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KVM: x86 emulator: lazily evaluate segment registers
[deliverable/linux.git] / arch / x86 / kvm / x86_emulate.c
diff --git a/arch/x86/kvm/x86_emulate.c b/arch/x86/kvm/x86_emulate.c
index c3a823174f3eadea1349e30fba333a488940293b..18ca25c2d4a4d7a7a3349479d2b653d72e76293b 100644 (file)
--- 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)
@@ -664,7 +697,7 @@ 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, rip_relative = 0;
+       int index_reg = 0, base_reg = 0, scale;
        int rc = 0;
 
        if (c->rex_prefix) {
@@ -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. */
@@ -754,7 +787,7 @@ static int decode_modrm(struct x86_emulate_ctxt *ctxt,
                                c->modrm_ea += c->regs[index_reg] << scale;
                } else if ((c->modrm_rm & 7) == 5 && c->modrm_mod == 0) {
                        if (ctxt->mode == X86EMUL_MODE_PROT64)
-                               rip_relative = 1;
+                               c->rip_relative = 1;
                } else
                        c->modrm_ea += c->regs[c->modrm_rm];
                switch (c->modrm_mod) {
@@ -770,22 +803,6 @@ static int decode_modrm(struct x86_emulate_ctxt *ctxt,
                        break;
                }
        }
-       if (rip_relative) {
-               c->modrm_ea += c->eip;
-               switch (c->d & SrcMask) {
-               case SrcImmByte:
-                       c->modrm_ea += 1;
-                       break;
-               case SrcImm:
-                       if (c->d & ByteOp)
-                               c->modrm_ea += 1;
-                       else
-                               if (c->op_bytes == 8)
-                                       c->modrm_ea += 4;
-                               else
-                                       c->modrm_ea += c->op_bytes;
-               }
-       }
 done:
        return rc;
 }
@@ -823,6 +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) {
@@ -861,23 +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)
@@ -949,15 +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->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;
@@ -1044,6 +1050,9 @@ done_prefixes:
                break;
        }
 
+       if (c->rip_relative)
+               c->modrm_ea += c->eip;
+
 done:
        return (rc == X86EMUL_UNHANDLEABLE) ? -1 : 0;
 }
@@ -1056,7 +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]);
 }
 
@@ -1066,7 +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)
@@ -1388,11 +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;
@@ -1418,7 +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) {
@@ -1434,9 +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) {
@@ -1572,11 +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)
@@ -1592,8 +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,
@@ -1604,7 +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,
@@ -1628,7 +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],
@@ -1640,8 +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,
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