KVM: x86 emulator: move all decoding process to function x86_decode_insn()

Split the decoding process into a new function x86_decode_insn().

Signed-off-by: Laurent Vivier <Laurent.Vivier@bull.net>
Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 53 insertions, 24 deletions

diff --git a/drivers/kvm/x86_emulate.c b/drivers/kvm/x86_emulate.c
index d7026cb8fc70..540589c5d427 100644
--- a/drivers/kvm/x86_emulate.c
+++ b/drivers/kvm/x86_emulate.c
@@ -517,20 +517,16 @@ static int test_cc(unsigned int condition, unsigned int flags)
 }
 
 int
-x86_emulate_memop(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
+x86_decode_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
 {
         struct decode_cache *c = &ctxt->decode;
         u8 sib, rex_prefix = 0;
         unsigned int i;
         int rc = 0;
-        unsigned long cr2 = ctxt->cr2;
         int mode = ctxt->mode;
         int index_reg = 0, base_reg = 0, scale, rip_relative = 0;
-        int no_wb = 0;
-        u64 msr_data;
 
         /* Shadow copy of register state. Committed on successful emulation. */
-        unsigned long _eflags = ctxt->eflags;
 
         memset(c, 0, sizeof(struct decode_cache));
         c->eip = ctxt->vcpu->rip;
@@ -622,8 +618,10 @@ done_prefixes:
                 }
 
                 /* Unrecognised? */
-                if (c->d == 0)
-                        goto cannot_emulate;
+                if (c->d == 0) {
+                        DPRINTF("Cannot emulate %02x\n", c->b);
+                        return -1;
+                }
         }
 
         /* ModRM and SIB bytes. */
@@ -776,7 +774,6 @@ done_prefixes:
                 }
                 if (c->ad_bytes != 8)
                         c->modrm_ea = (u32)c->modrm_ea;
-                cr2 = c->modrm_ea;
         modrm_done:
                 ;
         }
@@ -838,13 +835,6 @@ done_prefixes:
                         break;
                 }
                 c->src.type = OP_MEM;
-                c->src.ptr = (unsigned long *)cr2;
-                c->src.val = 0;
-                if ((rc = ops->read_emulated((unsigned long)c->src.ptr,
-                                           &c->src.val,
-                                           c->src.bytes, ctxt->vcpu)) != 0)
-                        goto done;
-                c->src.orig_val = c->src.val;
                 break;
         case SrcImm:
                 c->src.type = OP_IMM;
@@ -877,7 +867,7 @@ done_prefixes:
         switch (c->d & DstMask) {
         case ImplicitOps:
                 /* Special instructions do their own operand decoding. */
-                goto special_insn;
+                return 0;
         case DstReg:
                 c->dst.type = OP_REG;
                 if ((c->d & ByteOp)
@@ -905,14 +895,54 @@ done_prefixes:
                 }
                 break;
         case DstMem:
-                c->dst.type = OP_MEM;
-                c->dst.ptr = (unsigned long *)cr2;
-                c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
-                c->dst.val = 0;
                 if ((c->d & ModRM) && c->modrm_mod == 3) {
                         c->dst.type = OP_REG;
                         break;
                 }
+                c->dst.type = OP_MEM;
+                break;
+        }
+
+done:
+        return (rc == X86EMUL_UNHANDLEABLE) ? -1 : 0;
+}
+
+int
+x86_emulate_memop(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
+{
+        unsigned long cr2 = ctxt->cr2;
+        int no_wb = 0;
+        u64 msr_data;
+        unsigned long _eflags = ctxt->eflags;
+        struct decode_cache *c = &ctxt->decode;
+        int rc;
+
+        rc = x86_decode_insn(ctxt, ops);
+        if (rc)
+                return rc;
+
+        if ((c->d & ModRM) && (c->modrm_mod != 3))
+                cr2 = c->modrm_ea;
+
+        if (c->src.type == OP_MEM) {
+                c->src.ptr = (unsigned long *)cr2;
+                c->src.val = 0;
+                if ((rc = ops->read_emulated((unsigned long)c->src.ptr,
+                                             &c->src.val,
+                                             c->src.bytes,
+                                             ctxt->vcpu)) != 0)
+                        goto done;
+                c->src.orig_val = c->src.val;
+        }
+
+        if ((c->d & DstMask) == ImplicitOps)
+                goto special_insn;
+
+
+        if (c->dst.type == OP_MEM) {
+                c->dst.ptr = (unsigned long *)cr2;
+                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);
 
@@ -925,7 +955,6 @@ done_prefixes:
                                            &c->dst.val,
                                           c->dst.bytes, ctxt->vcpu)) != 0))
                         goto done;
-                break;
         }
         c->dst.orig_val = c->dst.val;
 
@@ -983,7 +1012,7 @@ done_prefixes:
                 emulate_2op_SrcV("cmp", c->src, c->dst, _eflags);
                 break;
         case 0x63:              /* movsxd */
-                if (mode != X86EMUL_MODE_PROT64)
+                if (ctxt->mode != X86EMUL_MODE_PROT64)
                         goto cannot_emulate;
                 c->dst.val = (s32) c->src.val;
                 break;
@@ -1041,7 +1070,7 @@ done_prefixes:
                 break;
         case 0x8f:              /* pop (sole member of Grp1a) */
                 /* 64-bit mode: POP always pops a 64-bit operand. */
-                if (mode == X86EMUL_MODE_PROT64)
+                if (ctxt->mode == X86EMUL_MODE_PROT64)
                         c->dst.bytes = 8;
                 if ((rc = ops->read_std(register_address(
                                                    ctxt->ss_base,
@@ -1152,7 +1181,7 @@ done_prefixes:
                         break;
                 case 6: /* push */
                         /* 64-bit mode: PUSH always pushes a 64-bit operand. */
-                        if (mode == X86EMUL_MODE_PROT64) {
+                        if (ctxt->mode == X86EMUL_MODE_PROT64) {
                                 c->dst.bytes = 8;
                                 if ((rc = ops->read_std(
                                                  (unsigned long)c->dst.ptr,