KVM: nVMX: Fix vmx_check_nested_events() return value in case an event was reinjected to L2

vmx_check_nested_events() should return -EBUSY only in case there is a
pending L1 event which requires a VMExit from L2 to L1 but such a
VMExit is currently blocked. Such VMExits are blocked either
because nested_run_pending=1 or an event was reinjected to L2.
vmx_check_nested_events() should return 0 in case there are no
pending L1 events which requires a VMExit from L2 to L1 or if
a VMExit from L2 to L1 was done internally.

However, upstream commit which introduced blocking in case an event was
reinjected to L2 (commit acc9ab601327 ("KVM: nVMX: Fix pending events
injection")) contains a bug: It returns -EBUSY even if there are no
pending L1 events which requires VMExit from L2 to L1.

This commit fix this issue.

Fixes: acc9ab601327 ("KVM: nVMX: Fix pending events injection")

Signed-off-by: Liran Alon <liran.alon@oracle.com>
Reviewed-by: Nikita Leshenko <nikita.leshchenko@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>

1 files changed, 6 insertions, 7 deletions

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 10474d26a000..be4724b5d434 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -11105,13 +11105,12 @@ static int vmx_check_nested_events(struct kvm_vcpu *vcpu, bool external_intr)
 {
         struct vcpu_vmx *vmx = to_vmx(vcpu);
         unsigned long exit_qual;
-
-        if (kvm_event_needs_reinjection(vcpu))
-                return -EBUSY;
+        bool block_nested_events =
+            vmx->nested.nested_run_pending || kvm_event_needs_reinjection(vcpu);
 
         if (vcpu->arch.exception.pending &&
                 nested_vmx_check_exception(vcpu, &exit_qual)) {
-                if (vmx->nested.nested_run_pending)
+                if (block_nested_events)
                         return -EBUSY;
                 nested_vmx_inject_exception_vmexit(vcpu, exit_qual);
                 vcpu->arch.exception.pending = false;
@@ -11120,14 +11119,14 @@ static int vmx_check_nested_events(struct kvm_vcpu *vcpu, bool external_intr)
 
         if (nested_cpu_has_preemption_timer(get_vmcs12(vcpu)) &&
             vmx->nested.preemption_timer_expired) {
-                if (vmx->nested.nested_run_pending)
+                if (block_nested_events)
                         return -EBUSY;
                 nested_vmx_vmexit(vcpu, EXIT_REASON_PREEMPTION_TIMER, 0, 0);
                 return 0;
         }
 
         if (vcpu->arch.nmi_pending && nested_exit_on_nmi(vcpu)) {
-                if (vmx->nested.nested_run_pending)
+                if (block_nested_events)
                         return -EBUSY;
                 nested_vmx_vmexit(vcpu, EXIT_REASON_EXCEPTION_NMI,
                                   NMI_VECTOR | INTR_TYPE_NMI_INTR |
@@ -11143,7 +11142,7 @@ static int vmx_check_nested_events(struct kvm_vcpu *vcpu, bool external_intr)
 
         if ((kvm_cpu_has_interrupt(vcpu) || external_intr) &&
             nested_exit_on_intr(vcpu)) {
-                if (vmx->nested.nested_run_pending)
+                if (block_nested_events)
                         return -EBUSY;
                 nested_vmx_vmexit(vcpu, EXIT_REASON_EXTERNAL_INTERRUPT, 0, 0);
                 return 0;