3 files changed, 60 insertions, 67 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index d1db5aa5c7f4..f726ba79fd3a 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2126,27 +2126,6 @@ int emulate_instruction(struct kvm_vcpu *vcpu,
                         ? X86EMUL_MODE_PROT64 : cs_db
                         ? X86EMUL_MODE_PROT32 : X86EMUL_MODE_PROT16;
 
-                if (vcpu->arch.emulate_ctxt.mode == X86EMUL_MODE_PROT64) {
-                        vcpu->arch.emulate_ctxt.cs_base = 0;
-                        vcpu->arch.emulate_ctxt.ds_base = 0;
-                        vcpu->arch.emulate_ctxt.es_base = 0;
-                        vcpu->arch.emulate_ctxt.ss_base = 0;
-                } else {
-                        vcpu->arch.emulate_ctxt.cs_base =
-                                        get_segment_base(vcpu, VCPU_SREG_CS);
-                        vcpu->arch.emulate_ctxt.ds_base =
-                                        get_segment_base(vcpu, VCPU_SREG_DS);
-                        vcpu->arch.emulate_ctxt.es_base =
-                                        get_segment_base(vcpu, VCPU_SREG_ES);
-                        vcpu->arch.emulate_ctxt.ss_base =
-                                        get_segment_base(vcpu, VCPU_SREG_SS);
-                }
-
-                vcpu->arch.emulate_ctxt.gs_base =
-                                        get_segment_base(vcpu, VCPU_SREG_GS);
-                vcpu->arch.emulate_ctxt.fs_base =
-                                        get_segment_base(vcpu, VCPU_SREG_FS);
-
                 r = x86_decode_insn(&vcpu->arch.emulate_ctxt, &emulate_ops);
 
                 /* Reject the instructions other than VMCALL/VMMCALL when
diff --git a/arch/x86/kvm/x86_emulate.c b/arch/x86/kvm/x86_emulate.c
index 38926b7da64a..18ca25c2d4a4 100644
--- a/arch/x86/kvm/x86_emulate.c
+++ b/arch/x86/kvm/x86_emulate.c
@@ -522,6 +522,39 @@ static inline void jmp_rel(struct decode_cache *c, int rel)
         register_address_increment(c, &c->eip, rel);
 }
 
+static void set_seg_override(struct decode_cache *c, int seg)
+{
+        c->has_seg_override = true;
+        c->seg_override = seg;
+}
+
+static unsigned long seg_base(struct x86_emulate_ctxt *ctxt, int seg)
+{
+        if (ctxt->mode == X86EMUL_MODE_PROT64 && seg < VCPU_SREG_FS)
+                return 0;
+
+        return kvm_x86_ops->get_segment_base(ctxt->vcpu, seg);
+}
+
+static unsigned long seg_override_base(struct x86_emulate_ctxt *ctxt,
+                                       struct decode_cache *c)
+{
+        if (!c->has_seg_override)
+                return 0;
+
+        return seg_base(ctxt, c->seg_override);
+}
+
+static unsigned long es_base(struct x86_emulate_ctxt *ctxt)
+{
+        return seg_base(ctxt, VCPU_SREG_ES);
+}
+
+static unsigned long ss_base(struct x86_emulate_ctxt *ctxt)
+{
+        return seg_base(ctxt, VCPU_SREG_SS);
+}
+
 static int do_fetch_insn_byte(struct x86_emulate_ctxt *ctxt,
                               struct x86_emulate_ops *ops,
                               unsigned long linear, u8 *dest)
@@ -735,8 +768,8 @@ static int decode_modrm(struct x86_emulate_ctxt *ctxt,
                 }
                 if (c->modrm_rm == 2 || c->modrm_rm == 3 ||
                     (c->modrm_rm == 6 && c->modrm_mod != 0))
-                        if (!c->override_base)
-                                c->override_base = &ctxt->ss_base;
+                        if (!c->has_seg_override)
+                                set_seg_override(c, VCPU_SREG_SS);
                 c->modrm_ea = (u16)c->modrm_ea;
         } else {
                 /* 32/64-bit ModR/M decode. */
@@ -807,6 +840,7 @@ x86_decode_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
 
