From: Sean Christopherson seanjc@google.com
commit 5aede752a839904059c2b5d68be0dc4501c6c15f upstream.
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 Reviewed-by: Paolo Bonzini pbonzini@redhat.com Reviewed-by: Maxim Levitsky mlevitsk@redhat.com Signed-off-by: Sean Christopherson seanjc@google.com Message-Id: 20230106011306.85230-5-seanjc@google.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kvm/svm/avic.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-)
--- a/arch/x86/kvm/svm/avic.c +++ b/arch/x86/kvm/svm/avic.c @@ -502,14 +502,18 @@ int avic_incomplete_ipi_interception(str 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(str */ 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;