From: Sean Christopherson <seanjc@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>, Joerg Roedel <joro@8bytes.org>
Cc: Sean Christopherson <seanjc@google.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>,
Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>,
kvm@vger.kernel.org, iommu@lists.linux-foundation.org,
linux-kernel@vger.kernel.org,
Maxim Levitsky <mlevitsk@redhat.com>
Subject: [PATCH v3 17/26] KVM: VMX: Wake vCPU when delivering posted IRQ even if vCPU == this vCPU
Date: Wed, 8 Dec 2021 01:52:27 +0000 [thread overview]
Message-ID: <20211208015236.1616697-18-seanjc@google.com> (raw)
In-Reply-To: <20211208015236.1616697-1-seanjc@google.com>
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.
The "do nothing" logic when "vcpu == running_vcpu" works only because KVM
doesn't have a path to ->deliver_posted_interrupt() from asynchronous
context, e.g. if apic_timer_expired() were changed to always go down the
posted interrupt path for APICv, or if the IN_GUEST_MODE check in
kvm_use_posted_timer_interrupt() were dropped, and the hrtimer fired in
kvm_vcpu_block() after the final kvm_vcpu_check_block() check, the vCPU
would be scheduled() out without being awakened, i.e. would "miss" the
timer interrupt.
One could argue that invoking kvm_apic_local_deliver() from (soft) IRQ
context for the current running vCPU should be illegal, but nothing in
KVM actually enforces that rules. There's also no strong obvious benefit
to making such behavior illegal, e.g. checking IN_GUEST_MODE and calling
kvm_vcpu_wake_up() is at worst marginally more costly than querying the
current running vCPU.
Lastly, this aligns the non-nested and nested usage of triggering posted
interrupts, and will allow for additional cleanups.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
---
arch/x86/kvm/vmx/vmx.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index fa90eacbf7e2..0eac98589472 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -3993,8 +3993,7 @@ static int vmx_deliver_posted_interrupt(struct kvm_vcpu *vcpu, int vector)
* guaranteed to see PID.ON=1 and sync the PIR to IRR if triggering a
* posted interrupt "fails" because vcpu->mode != IN_GUEST_MODE.
*/
- if (vcpu != kvm_get_running_vcpu() &&
- !kvm_vcpu_trigger_posted_interrupt(vcpu, false))
+ if (!kvm_vcpu_trigger_posted_interrupt(vcpu, false))
kvm_vcpu_wake_up(vcpu);
return 0;
--
2.34.1.400.ga245620fadb-goog
next prev parent reply other threads:[~2021-12-08 1:55 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-08 1:52 [PATCH v3 00/26] KVM: x86: Halt and APICv overhaul Sean Christopherson
2021-12-08 1:52 ` [PATCH v3 01/26] KVM: fix avic_set_running for preemptable kernels Sean Christopherson
2021-12-08 1:52 ` [PATCH v3 02/26] KVM: nVMX: Ensure vCPU honors event request if posting nested IRQ fails Sean Christopherson
2021-12-08 1:52 ` [PATCH v3 03/26] KVM: VMX: Clean up PI pre/post-block WARNs Sean Christopherson
2021-12-08 1:52 ` [PATCH v3 04/26] KVM: VMX: Handle PI wakeup shenanigans during vcpu_put/load Sean Christopherson
2021-12-08 1:52 ` [PATCH v3 05/26] KVM: Drop unused kvm_vcpu.pre_pcpu field Sean Christopherson
2021-12-08 1:52 ` [PATCH v3 06/26] KVM: Move x86 VMX's posted interrupt list_head to vcpu_vmx Sean Christopherson
