diff options
| author | Sean Christopherson <seanjc@google.com> | 2021-12-08 04:52:14 +0300 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2022-01-19 20:14:37 +0300 |
| commit | d76fb40637fc0e84b27bf431cd72cf8fe3f813ef (patch) | |
| tree | 28d138efd4da8a43124e363f5302eb7903d25fcc /arch/x86/kvm/vmx/vmx.c | |
| parent | 4f5a884fc212d99654e4fb36ba98d5354f0dd18e (diff) | |
| download | linux-d76fb40637fc0e84b27bf431cd72cf8fe3f813ef.tar.xz | |
KVM: VMX: Handle PI descriptor updates during vcpu_put/load
Move the posted interrupt pre/post_block logic into vcpu_put/load
respectively, using the kvm_vcpu_is_blocking() to determining whether or
not the wakeup handler needs to be set (and unset). This avoids updating
the PI descriptor if halt-polling is successful, reduces the number of
touchpoints for updating the descriptor, and eliminates the confusing
behavior of intentionally leaving a "stale" PI.NDST when a blocking vCPU
is scheduled back in after preemption.
The downside is that KVM will do the PID update twice if the vCPU is
preempted after prepare_to_rcuwait() but before schedule(), but that's a
rare case (and non-existent on !PREEMPT kernels).
The notable wart is the need to send a self-IPI on the wakeup vector if
an outstanding notification is pending after configuring the wakeup
vector. Ideally, KVM would just do a kvm_vcpu_wake_up() in this case,
but the scheduler doesn't support waking a task from its preemption
notifier callback, i.e. while the task is right in the middle of
being scheduled out.
Note, setting the wakeup vector before halt-polling is not necessary:
once the pending IRQ will be recorded in the PIR, kvm_vcpu_has_events()
will detect this (via kvm_cpu_get_interrupt(), kvm_apic_get_interrupt(),
apic_has_interrupt_for_ppr() and finally vmx_sync_pir_to_irr()) and
terminate the polling.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20211208015236.1616697-5-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.c | 5 |
1 files changed, 0 insertions, 5 deletions
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 41aaa37d9eb8..3a9a49a87b9d 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -7566,9 +7566,6 @@ void vmx_update_cpu_dirty_logging(struct kvm_vcpu *vcpu) static int vmx_pre_block(struct kvm_vcpu *vcpu) { - if (pi_pre_block(vcpu)) - return 1; - if (kvm_lapic_hv_timer_in_use(vcpu)) kvm_lapic_switch_to_sw_timer(vcpu); @@ -7579,8 +7576,6 @@ static void vmx_post_block(struct kvm_vcpu *vcpu) { if (kvm_x86_ops.set_hv_timer) kvm_lapic_switch_to_hv_timer(vcpu); - - pi_post_block(vcpu); } static void vmx_setup_mce(struct kvm_vcpu *vcpu) |