KVM: VMX: Handle mmio emulation when guest state is invalid

If emulate_invalid_guest_state is enabled, the emulator is called
when guest state is invalid.  Until now, we reported an mmio failure
when emulate_instruction() returned EMULATE_DO_MMIO.  This patch adds
the case where emulate_instruction() failed and an MMIO emulation
is needed.

Signed-off-by: Guillaume Thouvenin <guillaume.thouvenin@ext.bull.net>
Signed-off-by: Avi Kivity <avi@redhat.com>

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 816d23185fb82754c6e006887bb8147377f80950..427dbc14fae9380b4e6c8a62f481b8351b820cad 100644 (file)
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3052,16 +3052,12 @@ static void handle_invalid_guest_state(struct kvm_vcpu *vcpu,
        while (!guest_state_valid(vcpu)) {
                err = emulate_instruction(vcpu, kvm_run, 0, 0, 0);
 
-               switch (err) {
-                       case EMULATE_DONE:
-                               break;
-                       case EMULATE_DO_MMIO:
-                               kvm_report_emulation_failure(vcpu, "mmio");
-                               /* TODO: Handle MMIO */
-                               return;
-                       default:
-                               kvm_report_emulation_failure(vcpu, "emulation failure");
-                               return;
+               if (err == EMULATE_DO_MMIO)
+                       break;
+
+               if (err != EMULATE_DONE) {
+                       kvm_report_emulation_failure(vcpu, "emulation failure");
+                       return;
                }
 
                if (signal_pending(current))
@@ -3073,8 +3069,10 @@ static void handle_invalid_guest_state(struct kvm_vcpu *vcpu,
        local_irq_disable();
        preempt_disable();
 
-       /* Guest state should be valid now, no more emulation should be needed */
-       vmx->emulation_required = 0;
+       /* Guest state should be valid now except if we need to
+        * emulate an MMIO */
+       if (guest_state_valid(vcpu))
+               vmx->emulation_required = 0;
 }
 
 /*
@@ -3121,6 +3119,11 @@ static int kvm_handle_exit(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
        KVMTRACE_3D(VMEXIT, vcpu, exit_reason, (u32)kvm_rip_read(vcpu),
                    (u32)((u64)kvm_rip_read(vcpu) >> 32), entryexit);
 
+       /* If we need to emulate an MMIO from handle_invalid_guest_state
+        * we just return 0 */
+       if (vmx->emulation_required && emulate_invalid_guest_state)
+               return 0;
+
        /* Access CR3 don't cause VMExit in paging mode, so we need
         * to sync with guest real CR3. */
        if (vm_need_ept() && is_paging(vcpu)) {