-                                        ctxt->vcpu);
-                if (rc != X86EMUL_CONTINUE)
-                        goto done;
-
                 DPRINTF("cmps: mem1=0x%p mem2=0x%p\n", c->src.ptr, c->dst.ptr);
-
-                emulate_2op_SrcV("cmp", c->src, c->dst, ctxt->eflags);
-
-                register_address_increment(c, &c->regs[VCPU_REGS_RSI],
-                                       (ctxt->eflags & EFLG_DF) ? -c->src.bytes
-                                                                  : c->src.bytes);
-                register_address_increment(c, &c->regs[VCPU_REGS_RDI],
-                                       (ctxt->eflags & EFLG_DF) ? -c->dst.bytes
-                                                                  : c->dst.bytes);
-
-                break;
+                goto cmp;
         case 0xaa ... 0xab:     /* stos */
-                c->dst.type = OP_MEM;
-                c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
-                c->dst.ptr = (unsigned long *)register_address(c,
-                                                   es_base(ctxt),
-                                                   c->regs[VCPU_REGS_RDI]);
                 c->dst.val = c->regs[VCPU_REGS_RAX];
-                register_address_increment(c, &c->regs[VCPU_REGS_RDI],
-                                       (ctxt->eflags & EFLG_DF) ? -c->dst.bytes
-                                                           : c->dst.bytes);
                 break;
         case 0xac ... 0xad:     /* lods */
-                c->dst.type = OP_REG;
-                c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
-                c->dst.ptr = (unsigned long *)&c->regs[VCPU_REGS_RAX];
-                rc = ops->read_emulated(register_address(c,
-                                                seg_override_base(ctxt, c),
-                                                c->regs[VCPU_REGS_RSI]),
-                                        &c->dst.val,
-                                        c->dst.bytes,
-                                        ctxt->vcpu);
-                if (rc != X86EMUL_CONTINUE)
-                        goto done;
-                register_address_increment(c, &c->regs[VCPU_REGS_RSI],
-                                       (ctxt->eflags & EFLG_DF) ? -c->dst.bytes
-                                                           : c->dst.bytes);
-                break;
+                goto mov;
         case 0xae ... 0xaf:     /* scas */
                 DPRINTF("Urk! I don't handle SCAS.\n");
                 goto cannot_emulate;
@@ -2277,7 +2834,7 @@ special_insn:
                 break;
         case 0xcb:              /* ret far */
                 rc = emulate_ret_far(ctxt, ops);
-                if (rc)
+                if (rc != X86EMUL_CONTINUE)
                         goto done;
                 break;
         case 0xd0 ... 0xd1:     /* Grp2 */
@@ -2290,14 +2847,10 @@ special_insn:
                 break;
         case 0xe4:      /* inb */
         case 0xe5:      /* in */
-                port = c->src.val;
-                io_dir_in = 1;
-                goto do_io;
+                goto do_io_in;
         case 0xe6: /* outb */
         case 0xe7: /* out */
-                port = c->src.val;
-                io_dir_in = 0;
-                goto do_io;
+                goto do_io_out;
         case 0xe8: /* call (near) */ {
                 long int rel = c->src.val;
                 c->src.val = (unsigned long) c->eip;
@@ -2308,8 +2861,9 @@ special_insn:
         case 0xe9: /* jmp rel */
                 goto jmp;
         case 0xea: /* jmp far */
-                if (kvm_load_segment_descriptor(ctxt->vcpu, c->src2.val,
-                                                VCPU_SREG_CS))
+        jump_far:
+                if (load_segment_descriptor(ctxt, ops, c->src2.val,
+                                            VCPU_SREG_CS))
                         goto done;
 
