Messages in this thread | | | Date | Mon, 5 Sep 2022 23:59:52 +0200 | Subject | Re: [PATCH v2 03/23] KVM: SVM: Process ICR on AVIC IPI delivery failure due to invalid target | From | Paolo Bonzini <> |
| |
On 9/3/22 02:22, Sean Christopherson wrote: > Emulate ICR writes on AVIC IPI failures due to invalid targets using the > same logic as failures due to invalid types. AVIC acceleration fails if > _any_ of the targets are invalid, and crucially VM-Exits before sending > IPIs to targets that _are_ valid. In logical mode, the destination is a > bitmap, i.e. a single IPI can target multiple logical IDs. Doing nothing > causes KVM to drop IPIs if at least one target is valid and at least one > target is invalid. > > Fixes: 18f40c53e10f ("svm: Add VMEXIT handlers for AVIC") > Cc: stable@vger.kernel.org > Signed-off-by: Sean Christopherson <seanjc@google.com> > Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> > --- > arch/x86/kvm/svm/avic.c | 16 +++++++++------- > 1 file changed, 9 insertions(+), 7 deletions(-) > > diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c > index 4fbef2af1efc..6a3d225eb02c 100644 > --- a/arch/x86/kvm/svm/avic.c > +++ b/arch/x86/kvm/svm/avic.c > @@ -502,14 +502,18 @@ int avic_incomplete_ipi_interception(struct kvm_vcpu *vcpu) > trace_kvm_avic_incomplete_ipi(vcpu->vcpu_id, icrh, icrl, id, index); > > switch (id) { > + case AVIC_IPI_FAILURE_INVALID_TARGET: > case AVIC_IPI_FAILURE_INVALID_INT_TYPE: > /* > * Emulate IPIs that are not handled by AVIC hardware, which > - * only virtualizes Fixed, Edge-Triggered INTRs. The exit is > - * a trap, e.g. ICR holds the correct value and RIP has been > - * advanced, KVM is responsible only for emulating the IPI. > - * Sadly, hardware may sometimes leave the BUSY flag set, in > - * which case KVM needs to emulate the ICR write as well in > + * only virtualizes Fixed, Edge-Triggered INTRs, and falls over > + * if _any_ targets are invalid, e.g. if the logical mode mask > + * is a superset of running vCPUs. > + * > + * The exit is a trap, e.g. ICR holds the correct value and RIP > + * has been advanced, KVM is responsible only for emulating the > + * IPI. Sadly, hardware may sometimes leave the BUSY flag set, > + * in which case KVM needs to emulate the ICR write as well in > * order to clear the BUSY flag. > */ > if (icrl & APIC_ICR_BUSY) > @@ -525,8 +529,6 @@ int avic_incomplete_ipi_interception(struct kvm_vcpu *vcpu) > */ > avic_kick_target_vcpus(vcpu->kvm, apic, icrl, icrh, index); > break; > - case AVIC_IPI_FAILURE_INVALID_TARGET: > - break; > case AVIC_IPI_FAILURE_INVALID_BACKING_PAGE: > WARN_ONCE(1, "Invalid backing page\n"); > break;
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
| |