This is a note to let you know that I've just added the patch titled
KVM: x86: Ensure deadline timer has truly expired before posting its IRQ
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-x86-ensure-deadline-timer-has-truly-expired-before-posting-its-irq.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From beda430177f56656e7980dcce93456ffaa35676b Mon Sep 17 00:00:00 2001
From: Sean Christopherson <seanjc@xxxxxxxxxx>
Date: Thu, 4 Mar 2021 18:18:08 -0800
Subject: KVM: x86: Ensure deadline timer has truly expired before posting its IRQ
From: Sean Christopherson <seanjc@xxxxxxxxxx>
commit beda430177f56656e7980dcce93456ffaa35676b upstream.
When posting a deadline timer interrupt, open code the checks guarding
__kvm_wait_lapic_expire() in order to skip the lapic_timer_int_injected()
check in kvm_wait_lapic_expire(). The injection check will always fail
since the interrupt has not yet be injected. Moving the call after
injection would also be wrong as that wouldn't actually delay delivery
of the IRQ if it is indeed sent via posted interrupt.
Fixes: 010fd37fddf6 ("KVM: LAPIC: Reduce world switch latency caused by timer_advance_ns")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Message-Id: <20210305021808.3769732-1-seanjc@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kvm/lapic.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1641,7 +1641,16 @@ static void apic_timer_expired(struct kv
}
if (kvm_use_posted_timer_interrupt(apic->vcpu)) {
- kvm_wait_lapic_expire(vcpu);
+ /*
+ * Ensure the guest's timer has truly expired before posting an
+ * interrupt. Open code the relevant checks to avoid querying
+ * lapic_timer_int_injected(), which will be false since the
+ * interrupt isn't yet injected. Waiting until after injecting
+ * is not an option since that won't help a posted interrupt.
+ */
+ if (vcpu->arch.apic->lapic_timer.expired_tscdeadline &&
+ vcpu->arch.apic->lapic_timer.timer_advance_ns)
+ __kvm_wait_lapic_expire(vcpu);
kvm_apic_inject_pending_timer_irqs(apic);
return;
}
Patches currently in stable-queue which might be from seanjc@xxxxxxxxxx are
queue-5.10/kvm-x86-ensure-deadline-timer-has-truly-expired-before-posting-its-irq.patch