         memset(c, 0, sizeof(struct decode_cache));
         c->eip = ctxt->vcpu->arch.rip;
+        ctxt->cs_base = seg_base(ctxt, VCPU_SREG_CS);
         memcpy(c->regs, ctxt->vcpu->arch.regs, sizeof c->regs);
 
         switch (mode) {
@@ -845,23 +879,15 @@ x86_decode_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
                                 /* switch between 2/4 bytes */
                                 c->ad_bytes = def_ad_bytes ^ 6;
                         break;
+                case 0x26:      /* ES override */
                 case 0x2e:      /* CS override */
-                        c->override_base = &ctxt->cs_base;
-                        break;
+                case 0x36:      /* SS override */
                 case 0x3e:      /* DS override */
-                        c->override_base = &ctxt->ds_base;
-                        break;
-                case 0x26:      /* ES override */
-                        c->override_base = &ctxt->es_base;
+                        set_seg_override(c, (c->b >> 3) & 3);
                         break;
                 case 0x64:      /* FS override */
-                        c->override_base = &ctxt->fs_base;
-                        break;
                 case 0x65:      /* GS override */
-                        c->override_base = &ctxt->gs_base;
-                        break;
-                case 0x36:      /* SS override */
-                        c->override_base = &ctxt->ss_base;
+                        set_seg_override(c, c->b & 7);
                         break;
                 case 0x40 ... 0x4f: /* REX */
                         if (mode != X86EMUL_MODE_PROT64)
@@ -933,15 +959,11 @@ done_prefixes:
         if (rc)
                 goto done;
 
-        if (!c->override_base)
-                c->override_base = &ctxt->ds_base;
-        if (mode == X86EMUL_MODE_PROT64 &&
-            c->override_base != &ctxt->fs_base &&
-            c->override_base != &ctxt->gs_base)
-                c->override_base = NULL;
+        if (!c->has_seg_override)
+                set_seg_override(c, VCPU_SREG_DS);
 
-        if (c->override_base && !(!c->twobyte && c->b == 0x8d))
-                c->modrm_ea += *c->override_base;
+        if (!(!c->twobyte && c->b == 0x8d))
+                c->modrm_ea += seg_override_base(ctxt, c);
 
         if (c->ad_bytes != 8)
                 c->modrm_ea = (u32)c->modrm_ea;
@@ -1043,7 +1065,7 @@ static inline void emulate_push(struct x86_emulate_ctxt *ctxt)
         c->dst.bytes = c->op_bytes;
         c->dst.val = c->src.val;
         register_address_increment(c, &c->regs[VCPU_REGS_RSP], -c->op_bytes);
-        c->dst.ptr = (void *) register_address(c, ctxt->ss_base,
+        c->dst.ptr = (void *) register_address(c, ss_base(ctxt),
                                                c->regs[VCPU_REGS_RSP]);
 }
 
@@ -1053,7 +1075,7 @@ static inline int emulate_grp1a(struct x86_emulate_ctxt *ctxt,
         struct decode_cache *c = &ctxt->decode;
         int rc;
 
