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>

1 files changed, 15 insertions, 12 deletions

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 816d23185fb8..427dbc14fae9 100644
--- 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)) {