kvm: Check irqchip mode before assign irqfd (654f1f13) · Commits · 戴 / test

When assigning kvm irqfd we didn't check the irqchip mode but we allow KVM_IRQFD to succeed with all the irqchip modes. However it does not make much sense to create irqfd even without the kernel chips. Let's provide a arch-dependent helper to check whether a specific irqfd is allowed by the arch. At least for x86, it should make sense to check: - when irqchip mode is NONE, all irqfds should be disallowed, and, - when irqchip mode is SPLIT, irqfds that are with resamplefd should be disallowed. For either of the case, previously we'll silently ignore the irq or the irq ack event if the irqchip mode is incorrect. However that can cause misterious guest behaviors and it can be hard to triage. Let's fail KVM_IRQFD even earlier to detect these incorrect configurations. CC: Paolo Bonzini <pbonzini@redhat.com> CC: Radim Krčmář <rkrcmar@redhat.com> CC: Alex Williamson <alex.williamson@redhat.com> CC: Eduardo Habkost <ehabkost@redhat.com> Signed-off-by:

Peter Xu <peterx@redhat.com> Cc: stable@vger.kernel.org Signed-off-by:

Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/irq.c

+7 −0

Original line number	Diff line number	Diff line
		@@ -172,3 +172,10 @@ void __kvm_migrate_timers(struct kvm_vcpu *vcpu)
		__kvm_migrate_apic_timer(vcpu);
		__kvm_migrate_pit_timer(vcpu);
		}

		bool kvm_arch_irqfd_allowed(struct kvm kvm, struct kvm_irqfd args)
		{
		bool resample = args->flags & KVM_IRQFD_FLAG_RESAMPLE;

		return resample ? irqchip_kernel(kvm) : irqchip_in_kernel(kvm);
		}

arch/x86/kvm/irq.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -114,6 +114,7 @@ static inline int irqchip_in_kernel(struct kvm *kvm)
		return mode != KVM_IRQCHIP_NONE;
		}

		bool kvm_arch_irqfd_allowed(struct kvm kvm, struct kvm_irqfd args);
		void kvm_inject_pending_timer_irqs(struct kvm_vcpu *vcpu);
		void kvm_inject_apic_timer_irqs(struct kvm_vcpu *vcpu);
		void kvm_apic_nmi_wd_deliver(struct kvm_vcpu *vcpu);

virt/kvm/eventfd.c

+9 −0

Original line number	Diff line number	Diff line
		@@ -44,6 +44,12 @@

		static struct workqueue_struct *irqfd_cleanup_wq;

		bool __attribute__((weak))
		kvm_arch_irqfd_allowed(struct kvm kvm, struct kvm_irqfd args)
		{
		return true;
		}

		static void
		irqfd_inject(struct work_struct *work)
		{
		@@ -297,6 +303,9 @@ kvm_irqfd_assign(struct kvm kvm, struct kvm_irqfd args)
		if (!kvm_arch_intc_initialized(kvm))
		return -EAGAIN;

		if (!kvm_arch_irqfd_allowed(kvm, args))
		return -EINVAL;

		irqfd = kzalloc(sizeof(*irqfd), GFP_KERNEL_ACCOUNT);
		if (!irqfd)
		return -ENOMEM;

Admin message