[Devel] [PATCH 06/11] KVM: x86: Fix nmi injection failure when vcpu got blocked

[Alexander Mikhalitsyn]

From: ZhuangYanying <ann.zhuangyanying at huawei.com>

When spin_lock_irqsave() deadlock occurs inside the guest, vcpu threads,
other than the lock-holding one, would enter into S state because of
pvspinlock. Then inject NMI via libvirt API "inject-nmi", the NMI could
not be injected into vm.

The reason is:
1 It sets nmi_queued to 1 when calling ioctl KVM_NMI in qemu, and sets
cpu->kvm_vcpu_dirty to true in do_inject_external_nmi() meanwhile.
2 It sets nmi_queued to 0 in process_nmi(), before entering guest, because
cpu->kvm_vcpu_dirty is true.

It's not enough just to check nmi_queued to decide whether to stay in
vcpu_block() or not. NMI should be injected immediately at any situation.
Add checking nmi_pending, and testing KVM_REQ_NMI replaces nmi_queued
in vm_vcpu_has_events().

Do the same change for SMIs.

Signed-off-by: Zhuang Yanying <ann.zhuangyanying at huawei.com>
Signed-off-by: Paolo Bonzini <pbonzini at redhat.com>
(cherry picked from commit 47a66eed99e6f231f4a1d261a9d493f4eee94829)

https://jira.sw.ru/browse/PSBM-139278

Signed-off-by: Alexander Mikhalitsyn <alexander.mikhalitsyn at virtuozzo.com>
---
 arch/x86/kvm/x86.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index e56d13b41bae..47d35eb43c86 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8810,10 +8810,13 @@ static inline bool kvm_vcpu_has_events(struct kvm_vcpu *vcpu)
 	if (vcpu->arch.pv.pv_unhalted)
 		return true;
 
-	if (atomic_read(&vcpu->arch.nmi_queued))
+	if (test_bit(KVM_REQ_NMI, &vcpu->requests) ||
+	    (vcpu->arch.nmi_pending &&
+	     kvm_x86_ops->nmi_allowed(vcpu)))
 		return true;
 
-	if (test_bit(KVM_REQ_SMI, &vcpu->requests))
+	if (test_bit(KVM_REQ_SMI, &vcpu->requests) ||
+	    (vcpu->arch.smi_pending && !is_smm(vcpu)))
 		return true;
 
 	if (kvm_arch_interrupt_allowed(vcpu) &&
-- 
2.36.1