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authorSean Christopherson <seanjc@google.com>2021-12-21 10:37:00 -0500
committerPaolo Bonzini <pbonzini@redhat.com>2021-12-21 12:39:03 -0500
commitfdba608f15e2427419997b0898750a49a735afcb (patch)
treea85a6ebf72671cfa68f5f531e481690982013234 /arch/x86/kvm/vmx/vmx.c
parentab1ef34416a65ba11f66ae6435fcf0251cb46fd4 (diff)
downloadlinux-fdba608f15e2427419997b0898750a49a735afcb.tar.bz2
KVM: VMX: Wake vCPU when delivering posted IRQ even if vCPU == this vCPU
Drop a check that guards triggering a posted interrupt on the currently running vCPU, and more importantly guards waking the target vCPU if triggering a posted interrupt fails because the vCPU isn't IN_GUEST_MODE. If a vIRQ is delivered from asynchronous context, the target vCPU can be the currently running vCPU and can also be blocking, in which case skipping kvm_vcpu_wake_up() is effectively dropping what is supposed to be a wake event for the vCPU. The "do nothing" logic when "vcpu == running_vcpu" mostly works only because the majority of calls to ->deliver_posted_interrupt(), especially when using posted interrupts, come from synchronous KVM context. But if a device is exposed to the guest using vfio-pci passthrough, the VFIO IRQ and vCPU are bound to the same pCPU, and the IRQ is _not_ configured to use posted interrupts, wake events from the device will be delivered to KVM from IRQ context, e.g. vfio_msihandler() | |-> eventfd_signal() | |-> ... | |-> irqfd_wakeup() | |->kvm_arch_set_irq_inatomic() | |-> kvm_irq_delivery_to_apic_fast() | |-> kvm_apic_set_irq() This also aligns the non-nested and nested usage of triggering posted interrupts, and will allow for additional cleanups. Fixes: 379a3c8ee444 ("KVM: VMX: Optimize posted-interrupt delivery for timer fastpath") Cc: stable@vger.kernel.org Reported-by: Longpeng (Mike) <longpeng2@huawei.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> Message-Id: <20211208015236.1616697-18-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm/vmx/vmx.c')
-rw-r--r--arch/x86/kvm/vmx/vmx.c3
1 files changed, 1 insertions, 2 deletions
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 5974a88c9d35..0dbf94eb954f 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -3964,8 +3964,7 @@ static int vmx_deliver_posted_interrupt(struct kvm_vcpu *vcpu, int vector)
if (pi_test_and_set_on(&vmx->pi_desc))
return 0;
- if (vcpu != kvm_get_running_vcpu() &&
- !kvm_vcpu_trigger_posted_interrupt(vcpu, false))
+ if (!kvm_vcpu_trigger_posted_interrupt(vcpu, false))
kvm_vcpu_kick(vcpu);
return 0;