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KVM: x86: Request event processing for exception VM-Exits

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Request event processing whenever kvm_queue_exception_vmexit() queues an
exception VM-Exit.  Most callers reach the helper through
kvm_multiple_exception(), which already sets KVM_REQ_EVENT, but nested
asynchronous page faults call it directly.

Without another event request, vcpu_enter_guest() skips
kvm_check_and_inject_events() and re-enters L2.  A subsequent VM-Exit can
clear the pending exception while reconstructing vectoring state, losing
the synthetic #PF VM-Exit.  The APF reason remains PAGE_NOT_PRESENT and a
later regular #PF can consume the stale value.

Setting KVM_REQ_EVENT in the common helper ensures that L1 receives the
queued VM-Exit before KVM re-enters L2.

Fixes: 7709aba8f7 ("KVM: x86: Morph pending exceptions to pending VM-Exits at queue time")
Cc: stable@vger.kernel.org
Signed-off-by: Loc Nguyen <loc@ryzome.com>
Link: https://patch.msgid.link/20261002053723.3275202-2-loc@ryzome.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Loc Nguyen 2026-10-02 05:42:54 +00:00 committed by Sean Christopherson
parent 34f749161d
commit 88b23a2e82
1 changed files with 2 additions and 0 deletions
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2
arch/x86/kvm/x86.c
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@ -456,6 +456,8 @@ static void kvm_queue_exception_vmexit(struct kvm_vcpu *vcpu, unsigned int vecto
{
struct kvm_queued_exception *ex = &vcpu->arch.exception_vmexit;
kvm_make_request(KVM_REQ_EVENT, vcpu);
ex->vector = vector;
ex->injected = false;
ex->pending = true;