KVM: x86 emulator: don't update vcpu state if instruction is restarted

No need to update vcpu state since instruction is in the middle of the
emulation.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

1 files changed, 13 insertions, 18 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 33deb75f16ee..3cbe8032394a 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4057,32 +4057,27 @@ restart:
                 return handle_emulation_failure(vcpu);
         }
 
-        toggle_interruptibility(vcpu, vcpu->arch.emulate_ctxt.interruptibility);
-        kvm_x86_ops->set_rflags(vcpu, vcpu->arch.emulate_ctxt.eflags);
-        memcpy(vcpu->arch.regs, c->regs, sizeof c->regs);
-        kvm_rip_write(vcpu, vcpu->arch.emulate_ctxt.eip);
+        r = EMULATE_DONE;
 
-        if (vcpu->arch.emulate_ctxt.exception >= 0) {
+        if (vcpu->arch.emulate_ctxt.exception >= 0)
                 inject_emulated_exception(vcpu);
-                return EMULATE_DONE;
-        }
-
-        if (vcpu->arch.pio.count) {
+        else if (vcpu->arch.pio.count) {
                 if (!vcpu->arch.pio.in)
                         vcpu->arch.pio.count = 0;
-                return EMULATE_DO_MMIO;
-        }
-
-        if (vcpu->mmio_needed) {
+                r = EMULATE_DO_MMIO;
+        } else if (vcpu->mmio_needed) {
                 if (vcpu->mmio_is_write)
                         vcpu->mmio_needed = 0;
-                return EMULATE_DO_MMIO;
-        }
-
-        if (vcpu->arch.emulate_ctxt.restart)
+                r = EMULATE_DO_MMIO;
+        } else if (vcpu->arch.emulate_ctxt.restart)
                 goto restart;
 
-        return EMULATE_DONE;
+        toggle_interruptibility(vcpu, vcpu->arch.emulate_ctxt.interruptibility);
+        kvm_x86_ops->set_rflags(vcpu, vcpu->arch.emulate_ctxt.eflags);
+        memcpy(vcpu->arch.regs, c->regs, sizeof c->regs);
+        kvm_rip_write(vcpu, vcpu->arch.emulate_ctxt.eip);
+
+        return r;
 }
 EXPORT_SYMBOL_GPL(emulate_instruction);