                 c->eip = c->src.val;
@@ -2321,25 +2875,29 @@ special_insn:
                 break;
         case 0xec: /* in al,dx */
         case 0xed: /* in (e/r)ax,dx */
-                port = c->regs[VCPU_REGS_RDX];
-                io_dir_in = 1;
-                goto do_io;
+                c->src.val = c->regs[VCPU_REGS_RDX];
+        do_io_in:
+                c->dst.bytes = min(c->dst.bytes, 4u);
+                if (!emulator_io_permited(ctxt, ops, c->src.val, c->dst.bytes)) {
+                        kvm_inject_gp(ctxt->vcpu, 0);
+                        goto done;
+                }
+                if (!pio_in_emulated(ctxt, ops, c->dst.bytes, c->src.val,
+                                     &c->dst.val))
+                        goto done; /* IO is needed */
+                break;
         case 0xee: /* out al,dx */
         case 0xef: /* out (e/r)ax,dx */
-                port = c->regs[VCPU_REGS_RDX];
-                io_dir_in = 0;
-        do_io:
-                if (!emulator_io_permited(ctxt, ops, port,
-                                          (c->d & ByteOp) ? 1 : c->op_bytes)) {
+                c->src.val = c->regs[VCPU_REGS_RDX];
+        do_io_out:
+                c->dst.bytes = min(c->dst.bytes, 4u);
+                if (!emulator_io_permited(ctxt, ops, c->src.val, c->dst.bytes)) {
                         kvm_inject_gp(ctxt->vcpu, 0);
                         goto done;
                 }
-                if (kvm_emulate_pio(ctxt->vcpu, io_dir_in,
-                                   (c->d & ByteOp) ? 1 : c->op_bytes,
-                                   port) != 0) {
-                        c->eip = saved_eip;
-                        goto cannot_emulate;
-                }
+                ops->pio_out_emulated(c->dst.bytes, c->src.val, &c->dst.val, 1,
+                                      ctxt->vcpu);
+                c->dst.type = OP_NONE;  /* Disable writeback. */
                 break;
         case 0xf4:              /* hlt */
                 ctxt->vcpu->arch.halt_request = 1;
@@ -2350,16 +2908,15 @@ special_insn:
                 c->dst.type = OP_NONE;  /* Disable writeback. */
                 break;
         case 0xf6 ... 0xf7:     /* Grp3 */
-                rc = emulate_grp3(ctxt, ops);
-                if (rc != 0)
-                        goto done;
+                if (!emulate_grp3(ctxt, ops))
+                        goto cannot_emulate;
                 break;
         case 0xf8: /* clc */
                 ctxt->eflags &= ~EFLG_CF;
                 c->dst.type = OP_NONE;  /* Disable writeback. */
                 break;
         case 0xfa: /* cli */
-                if (emulator_bad_iopl(ctxt))
+                if (emulator_bad_iopl(ctxt, ops))
                         kvm_inject_gp(ctxt->vcpu, 0);
                 else {
                         ctxt->eflags &= ~X86_EFLAGS_IF;
@@ -2367,10 +2924,10 @@ special_insn:
                 }
                 break;
         case 0xfb: /* sti */
-                if (emulator_bad_iopl(ctxt))
+                if (emulator_bad_iopl(ctxt, ops))
                         kvm_inject_gp(ctxt->vcpu, 0);
                 else {
-                        toggle_interruptibility(ctxt, X86_SHADOW_INT_STI);
+                        toggle_interruptibility(ctxt, KVM_X86_SHADOW_INT_STI);
                         ctxt->eflags |= X86_EFLAGS_IF;
                         c->dst.type = OP_NONE;  /* Disable writeback. */
                 }
@@ -2383,28 +2940,55 @@ special_insn:
                 ctxt->eflags |= EFLG_DF;
                 c->dst.type = OP_NONE;  /* Disable writeback. */
                 break;
-        case 0xfe ... 0xff:     /* Grp4/Grp5 */
+        case 0xfe: /* Grp4 */
+        grp45:
                 rc = emulate_grp45(ctxt, ops);
-                if (rc != 0)
+                if (rc != X86EMUL_CONTINUE)
                         goto done;
                 break;
+        case 0xff: /* Grp5 */
+                if (c->modrm_reg == 5)
+                        goto jump_far;
+                goto grp45;
         }
 
 writeback:
         rc = writeback(ctxt, ops);
-        if (rc != 0)
+        if (rc != X86EMUL_CONTINUE)
                 goto done;
 
+        /*
+         * restore dst type in case the decoding will be reused
+         * (happens for string instruction )
+         */
+        c->dst.type = saved_dst_type;
+
+        if ((c->d & SrcMask) == SrcSI)
+                string_addr_inc(ctxt, seg_override_base(ctxt, c), VCPU_REGS_RSI,
+                                &c->src);
+
+        if ((c->d & DstMask) == DstDI)
+                string_addr_inc(ctxt, es_base(ctxt), VCPU_REGS_RDI, &c->dst);
+
+        if (c->rep_prefix && (c->d & String)) {
+                struct read_cache *rc = &ctxt->decode.io_read;
+                register_address_increment(c, &c->regs[VCPU_REGS_RCX], -1);
+                /*
+                 * Re-enter guest when pio read ahead buffer is empty or,
+                 * if it is not used, after each 1024 iteration.
+                 */
+                if ((rc->end == 0 && !(c->regs[VCPU_REGS_RCX] & 0x3ff)) ||
+                    (rc->end != 0 && rc->end == rc->pos))
+                        ctxt->restart = false;
+        }
+
         /* Commit shadow register state. */
         memcpy(ctxt->vcpu->arch.regs, c->regs, sizeof c->regs);
         kvm_rip_write(ctxt->vcpu, c->eip);
+        ops->set_rflags(ctxt->vcpu, ctxt->eflags);
 
