diff options
| -rw-r--r-- | arch/x86/kvm/x86.c | 15 |
1 files changed, 11 insertions, 4 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 3c995483b405..e317559df489 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -10138,15 +10138,22 @@ out: static void process_nmi(struct kvm_vcpu *vcpu) { - unsigned limit = 2; + unsigned int limit; /* - * x86 is limited to one NMI running, and one NMI pending after it. - * If an NMI is already in progress, limit further NMIs to just one. - * Otherwise, allow two (and we'll inject the first one immediately). + * x86 is limited to one NMI pending, but because KVM can't react to + * incoming NMIs as quickly as bare metal, e.g. if the vCPU is + * scheduled out, KVM needs to play nice with two queued NMIs showing + * up at the same time. To handle this scenario, allow two NMIs to be + * (temporarily) pending so long as NMIs are not blocked and KVM is not + * waiting for a previous NMI injection to complete (which effectively + * blocks NMIs). KVM will immediately inject one of the two NMIs, and + * will request an NMI window to handle the second NMI. */ if (static_call(kvm_x86_get_nmi_mask)(vcpu) || vcpu->arch.nmi_injected) limit = 1; + else + limit = 2; vcpu->arch.nmi_pending += atomic_xchg(&vcpu->arch.nmi_queued, 0); vcpu->arch.nmi_pending = min(vcpu->arch.nmi_pending, limit); |