6.1-stable review patch. If anyone has any objections, please let me know.
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From: Sean Christopherson seanjc@google.com
commit f3ced000a2df53f4b12849e121769045a81a3b22 upstream.
Sync pending posted interrupts to the IRR prior to re-scanning I/O APIC routes, irrespective of whether the I/O APIC is emulated by userspace or by KVM. If a level-triggered interrupt routed through the I/O APIC is pending or in-service for a vCPU, KVM needs to intercept EOIs on said vCPU even if the vCPU isn't the destination for the new routing, e.g. if servicing an interrupt using the old routing races with I/O APIC reconfiguration.
Commit fceb3a36c29a ("KVM: x86: ioapic: Fix level-triggered EOI and userspace I/OAPIC reconfigure race") fixed the common cases, but kvm_apic_pending_eoi() only checks if an interrupt is in the local APIC's IRR or ISR, i.e. misses the uncommon case where an interrupt is pending in the PIR.
Failure to intercept EOI can manifest as guest hangs with Windows 11 if the guest uses the RTC as its timekeeping source, e.g. if the VMM doesn't expose a more modern form of time to the guest.
Cc: stable@vger.kernel.org Cc: Adamos Ttofari attofari@amazon.de Cc: Raghavendra Rao Ananta rananta@google.com Reviewed-by: Jim Mattson jmattson@google.com Signed-off-by: Sean Christopherson seanjc@google.com Message-ID: 20240611014845.82795-1-seanjc@google.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kvm/x86.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-)
--- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -10523,13 +10523,12 @@ static void vcpu_scan_ioapic(struct kvm_
bitmap_zero(vcpu->arch.ioapic_handled_vectors, 256);
+ static_call_cond(kvm_x86_sync_pir_to_irr)(vcpu); + if (irqchip_split(vcpu->kvm)) kvm_scan_ioapic_routes(vcpu, vcpu->arch.ioapic_handled_vectors); - else { - static_call_cond(kvm_x86_sync_pir_to_irr)(vcpu); - if (ioapic_in_kernel(vcpu->kvm)) - kvm_ioapic_scan_entry(vcpu, vcpu->arch.ioapic_handled_vectors); - } + else if (ioapic_in_kernel(vcpu->kvm)) + kvm_ioapic_scan_entry(vcpu, vcpu->arch.ioapic_handled_vectors);
if (is_guest_mode(vcpu)) vcpu->arch.load_eoi_exitmap_pending = true;