 done:
-        if (rc == X86EMUL_UNHANDLEABLE) {
-                c->eip = saved_eip;
-                return -1;
-        }
-        return 0;
+        return (rc == X86EMUL_UNHANDLEABLE) ? -1 : 0;
 
 twobyte_insn:
         switch (c->b) {
@@ -2418,18 +3002,18 @@ twobyte_insn:
                                 goto cannot_emulate;
 
                         rc = kvm_fix_hypercall(ctxt->vcpu);
-                        if (rc)
+                        if (rc != X86EMUL_CONTINUE)
                                 goto done;
 
                         /* Let the processor re-execute the fixed hypercall */
-                        c->eip = kvm_rip_read(ctxt->vcpu);
+                        c->eip = ctxt->eip;
                         /* Disable writeback. */
                         c->dst.type = OP_NONE;
                         break;
                 case 2: /* lgdt */
                         rc = read_descriptor(ctxt, ops, c->src.ptr,
                                              &size, &address, c->op_bytes);
-                        if (rc)
+                        if (rc != X86EMUL_CONTINUE)
                                 goto done;
                         realmode_lgdt(ctxt->vcpu, size, address);
                         /* Disable writeback. */
@@ -2440,7 +3024,7 @@ twobyte_insn:
                                 switch (c->modrm_rm) {
                                 case 1:
                                         rc = kvm_fix_hypercall(ctxt->vcpu);
-                                        if (rc)
+                                        if (rc != X86EMUL_CONTINUE)
                                                 goto done;
                                         break;
                                 default:
@@ -2450,7 +3034,7 @@ twobyte_insn:
                                 rc = read_descriptor(ctxt, ops, c->src.ptr,
                                                      &size, &address,
                                                      c->op_bytes);
-                                if (rc)
+                                if (rc != X86EMUL_CONTINUE)
                                         goto done;
                                 realmode_lidt(ctxt->vcpu, size, address);
                         }
@@ -2459,15 +3043,18 @@ twobyte_insn:
                         break;
                 case 4: /* smsw */
                         c->dst.bytes = 2;
-                        c->dst.val = realmode_get_cr(ctxt->vcpu, 0);
+                        c->dst.val = ops->get_cr(0, ctxt->vcpu);
                         break;
                 case 6: /* lmsw */
-                        realmode_lmsw(ctxt->vcpu, (u16)c->src.val,
-                                      &ctxt->eflags);
+                        ops->set_cr(0, (ops->get_cr(0, ctxt->vcpu) & ~0x0ful) |
+                                    (c->src.val & 0x0f), ctxt->vcpu);
                         c->dst.type = OP_NONE;
                         break;
+                case 5: /* not defined */
+                        kvm_queue_exception(ctxt->vcpu, UD_VECTOR);
+                        goto done;
                 case 7: /* invlpg*/
-                        emulate_invlpg(ctxt->vcpu, memop);
+                        emulate_invlpg(ctxt->vcpu, c->modrm_ea);
                         /* Disable writeback. */
                         c->dst.type = OP_NONE;
                         break;
@@ -2493,54 +3080,54 @@ twobyte_insn:
                 c->dst.type = OP_NONE;
                 break;
         case 0x20: /* mov cr, reg */
-                if (c->modrm_mod != 3)
-                        goto cannot_emulate;
-                c->regs[c->modrm_rm] =
-                                realmode_get_cr(ctxt->vcpu, c->modrm_reg);
+                switch (c->modrm_reg) {
+                case 1:
+                case 5 ... 7:
+                case 9 ... 15:
+                        kvm_queue_exception(ctxt->vcpu, UD_VECTOR);
+                        goto done;
+                }
+                c->regs[c->modrm_rm] = ops->get_cr(c->modrm_reg, ctxt->vcpu);
                 c->dst.type = OP_NONE;  /* no writeback */
                 break;
         case 0x21: /* mov from dr to reg */