2021-12-08 1:52 ` [PATCH v3 07/26] KVM: VMX: Move preemption timer <=> hrtimer dance to common x86 Sean Christopherson
2023-03-29 12:34 ` Tudor Ambarus
2023-03-29 13:47 ` Paolo Bonzini
2023-03-29 15:22 ` Tudor Ambarus
2023-03-30 7:12 ` Tudor Ambarus
2021-12-08 1:52 ` [PATCH v3 08/26] KVM: x86: Unexport LAPIC's switch_to_{hv,sw}_timer() helpers Sean Christopherson
2021-12-08 1:52 ` [PATCH v3 09/26] KVM: x86: Remove defunct pre_block/post_block kvm_x86_ops hooks Sean Christopherson
2021-12-08 1:52 ` [PATCH v3 10/26] KVM: SVM: Signal AVIC doorbell iff vCPU is in guest mode Sean Christopherson
2021-12-08 1:52 ` [PATCH v3 11/26] KVM: SVM: Don't bother checking for "running" AVIC when kicking for IPIs Sean Christopherson
2021-12-08 1:52 ` [PATCH v3 12/26] KVM: SVM: Remove unnecessary APICv/AVIC update in vCPU unblocking path Sean Christopherson
2021-12-08 1:52 ` [PATCH v3 13/26] KVM: SVM: Use kvm_vcpu_is_blocking() in AVIC load to handle preemption Sean Christopherson
2021-12-08 1:52 ` [PATCH v3 14/26] KVM: SVM: Skip AVIC and IRTE updates when loading blocking vCPU Sean Christopherson
2021-12-08 1:52 ` [PATCH v3 15/26] iommu/amd: KVM: SVM: Use pCPU to infer IsRun state for IRTE Sean Christopherson
2021-12-08 1:52 ` [PATCH v3 16/26] KVM: VMX: Don't do full kick when triggering posted interrupt "fails" Sean Christopherson
2021-12-08 1:52 ` Sean Christopherson [this message]
2021-12-08 1:52 ` [PATCH v3 18/26] KVM: VMX: Pass desired vector instead of bool for triggering posted IRQ Sean Christopherson
2021-12-08 1:52 ` [PATCH v3 19/26] KVM: VMX: Fold fallback path into triggering posted IRQ helper Sean Christopherson
2021-12-08 1:52 ` [PATCH v3 20/26] KVM: VMX: Don't do full kick when handling posted interrupt wakeup Sean Christopherson
2021-12-08 1:52 ` [PATCH v3 21/26] KVM: SVM: Drop AVIC's intermediate avic_set_running() helper Sean Christopherson
2021-12-08 14:43 ` Paolo Bonzini
2021-12-08 15:03 ` Maxim Levitsky
2021-12-08 15:43 ` Sean Christopherson
2021-12-08 1:52 ` [PATCH v3 22/26] KVM: SVM: Move svm_hardware_setup() and its helpers below svm_x86_ops Sean Christopherson
2021-12-08 1:52 ` [PATCH v3 23/26] KVM: SVM: Nullify vcpu_(un)blocking() hooks if AVIC is disabled Sean Christopherson
2021-12-08 1:52 ` [PATCH v3 24/26] KVM: x86: Skip APICv update if APICv is disable at the module level Sean Christopherson
2021-12-08 1:52 ` [PATCH v3 25/26] KVM: x86: Drop NULL check on kvm_x86_ops.check_apicv_inhibit_reasons Sean Christopherson
2021-12-08 1:52 ` [PATCH v3 26/26] KVM: x86: Unexport __kvm_request_apicv_update() Sean Christopherson
2021-12-08 9:04 ` [PATCH v3 00/26] KVM: x86: Halt and APICv overhaul Paolo Bonzini
2021-12-08 14:51 ` Paolo Bonzini
2021-12-08 23:00 ` Maxim Levitsky
2021-12-08 23:16 ` Maxim Levitsky
2021-12-08 23:34 ` Maxim Levitsky
2021-12-09 0:04 ` Sean Christopherson
2021-12-09 6:36 ` Maxim Levitsky
2021-12-09 0:02 ` Sean Christopherson
2021-12-09 14:29 ` Paolo Bonzini
2021-12-09 14:48 ` Maxim Levitsky
2021-12-09 15:45 ` Sean Christopherson
2021-12-09 16:03 ` Maxim Levitsky
2021-12-09 1:37 ` Sean Christopherson
2021-12-09 6:31 ` Maxim Levitsky
2021-12-08 23:43 ` Sean Christopherson
2021-12-09 6:34 ` Maxim Levitsky
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