-        rc = ops->read_std(register_address(c, ctxt->ss_base,
+        rc = ops->read_std(register_address(c, ss_base(ctxt),
                                             c->regs[VCPU_REGS_RSP]),
                            &c->dst.val, c->dst.bytes, ctxt->vcpu);
         if (rc != 0)
@@ -1375,11 +1397,11 @@ special_insn:
                 register_address_increment(c, &c->regs[VCPU_REGS_RSP],
                                            -c->op_bytes);
                 c->dst.ptr = (void *) register_address(
-                        c, ctxt->ss_base, c->regs[VCPU_REGS_RSP]);
+                        c, ss_base(ctxt), c->regs[VCPU_REGS_RSP]);
                 break;
         case 0x58 ... 0x5f: /* pop reg */
         pop_instruction:
-                if ((rc = ops->read_std(register_address(c, ctxt->ss_base,
+                if ((rc = ops->read_std(register_address(c, ss_base(ctxt),
                         c->regs[VCPU_REGS_RSP]), c->dst.ptr,
                         c->op_bytes, ctxt->vcpu)) != 0)
                         goto done;
@@ -1405,7 +1427,7 @@ special_insn:
                                 c->rep_prefix ?
                                 address_mask(c, c->regs[VCPU_REGS_RCX]) : 1,
                                 (ctxt->eflags & EFLG_DF),
-                                register_address(c, ctxt->es_base,
+                                register_address(c, es_base(ctxt),
                                                  c->regs[VCPU_REGS_RDI]),
                                 c->rep_prefix,
                                 c->regs[VCPU_REGS_RDX]) == 0) {
@@ -1421,9 +1443,8 @@ special_insn:
                                 c->rep_prefix ?
                                 address_mask(c, c->regs[VCPU_REGS_RCX]) : 1,
                                 (ctxt->eflags & EFLG_DF),
-                                register_address(c, c->override_base ?
-                                                        *c->override_base :
-                                                        ctxt->ds_base,
+                                         register_address(c,
+                                          seg_override_base(ctxt, c),
                                                  c->regs[VCPU_REGS_RSI]),
                                 c->rep_prefix,
                                 c->regs[VCPU_REGS_RDX]) == 0) {
@@ -1559,11 +1580,10 @@ special_insn:
                 c->dst.type = OP_MEM;
                 c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
                 c->dst.ptr = (unsigned long *)register_address(c,
-                                                   ctxt->es_base,
+                                                   es_base(ctxt),
                                                    c->regs[VCPU_REGS_RDI]);
                 if ((rc = ops->read_emulated(register_address(c,
-                      c->override_base ? *c->override_base :
-                                        ctxt->ds_base,
+                                           seg_override_base(ctxt, c),
                                         c->regs[VCPU_REGS_RSI]),
                                         &c->dst.val,
                                         c->dst.bytes, ctxt->vcpu)) != 0)
@@ -1579,8 +1599,7 @@ special_insn:
                 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,
-                                c->override_base ? *c->override_base :
-                                                   ctxt->ds_base,
+                                       seg_override_base(ctxt, c),
                                                    c->regs[VCPU_REGS_RSI]);
                 if ((rc = ops->read_emulated((unsigned long)c->src.ptr,
                                                 &c->src.val,
@@ -1591,7 +1610,7 @@ special_insn:
                 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,
-                                                   ctxt->es_base,
+                                                   es_base(ctxt),
                                                    c->regs[VCPU_REGS_RDI]);
                 if ((rc = ops->read_emulated((unsigned long)c->dst.ptr,
                                                 &c->dst.val,
@@ -1615,7 +1634,7 @@ special_insn:
                 c->dst.type = OP_MEM;
                 c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
                 c->dst.ptr = (unsigned long *)register_address(c,
-                                                   ctxt->es_base,
+                                                   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],
@@ -1627,8 +1646,7 @@ special_insn:
                 c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
                 c->dst.ptr = (unsigned long *)&c->regs[VCPU_REGS_RAX];
                 if ((rc = ops->read_emulated(register_address(c,
-                                c->override_base ? *c->override_base :
-                                                   ctxt->ds_base,
+                                                 seg_override_base(ctxt, c),
                                                  c->regs[VCPU_REGS_RSI]),
                                                  &c->dst.val,
                                                  c->dst.bytes,
diff --git a/include/asm-x86/kvm_x86_emulate.h b/include/asm-x86/kvm_x86_emulate.h
index 9fda4b35e195..4e8c1e48d91d 100644
--- a/include/asm-x86/kvm_x86_emulate.h
+++ b/include/asm-x86/kvm_x86_emulate.h
@@ -124,7 +124,8 @@ struct decode_cache {
         u8 rex_prefix;
         struct operand src;
         struct operand dst;
-        unsigned long *override_base;
+        bool has_seg_override;
+        u8 seg_override;
         unsigned int d;
         unsigned long regs[NR_VCPU_REGS];
         unsigned long eip;
@@ -151,12 +152,7 @@ struct x86_emulate_ctxt {
         /* Emulated execution mode, represented by an X86EMUL_MODE value. */
         int mode;
 
-        unsigned long cs_base;
-        unsigned long ds_base;
-        unsigned long es_base;
-        unsigned long ss_base;
-        unsigned long gs_base;
-        unsigned long fs_base;
+        u32 cs_base;
 
         /* decode cache */