From: Peter Xu peterx@redhat.com
commit 654f1f13ea56b92bacade8ce2725aea0457f91c0 upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/x86/kvm/irq.c | 7 +++++++ arch/x86/kvm/irq.h | 1 + virt/kvm/eventfd.c | 9 +++++++++ 3 files changed, 17 insertions(+)
--- a/arch/x86/kvm/irq.c +++ b/arch/x86/kvm/irq.c @@ -172,3 +172,10 @@ void __kvm_migrate_timers(struct kvm_vcp __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); +} --- a/arch/x86/kvm/irq.h +++ b/arch/x86/kvm/irq.h @@ -114,6 +114,7 @@ static inline int irqchip_in_kernel(stru 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); --- a/virt/kvm/eventfd.c +++ b/virt/kvm/eventfd.c @@ -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 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;