Signed-off-by: Gleb Natapov <gleb@xxxxxxxxxx>
---
arch/x86/kvm/emulate.c | 42 +++++++++++++++++++++++++++++-------------
1 files changed, 29 insertions(+), 13 deletions(-)
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index f9f8353..d34d706 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -2921,6 +2921,32 @@ done:
return (rc == X86EMUL_UNHANDLEABLE) ? -1 : 0;
}
+static bool string_inst_completed(struct x86_emulate_ctxt *ctxt)
+{
+ struct decode_cache *c = &ctxt->decode;
+
+ /* All REP prefixes have the same first termination condition */
+ if (address_mask(c, c->regs[VCPU_REGS_RCX]) == 0)
+ return true;
+
+ /* 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))
+ && (((c->rep_prefix == REPE_PREFIX) &&
+ ((ctxt->eflags & EFLG_ZF) == 0))
+ || ((c->rep_prefix == REPNE_PREFIX) &&
+ ((ctxt->eflags & EFLG_ZF) == EFLG_ZF))))
+ return true;
+
+ return false;
+}
+
int
x86_emulate_insn(struct x86_emulate_ctxt *ctxt)
{
@@ -3395,19 +3421,9 @@ writeback:
if (c->rep_prefix && (c->d & String)) {
struct read_cache *r = &ctxt->decode.io_read;
register_address_increment(c, &c->regs[VCPU_REGS_RCX], -1);
- /* 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))
- && (((c->rep_prefix == REPE_PREFIX) &&
- ((ctxt->eflags & EFLG_ZF) == 0))
- || ((c->rep_prefix == REPNE_PREFIX) &&
- ((ctxt->eflags & EFLG_ZF) == EFLG_ZF))))
+
+
+ if (string_inst_completed(ctxt))
ctxt->restart = false;
/*
* Re-enter guest when pio read ahead buffer is empty or,
--
1.7.1
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