KVM: x86 emulator: Move rep processing before instruction execution

Currently rep processing is handled somewhere in the middle of instruction
processing.  Move it to a sensible place.

Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 36 insertions, 34 deletions

diff --git a/drivers/kvm/x86_emulate.c b/drivers/kvm/x86_emulate.c
index 84e536603f5a..53377f0b202e 100644
--- a/drivers/kvm/x86_emulate.c
+++ b/drivers/kvm/x86_emulate.c
@@ -64,6 +64,7 @@
 #define Mov         (1<<7)
 #define BitOp       (1<<8)
 #define MemAbs      (1<<9)      /* Memory operand is absolute displacement */
+#define String      (1<<10)     /* String instruction (rep capable) */
 
 static u16 opcode_table[256] = {
         /* 0x00 - 0x07 */
@@ -133,12 +134,12 @@ static u16 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, ImplicitOps | Mov,
-        ByteOp | ImplicitOps, ImplicitOps,
+        ByteOp | ImplicitOps | Mov | String, ImplicitOps | Mov | String,
+        ByteOp | ImplicitOps | String, ImplicitOps | String,
         /* 0xA8 - 0xAF */
-        0, 0, ByteOp | ImplicitOps | Mov, ImplicitOps | Mov,
-        ByteOp | ImplicitOps | Mov, ImplicitOps | Mov,
-        ByteOp | ImplicitOps, ImplicitOps,
+        0, 0, ByteOp | ImplicitOps | Mov | String, ImplicitOps | Mov | String,
+        ByteOp | ImplicitOps | Mov | String, ImplicitOps | Mov | String,
+        ByteOp | ImplicitOps | String, ImplicitOps | String,
         /* 0xB0 - 0xBF */
         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
         /* 0xC0 - 0xC7 */
@@ -1228,6 +1229,36 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
         if (((c->d & ModRM) && (c->modrm_mod != 3)) || (c->d & MemAbs))
                 memop = c->modrm_ea;
 
+        if (c->rep_prefix && (c->d & String)) {
+                /* All REP prefixes have the same first termination condition */
+                if (c->regs[VCPU_REGS_RCX] == 0) {
+                        ctxt->vcpu->rip = c->eip;
+                        goto done;
+                }
+                /* The second termination condition only applies for REPE
+                 * and REPNE. Test if the repeat string operation prefix is
+                 * REPE/REPZ or REPNE/REPNZ and if it's the case it tests the
+                 * corresponding termination condition according to:
+                 *      - if REPE/REPZ and ZF = 0 then done
+                 *      - if REPNE/REPNZ and ZF = 1 then done
+                 */
+                if ((c->b == 0xa6) || (c->b == 0xa7) ||
+                                (c->b == 0xae) || (c->b == 0xaf)) {
+                        if ((c->rep_prefix == REPE_PREFIX) &&
+                                ((ctxt->eflags & EFLG_ZF) == 0)) {
+                                        ctxt->vcpu->rip = c->eip;
+                                        goto done;
+                        }
+                        if ((c->rep_prefix == REPNE_PREFIX) &&
+                                ((ctxt->eflags & EFLG_ZF) == EFLG_ZF)) {
+                                ctxt->vcpu->rip = c->eip;
+                                goto done;
+                        }
+                }
+                c->regs[VCPU_REGS_RCX]--;
+                c->eip = ctxt->vcpu->rip;
+        }
+
         if (c->src.type == OP_MEM) {
                 c->src.ptr = (unsigned long *)memop;
                 c->src.val = 0;
@@ -1534,35 +1565,6 @@ special_insn:
                 c->dst.type = OP_NONE;  /* Disable writeback. */
                 break;
         }
-        if (c->rep_prefix) {
-                /* All REP prefixes have the same first termination condition */
-                if (c->regs[VCPU_REGS_RCX] == 0) {
-                        ctxt->vcpu->rip = c->eip;
-                        goto done;
-                }
-                /* The second termination condition only applies for REPE
-                 * and REPNE. Test if the repeat string operation prefix is
-                 * REPE/REPZ or REPNE/REPNZ and if it's the case it tests the
-                 * corresponding termination condition according to:
-                 *      - if REPE/REPZ and ZF = 0 then done
-                 *      - if REPNE/REPNZ and ZF = 1 then done
-                 */
-                if ((c->b == 0xa6) || (c->b == 0xa7) ||
-                                (c->b == 0xae) || (c->b == 0xaf)) {
-                        if ((c->rep_prefix == REPE_PREFIX) &&
-                                ((ctxt->eflags & EFLG_ZF) == 0)) {
-                                        ctxt->vcpu->rip = c->eip;
-                                        goto done;
-                        }
-                        if ((c->rep_prefix == REPNE_PREFIX) &&
-                                ((ctxt->eflags & EFLG_ZF) == EFLG_ZF)) {
-                                ctxt->vcpu->rip = c->eip;
-                                goto done;
-                        }
-                }
-                c->regs[VCPU_REGS_RCX]--;
-                c->eip = ctxt->vcpu->rip;
-        }
         switch (c->b) {
         case 0xa4 ... 0xa5:     /* movs */
                 c->dst.type = OP_MEM;