From c300ab9f08df9e4b9f39d53a0691e234330df124 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Thu, 23 Apr 2020 14:08:58 -0400 Subject: KVM: x86: Replace late check_nested_events() hack with more precise fix Add an argument to interrupt_allowed and nmi_allowed, to checking if interrupt injection is blocked. Use the hook to handle the case where an interrupt arrives between check_nested_events() and the injection logic. Drop the retry of check_nested_events() that hack-a-fixed the same condition. Blocking injection is also a bit of a hack, e.g. KVM should do exiting and non-exiting interrupt processing in a single pass, but it's a more precise hack. The old comment is also misleading, e.g. KVM_REQ_EVENT is purely an optimization, setting it on every run loop (which KVM doesn't do) should not affect functionality, only performance. Signed-off-by: Sean Christopherson Message-Id: <20200423022550.15113-13-sean.j.christopherson@intel.com> [Extend to SVM, add SMI and NMI. Even though NMI and SMI cannot come asynchronously right now, making the fix generic is easy and removes a special case. - Paolo] Signed-off-by: Paolo Bonzini --- arch/x86/kvm/x86.c | 36 ++++++++++++------------------------ 1 file changed, 12 insertions(+), 24 deletions(-) (limited to 'arch/x86/kvm/x86.c') diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index cb250f16bdf5..ec20368ac025 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -7766,32 +7766,20 @@ static int inject_pending_event(struct kvm_vcpu *vcpu) if (kvm_event_needs_reinjection(vcpu)) return 0; - if (vcpu->arch.smi_pending && kvm_x86_ops.smi_allowed(vcpu)) { + if (vcpu->arch.smi_pending && + kvm_x86_ops.smi_allowed(vcpu, true)) { vcpu->arch.smi_pending = false; ++vcpu->arch.smi_count; enter_smm(vcpu); - } else if (vcpu->arch.nmi_pending && kvm_x86_ops.nmi_allowed(vcpu)) { + } else if (vcpu->arch.nmi_pending && + kvm_x86_ops.nmi_allowed(vcpu, true)) { --vcpu->arch.nmi_pending; vcpu->arch.nmi_injected = true; kvm_x86_ops.set_nmi(vcpu); - } else if (kvm_cpu_has_injectable_intr(vcpu)) { - /* - * Because interrupts can be injected asynchronously, we are - * calling check_nested_events again here to avoid a race condition. - * See https://lkml.org/lkml/2014/7/2/60 for discussion about this - * proposal and current concerns. Perhaps we should be setting - * KVM_REQ_EVENT only on certain events and not unconditionally? - */ - if (is_guest_mode(vcpu)) { - r = kvm_x86_ops.nested_ops->check_events(vcpu); - if (r != 0) - return r; - } - if (kvm_x86_ops.interrupt_allowed(vcpu)) { - kvm_queue_interrupt(vcpu, kvm_cpu_get_interrupt(vcpu), - false); - kvm_x86_ops.set_irq(vcpu); - } + } else if (kvm_cpu_has_injectable_intr(vcpu) && + kvm_x86_ops.interrupt_allowed(vcpu, true)) { + kvm_queue_interrupt(vcpu, kvm_cpu_get_interrupt(vcpu), false); + kvm_x86_ops.set_irq(vcpu); } return 0; @@ -10203,12 +10191,12 @@ static inline bool kvm_vcpu_has_events(struct kvm_vcpu *vcpu) if (kvm_test_request(KVM_REQ_NMI, vcpu) || (vcpu->arch.nmi_pending && - kvm_x86_ops.nmi_allowed(vcpu))) + kvm_x86_ops.nmi_allowed(vcpu, false))) return true; if (kvm_test_request(KVM_REQ_SMI, vcpu) || (vcpu->arch.smi_pending && - kvm_x86_ops.smi_allowed(vcpu))) + kvm_x86_ops.smi_allowed(vcpu, false))) return true; if (kvm_arch_interrupt_allowed(vcpu) && @@ -10260,7 +10248,7 @@ int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu) int kvm_arch_interrupt_allowed(struct kvm_vcpu *vcpu) { - return kvm_x86_ops.interrupt_allowed(vcpu); + return kvm_x86_ops.interrupt_allowed(vcpu, false); } unsigned long kvm_get_linear_rip(struct kvm_vcpu *vcpu) @@ -10425,7 +10413,7 @@ bool kvm_can_do_async_pf(struct kvm_vcpu *vcpu) * If interrupts are off we cannot even use an artificial * halt state. */ - return kvm_x86_ops.interrupt_allowed(vcpu); + return kvm_arch_interrupt_allowed(vcpu); } void kvm_arch_async_page_not_present(struct kvm_vcpu *vcpu, -- cgit v1.2.3