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| author | Marcelo Tosatti <mtosatti@redhat.com> | 2021-05-26 20:20:14 +0300 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2021-05-27 14:58:23 +0300 |
| commit | a2486020a82eefad686993695eb42d1b64f3f2fd (patch) | |
| tree | 70042d25ee1000fe5105acacd2a282b22c203326 /arch/x86/kvm/vmx/posted_intr.h | |
| parent | 084071d5e9226add45a6031928bf10e6afc855fd (diff) | |
| download | linux-a2486020a82eefad686993695eb42d1b64f3f2fd.tar.xz | |
KVM: VMX: update vcpu posted-interrupt descriptor when assigning device
For VMX, when a vcpu enters HLT emulation, pi_post_block will:
1) Add vcpu to per-cpu list of blocked vcpus.
2) Program the posted-interrupt descriptor "notification vector"
to POSTED_INTR_WAKEUP_VECTOR
With interrupt remapping, an interrupt will set the PIR bit for the
vector programmed for the device on the CPU, test-and-set the
ON bit on the posted interrupt descriptor, and if the ON bit is clear
generate an interrupt for the notification vector.
This way, the target CPU wakes upon a device interrupt and wakes up
the target vcpu.
Problem is that pi_post_block only programs the notification vector
if kvm_arch_has_assigned_device() is true. Its possible for the
following to happen:
1) vcpu V HLTs on pcpu P, kvm_arch_has_assigned_device is false,
notification vector is not programmed
2) device is assigned to VM
3) device interrupts vcpu V, sets ON bit
(notification vector not programmed, so pcpu P remains in idle)
4) vcpu 0 IPIs vcpu V (in guest), but since pi descriptor ON bit is set,
kvm_vcpu_kick is skipped
5) vcpu 0 busy spins on vcpu V's response for several seconds, until
RCU watchdog NMIs all vCPUs.
To fix this, use the start_assignment kvm_x86_ops callback to kick
vcpus out of the halt loop, so the notification vector is
properly reprogrammed to the wakeup vector.
Reported-by: Pei Zhang <pezhang@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Message-Id: <20210526172014.GA29007@fuller.cnet>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm/vmx/posted_intr.h')
| -rw-r--r-- | arch/x86/kvm/vmx/posted_intr.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/kvm/vmx/posted_intr.h b/arch/x86/kvm/vmx/posted_intr.h index 0bdc41391c5b..7f7b2326caf5 100644 --- a/arch/x86/kvm/vmx/posted_intr.h +++ b/arch/x86/kvm/vmx/posted_intr.h @@ -95,5 +95,6 @@ void __init pi_init_cpu(int cpu); bool pi_has_pending_interrupt(struct kvm_vcpu *vcpu); int pi_update_irte(struct kvm *kvm, unsigned int host_irq, uint32_t guest_irq, bool set); +void vmx_pi_start_assignment(struct kvm *kvm); #endif /* __KVM_X86_VMX_POSTED_INTR_H */ |