[PATCHv4 05/11] KVM: x86: Raise an event request when processing NMIs if an NMI is pending

Santosh Shukla
2023-02-27T08:52:03Z

From: Sean Christopherson <seanjc@google.com>

Don't raise KVM_REQ_EVENT if no NMIs are pending at the end of
process_nmi(). Finishing process_nmi() without a pending NMI will become
much more likely when KVM gains support for AMD's vNMI, which allows
pending vNMIs in hardware, i.e. doesn't require explicit injection.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Santosh Shukla <Santosh.Shukla@amd.com>
---
arch/x86/kvm/x86.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index f706621c35b8..1cd9cadc82af 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10148,7 +10148,9 @@ static void process_nmi(struct kvm_vcpu *vcpu)

vcpu->arch.nmi_pending += atomic_xchg(&vcpu->arch.nmi_queued, 0);
vcpu->arch.nmi_pending = min(vcpu->arch.nmi_pending, limit);
- kvm_make_request(KVM_REQ_EVENT, vcpu);
+
+ if (vcpu->arch.nmi_pending)
+ kvm_make_request(KVM_REQ_EVENT, vcpu);
}

void kvm_make_scan_ioapic_request_mask(struct kvm *kvm,
--
2.25.1