From fb88c3f1e9df7b1452123c6d181584da65db4092 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Mon, 22 Nov 2021 19:43:10 -0500 Subject: [PATCH] KVM: x86: check PIR even for vCPUs with disabled APICv BugLink: https://bugs.launchpad.net/bugs/1956791 commit 37c4dbf337c5c2cdb24365ffae6ed70ac1e74d7a upstream. The IRTE for an assigned device can trigger a POSTED_INTR_VECTOR even if APICv is disabled on the vCPU that receives it. In that case, the interrupt will just cause a vmexit and leave the ON bit set together with the PIR bit corresponding to the interrupt. Right now, the interrupt would not be delivered until APICv is re-enabled. However, fixing this is just a matter of always doing the PIR->IRR synchronization, even if the vCPU has temporarily disabled APICv. This is not a problem for performance, or if anything it is an improvement. First, in the common case where vcpu->arch.apicv_active is true, one fewer check has to be performed. Second, static_call_cond will elide the function call if APICv is not present or disabled. Finally, in the case for AMD hardware we can remove the sync_pir_to_irr callback: it is only needed for apic_has_interrupt_for_ppr, and that function already has a fallback for !APICv. Cc: stable@vger.kernel.org Co-developed-by: Sean Christopherson Signed-off-by: Sean Christopherson Reviewed-by: Maxim Levitsky Reviewed-by: David Matlack Message-Id: <20211123004311.2954158-4-pbonzini@redhat.com> Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman Signed-off-by: Kamal Mostafa Signed-off-by: Stefan Bader --- arch/x86/kvm/lapic.c | 2 +- arch/x86/kvm/svm/svm.c | 1 - arch/x86/kvm/x86.c | 18 +++++++++--------- 3 files changed, 10 insertions(+), 11 deletions(-) diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 17fa4ab1b834..8cc30fd0fdbf 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -704,7 +704,7 @@ static void pv_eoi_clr_pending(struct kvm_vcpu *vcpu) static int apic_has_interrupt_for_ppr(struct kvm_lapic *apic, u32 ppr) { int highest_irr; - if (apic->vcpu->arch.apicv_active) + if (kvm_x86_ops.sync_pir_to_irr) highest_irr = static_call(kvm_x86_sync_pir_to_irr)(apic->vcpu); else highest_irr = apic_find_highest_irr(apic); diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index fa49b433c42c..17594391c06f 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -4530,7 +4530,6 @@ static struct kvm_x86_ops svm_x86_ops __initdata = { .load_eoi_exitmap = svm_load_eoi_exitmap, .hwapic_irr_update = svm_hwapic_irr_update, .hwapic_isr_update = svm_hwapic_isr_update, - .sync_pir_to_irr = kvm_lapic_find_highest_irr, .apicv_post_state_restore = avic_post_state_restore, .set_tss_addr = svm_set_tss_addr, diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index ee0e827a0445..ba182596cc01 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4300,8 +4300,7 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu) static int kvm_vcpu_ioctl_get_lapic(struct kvm_vcpu *vcpu, struct kvm_lapic_state *s) { - if (vcpu->arch.apicv_active) - static_call(kvm_x86_sync_pir_to_irr)(vcpu); + static_call_cond(kvm_x86_sync_pir_to_irr)(vcpu); return kvm_apic_get_state(vcpu, s); } @@ -9176,8 +9175,7 @@ static void vcpu_scan_ioapic(struct kvm_vcpu *vcpu) if (irqchip_split(vcpu->kvm)) kvm_scan_ioapic_routes(vcpu, vcpu->arch.ioapic_handled_vectors); else { - if (vcpu->arch.apicv_active) - static_call(kvm_x86_sync_pir_to_irr)(vcpu); + 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); } @@ -9435,10 +9433,12 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) /* * This handles the case where a posted interrupt was - * notified with kvm_vcpu_kick. + * notified with kvm_vcpu_kick. Assigned devices can + * use the POSTED_INTR_VECTOR even if APICv is disabled, + * so do it even if APICv is disabled on this vCPU. */ - if (kvm_lapic_enabled(vcpu) && vcpu->arch.apicv_active) - static_call(kvm_x86_sync_pir_to_irr)(vcpu); + if (kvm_lapic_enabled(vcpu)) + static_call_cond(kvm_x86_sync_pir_to_irr)(vcpu); if (kvm_vcpu_exit_request(vcpu)) { vcpu->mode = OUTSIDE_GUEST_MODE; @@ -9476,8 +9476,8 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) if (likely(exit_fastpath != EXIT_FASTPATH_REENTER_GUEST)) break; - if (kvm_lapic_enabled(vcpu) && vcpu->arch.apicv_active) - static_call(kvm_x86_sync_pir_to_irr)(vcpu); + if (kvm_lapic_enabled(vcpu)) + static_call_cond(kvm_x86_sync_pir_to_irr)(vcpu); if (unlikely(kvm_vcpu_exit_request(vcpu))) { exit_fastpath = EXIT_FASTPATH_EXIT_HANDLED; -- 2.39.2