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Subject[PATCH 16/54] KVM: x86 emulator: Move rep processing before instruction execution
Date
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>
---
drivers/kvm/x86_emulate.c | 70 +++++++++++++++++++++++----------------------
1 files changed, 36 insertions(+), 34 deletions(-)

diff --git a/drivers/kvm/x86_emulate.c b/drivers/kvm/x86_emulate.c
index 84e5366..53377f0 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;
--
1.5.3.7


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