KVM: Call x86_decode_insn() only when needed
Move emulate_ctxt to kvm_vcpu to keep emulate context when we exit from kvm
module. Call x86_decode_insn() only when needed. Modify x86_emulate_insn() to
not modify the context if it must be re-entered.
Signed-off-by: Laurent Vivier <Laurent.Vivier@bull.net>
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/drivers/kvm/x86_emulate.c b/drivers/kvm/x86_emulate.c
index c191093..dc9d2a8 100644
--- a/drivers/kvm/x86_emulate.c
+++ b/drivers/kvm/x86_emulate.c
@@ -913,10 +913,19 @@
unsigned long cr2 = ctxt->cr2;
int no_wb = 0;
u64 msr_data;
+ unsigned long saved_eip = 0;
unsigned long _eflags = ctxt->eflags;
struct decode_cache *c = &ctxt->decode;
int rc = 0;
+ /* Shadow copy of register state. Committed on successful emulation.
+ * NOTE: we can copy them from vcpu as x86_decode_insn() doesn't
+ * modify them.
+ */
+
+ memcpy(c->regs, ctxt->vcpu->regs, sizeof c->regs);
+ saved_eip = c->eip;
+
if ((c->d & ModRM) && (c->modrm_mod != 3))
cr2 = c->modrm_ea;
@@ -1250,7 +1259,11 @@
ctxt->vcpu->rip = c->eip;
done:
- return (rc == X86EMUL_UNHANDLEABLE) ? -1 : 0;
+ if (rc == X86EMUL_UNHANDLEABLE) {
+ c->eip = saved_eip;
+ return -1;
+ }
+ return 0;
special_insn:
if (c->twobyte)
@@ -1305,8 +1318,10 @@
register_address(ctxt->es_base,
c->regs[VCPU_REGS_RDI]),
c->rep_prefix,
- c->regs[VCPU_REGS_RDX]) == 0)
+ c->regs[VCPU_REGS_RDX]) == 0) {
+ c->eip = saved_eip;
return -1;
+ }
return 0;
case 0x6e: /* outsb */
case 0x6f: /* outsw/outsd */
@@ -1321,8 +1336,10 @@
ctxt->ds_base,
c->regs[VCPU_REGS_RSI]),
c->rep_prefix,
- c->regs[VCPU_REGS_RDX]) == 0)
+ c->regs[VCPU_REGS_RDX]) == 0) {
+ c->eip = saved_eip;
return -1;
+ }
return 0;
case 0x70 ... 0x7f: /* jcc (short) */ {
int rel = insn_fetch(s8, 1, c->eip);
@@ -1711,5 +1728,6 @@
cannot_emulate:
DPRINTF("Cannot emulate %02x\n", c->b);
+ c->eip = saved_eip;
return -1;
}