KVM: x86: Evaluate ability to inject SMI/NMI/IRQ after potential VM-Exit

Determine whether or not new events can be injected after checking nested
events.  If a VM-Exit occurred during nested event handling, any previous
event that needed re-injection is gone from's KVM perspective; the event
is captured in the vmc*12 VM-Exit information, but doesn't exist in terms
of what needs to be done for entry to L1.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Link: https://lore.kernel.org/r/20220830231614.3580124-19-seanjc@google.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index e864f1b..458c7e3 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9723,7 +9723,7 @@ static void kvm_inject_exception(struct kvm_vcpu *vcpu)
 
 static int inject_pending_event(struct kvm_vcpu *vcpu, bool *req_immediate_exit)
 {
-       bool can_inject = !kvm_event_needs_reinjection(vcpu);
+       bool can_inject;
        int r;
 
        /*
@@ -9788,7 +9788,13 @@ static int inject_pending_event(struct kvm_vcpu *vcpu, bool *req_immediate_exit)
        if (r < 0)
                goto out;
 
-       /* try to inject new event if pending */
+       /*
+        * New events, other than exceptions, cannot be injected if KVM needs
+        * to re-inject a previous event.  See above comments on re-injecting
+        * for why pending exceptions get priority.
+        */
+       can_inject = !kvm_event_needs_reinjection(vcpu);
+
        if (vcpu->arch.exception.pending) {
                /*
                 * Fault-class exceptions, except #DBs, set RF=1 in the RFLAGS