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/kvm_main.c b/drivers/kvm/kvm_main.c
index 800ab50..7104836 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -1251,45 +1251,56 @@
int emulate_instruction(struct kvm_vcpu *vcpu,
struct kvm_run *run,
unsigned long cr2,
- u16 error_code)
+ u16 error_code,
+ int no_decode)
{
- struct x86_emulate_ctxt emulate_ctxt;
- int r;
- int cs_db, cs_l;
+ int r = 0;
vcpu->mmio_fault_cr2 = cr2;
kvm_x86_ops->cache_regs(vcpu);
- kvm_x86_ops->get_cs_db_l_bits(vcpu, &cs_db, &cs_l);
-
- emulate_ctxt.vcpu = vcpu;
- emulate_ctxt.eflags = kvm_x86_ops->get_rflags(vcpu);
- emulate_ctxt.cr2 = cr2;
- emulate_ctxt.mode = (emulate_ctxt.eflags & X86_EFLAGS_VM)
- ? X86EMUL_MODE_REAL : cs_l
- ? X86EMUL_MODE_PROT64 : cs_db
- ? X86EMUL_MODE_PROT32 : X86EMUL_MODE_PROT16;
-
- if (emulate_ctxt.mode == X86EMUL_MODE_PROT64) {
- emulate_ctxt.cs_base = 0;
- emulate_ctxt.ds_base = 0;
- emulate_ctxt.es_base = 0;
- emulate_ctxt.ss_base = 0;
- } else {
- emulate_ctxt.cs_base = get_segment_base(vcpu, VCPU_SREG_CS);
- emulate_ctxt.ds_base = get_segment_base(vcpu, VCPU_SREG_DS);
- emulate_ctxt.es_base = get_segment_base(vcpu, VCPU_SREG_ES);
- emulate_ctxt.ss_base = get_segment_base(vcpu, VCPU_SREG_SS);
- }
-
- emulate_ctxt.gs_base = get_segment_base(vcpu, VCPU_SREG_GS);
- emulate_ctxt.fs_base = get_segment_base(vcpu, VCPU_SREG_FS);
-
vcpu->mmio_is_write = 0;
vcpu->pio.string = 0;
- r = x86_decode_insn(&emulate_ctxt, &emulate_ops);
+
+ if (!no_decode) {
+ int cs_db, cs_l;
+ kvm_x86_ops->get_cs_db_l_bits(vcpu, &cs_db, &cs_l);
+
+ vcpu->emulate_ctxt.vcpu = vcpu;
+ vcpu->emulate_ctxt.eflags = kvm_x86_ops->get_rflags(vcpu);
+ vcpu->emulate_ctxt.cr2 = cr2;
+ vcpu->emulate_ctxt.mode =
+ (vcpu->emulate_ctxt.eflags & X86_EFLAGS_VM)
+ ? X86EMUL_MODE_REAL : cs_l
+ ? X86EMUL_MODE_PROT64 : cs_db
+ ? X86EMUL_MODE_PROT32 : X86EMUL_MODE_PROT16;
+
+ if (vcpu->emulate_ctxt.mode == X86EMUL_MODE_PROT64) {
+ vcpu->emulate_ctxt.cs_base = 0;
+ vcpu->emulate_ctxt.ds_base = 0;
+ vcpu->emulate_ctxt.es_base = 0;
+ vcpu->emulate_ctxt.ss_base = 0;
+ } else {
+ vcpu->emulate_ctxt.cs_base =
+ get_segment_base(vcpu, VCPU_SREG_CS);
+ vcpu->emulate_ctxt.ds_base =
+ get_segment_base(vcpu, VCPU_SREG_DS);
+ vcpu->emulate_ctxt.es_base =
+ get_segment_base(vcpu, VCPU_SREG_ES);
+ vcpu->emulate_ctxt.ss_base =
+ get_segment_base(vcpu, VCPU_SREG_SS);
+ }
+
+ vcpu->emulate_ctxt.gs_base =
+ get_segment_base(vcpu, VCPU_SREG_GS);
+ vcpu->emulate_ctxt.fs_base =
+ get_segment_base(vcpu, VCPU_SREG_FS);
+
+ r = x86_decode_insn(&vcpu->emulate_ctxt, &emulate_ops);
+ }
+
if (r == 0)
- r = x86_emulate_insn(&emulate_ctxt, &emulate_ops);
+ r = x86_emulate_insn(&vcpu->emulate_ctxt, &emulate_ops);
if (vcpu->pio.string)
return EMULATE_DO_MMIO;
@@ -1313,7 +1324,7 @@
}
kvm_x86_ops->decache_regs(vcpu);
- kvm_x86_ops->set_rflags(vcpu, emulate_ctxt.eflags);
+ kvm_x86_ops->set_rflags(vcpu, vcpu->emulate_ctxt.eflags);
if (vcpu->mmio_is_write) {
vcpu->mmio_needed = 0;
@@ -2055,7 +2066,7 @@
vcpu->mmio_read_completed = 1;
vcpu->mmio_needed = 0;
r = emulate_instruction(vcpu, kvm_run,
- vcpu->mmio_fault_cr2, 0);
+ vcpu->mmio_fault_cr2, 0, 1);
if (r == EMULATE_DO_MMIO) {
/*
* Read-modify-write. Back to userspace.