KVM: emulate: rework seg_override

x86_decode_insn already sets a default for seg_override,
so remove it from the zeroed area. Also replace set/get functions
with direct access to the field.

Signed-off-by: Bandan Das <bsd@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 16 insertions, 25 deletions

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 3e9bbdc4c76a..08badf638fb0 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -514,12 +514,6 @@ static u32 desc_limit_scaled(struct desc_struct *desc)
         return desc->g ? (limit << 12) | 0xfff : limit;
 }
 
-static void set_seg_override(struct x86_emulate_ctxt *ctxt, int seg)
-{
-        ctxt->has_seg_override = true;
-        ctxt->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)
@@ -528,14 +522,6 @@ static unsigned long seg_base(struct x86_emulate_ctxt *ctxt, int seg)
         return ctxt->ops->get_cached_segment_base(ctxt, seg);
 }
 
-static unsigned seg_override(struct x86_emulate_ctxt *ctxt)
-{
-        if (!ctxt->has_seg_override)
-                return 0;
-
-        return ctxt->seg_override;
-}
-
 static int emulate_exception(struct x86_emulate_ctxt *ctxt, int vec,
                              u32 error, bool valid)
 {
@@ -4169,7 +4155,7 @@ static int decode_operand(struct x86_emulate_ctxt *ctxt, struct operand *op,
                 op->bytes = (ctxt->d & ByteOp) ? 1 : ctxt->op_bytes;
                 op->addr.mem.ea =
                         register_address(ctxt, reg_read(ctxt, VCPU_REGS_RSI));
-                op->addr.mem.seg = seg_override(ctxt);
+                op->addr.mem.seg = ctxt->seg_override;
                 op->val = 0;
                 op->count = 1;
                 break;
@@ -4180,7 +4166,7 @@ static int decode_operand(struct x86_emulate_ctxt *ctxt, struct operand *op,
                         register_address(ctxt,
                                 reg_read(ctxt, VCPU_REGS_RBX) +
                                 (reg_read(ctxt, VCPU_REGS_RAX) & 0xff));
-                op->addr.mem.seg = seg_override(ctxt);
+                op->addr.mem.seg = ctxt->seg_override;
                 op->val = 0;
                 break;
         case OpImmFAddr:
@@ -4227,6 +4213,7 @@ int x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len)
         int mode = ctxt->mode;
         int def_op_bytes, def_ad_bytes, goffset, simd_prefix;
         bool op_prefix = false;
+        bool has_seg_override = false;
         struct opcode opcode;
 
         ctxt->memop.type = OP_NONE;
@@ -4280,11 +4267,13 @@ int x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len)
                 case 0x2e:      /* CS override */
                 case 0x36:      /* SS override */
                 case 0x3e:      /* DS override */
-                        set_seg_override(ctxt, (ctxt->b >> 3) & 3);
+                        has_seg_override = true;
+                        ctxt->seg_override = (ctxt->b >> 3) & 3;
                         break;
                 case 0x64:      /* FS override */
                 case 0x65:      /* GS override */
-                        set_seg_override(ctxt, ctxt->b & 7);
+                        has_seg_override = true;
+                        ctxt->seg_override = ctxt->b & 7;
                         break;
                 case 0x40 ... 0x4f: /* REX */
                         if (mode != X86EMUL_MODE_PROT64)
@@ -4422,17 +4411,19 @@ done_prefixes:
         /* ModRM and SIB bytes. */
         if (ctxt->d & ModRM) {
                 rc = decode_modrm(ctxt, &ctxt->memop);
-                if (!ctxt->has_seg_override)
-                        set_seg_override(ctxt, ctxt->modrm_seg);
+                if (!has_seg_override) {
+                        has_seg_override = true;
+                        ctxt->seg_override = ctxt->modrm_seg;
+                }
         } else if (ctxt->d & MemAbs)
                 rc = decode_abs(ctxt, &ctxt->memop);
         if (rc != X86EMUL_CONTINUE)
                 goto done;
 
-        if (!ctxt->has_seg_override)
-                set_seg_override(ctxt, VCPU_SREG_DS);
+        if (!has_seg_override)
+                ctxt->seg_override = VCPU_SREG_DS;
 
-        ctxt->memop.addr.mem.seg = seg_override(ctxt);
+        ctxt->memop.addr.mem.seg = ctxt->seg_override;
 
         if (ctxt->memop.type == OP_MEM && ctxt->ad_bytes != 8)
                 ctxt->memop.addr.mem.ea = (u32)ctxt->memop.addr.mem.ea;
@@ -4534,8 +4525,8 @@ static int fastop(struct x86_emulate_ctxt *ctxt, void (*fop)(struct fastop *))
 
 void init_decode_cache(struct x86_emulate_ctxt *ctxt)
 {
-        memset(&ctxt->has_seg_override, 0,
-               (void *)&ctxt->modrm - (void *)&ctxt->has_seg_override);
+        memset(&ctxt->rip_relative, 0,
+               (void *)&ctxt->modrm - (void *)&ctxt->rip_relative);
 
         ctxt->io_read.pos = 0;
         ctxt->io_read.end = 0;