-                if (c->modrm_mod != 3)
-                        goto cannot_emulate;
-                rc = emulator_get_dr(ctxt, c->modrm_reg, &c->regs[c->modrm_rm]);
-                if (rc)
-                        goto cannot_emulate;
+                if ((ops->get_cr(4, ctxt->vcpu) & X86_CR4_DE) &&
+                    (c->modrm_reg == 4 || c->modrm_reg == 5)) {
+                        kvm_queue_exception(ctxt->vcpu, UD_VECTOR);
+                        goto done;
+                }
+                emulator_get_dr(ctxt, c->modrm_reg, &c->regs[c->modrm_rm]);
                 c->dst.type = OP_NONE;  /* no writeback */
                 break;
         case 0x22: /* mov reg, cr */
-                if (c->modrm_mod != 3)
-                        goto cannot_emulate;
-                realmode_set_cr(ctxt->vcpu,
-                                c->modrm_reg, c->modrm_val, &ctxt->eflags);
+                ops->set_cr(c->modrm_reg, c->modrm_val, ctxt->vcpu);
                 c->dst.type = OP_NONE;
                 break;
         case 0x23: /* mov from reg to dr */
-                if (c->modrm_mod != 3)
-                        goto cannot_emulate;
-                rc = emulator_set_dr(ctxt, c->modrm_reg,
-                                     c->regs[c->modrm_rm]);
-                if (rc)
-                        goto cannot_emulate;
+                if ((ops->get_cr(4, ctxt->vcpu) & X86_CR4_DE) &&
+                    (c->modrm_reg == 4 || c->modrm_reg == 5)) {
+                        kvm_queue_exception(ctxt->vcpu, UD_VECTOR);
+                        goto done;
+                }
+                emulator_set_dr(ctxt, c->modrm_reg, c->regs[c->modrm_rm]);
                 c->dst.type = OP_NONE;  /* no writeback */
                 break;
         case 0x30:
                 /* wrmsr */
                 msr_data = (u32)c->regs[VCPU_REGS_RAX]
                         | ((u64)c->regs[VCPU_REGS_RDX] << 32);
-                rc = kvm_set_msr(ctxt->vcpu, c->regs[VCPU_REGS_RCX], msr_data);
-                if (rc) {
+                if (kvm_set_msr(ctxt->vcpu, c->regs[VCPU_REGS_RCX], msr_data)) {
                         kvm_inject_gp(ctxt->vcpu, 0);
-                        c->eip = kvm_rip_read(ctxt->vcpu);
+                        goto done;
                 }
                 rc = X86EMUL_CONTINUE;
                 c->dst.type = OP_NONE;
                 break;
         case 0x32:
                 /* rdmsr */
-                rc = kvm_get_msr(ctxt->vcpu, c->regs[VCPU_REGS_RCX], &msr_data);
-                if (rc) {
+                if (kvm_get_msr(ctxt->vcpu, c->regs[VCPU_REGS_RCX], &msr_data)) {
                         kvm_inject_gp(ctxt->vcpu, 0);
-                        c->eip = kvm_rip_read(ctxt->vcpu);
+                        goto done;
                 } else {
                         c->regs[VCPU_REGS_RAX] = (u32)msr_data;
                         c->regs[VCPU_REGS_RDX] = msr_data >> 32;
@@ -2577,7 +3164,7 @@ twobyte_insn:
                 break;
         case 0xa1:       /* pop fs */
                 rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_FS);
-                if (rc != 0)
+                if (rc != X86EMUL_CONTINUE)
                         goto done;
                 break;
         case 0xa3:
@@ -2596,7 +3183,7 @@ twobyte_insn:
                 break;
         case 0xa9:      /* pop gs */
                 rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_GS);
-                if (rc != 0)
+                if (rc != X86EMUL_CONTINUE)
                         goto done;
                 break;
         case 0xab:
@@ -2668,16 +3255,14 @@ twobyte_insn:
                                                         (u64) c->src.val;
                 break;
         case 0xc7:              /* Grp9 (cmpxchg8b) */
-                rc = emulate_grp9(ctxt, ops, memop);
-                if (rc != 0)
+                rc = emulate_grp9(ctxt, ops);
+                if (rc != X86EMUL_CONTINUE)
                         goto done;
-                c->dst.type = OP_NONE;
                 break;
         }
         goto writeback;
 
 cannot_emulate:
         DPRINTF("Cannot emulate %02x\n", c->b);
-        c->eip = saved_eip;
         return -1;
 }