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Reply-To: Sean Christopherson <seanjc@google.com>
Date: Tue, 1 Apr 2025 08:47:26 -0700
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Message-ID: <20250401154727.835231-2-seanjc@google.com>
Subject: [PATCH 1/2] KVM: VMX: Assert that IRQs are disabled when putting vCPU
on PI wakeup list
From: Sean Christopherson <seanjc@google.com>
To: Sean Christopherson <seanjc@google.com>,
Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Yan Zhao <yan.y.zhao@intel.com>
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Assert that IRQs are already disabled when putting a vCPU on a CPU's PI
wakeup list, as opposed to saving/disabling+restoring IRQs. KVM relies on
IRQs being disabled until the vCPU task is fully scheduled out, i.e. until
the scheduler has dropped all of its per-CPU locks (e.g. for the runqueue),
as attempting to wake the task while it's being scheduled out could lead
to deadlock.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Yan Zhao <yan.y.zhao@intel.com>
---
arch/x86/kvm/vmx/posted_intr.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)
diff --git a/arch/x86/kvm/vmx/posted_intr.c b/arch/x86/kvm/vmx/posted_intr.c
index ec08fa3caf43..840d435229a8 100644
--- a/arch/x86/kvm/vmx/posted_intr.c
+++ b/arch/x86/kvm/vmx/posted_intr.c
@@ -148,9 +148,8 @@ static void pi_enable_wakeup_handler(struct kvm_vcpu *v=
cpu)
struct pi_desc *pi_desc =3D vcpu_to_pi_desc(vcpu);
struct vcpu_vmx *vmx =3D to_vmx(vcpu);
struct pi_desc old, new;
- unsigned long flags;
=20
- local_irq_save(flags);
+ lockdep_assert_irqs_disabled();
=20
raw_spin_lock(&per_cpu(wakeup_vcpus_on_cpu_lock, vcpu->cpu));
list_add_tail(&vmx->pi_wakeup_list,
@@ -176,8 +175,6 @@ static void pi_enable_wakeup_handler(struct kvm_vcpu *v=
cpu)
*/
if (pi_test_on(&new))
__apic_send_IPI_self(POSTED_INTR_WAKEUP_VECTOR);
-
- local_irq_restore(flags);
}
=20
static bool vmx_needs_pi_wakeup(struct kvm_vcpu *vcpu)
--=20
2.49.0.472.ge94155a9ec-goog