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>

diff --git a/drivers/kvm/x86_emulate.c b/drivers/kvm/x86_emulate.c
index 84e536603f5ae109621c488950a87b6149a93e65..53377f0b202e540f5318588291cf14f36f31ddad 100644 (file)
--- 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;