diff options
| author | Marc Zyngier <maz@kernel.org> | 2023-01-12 15:38:27 +0300 |
|---|---|---|
| committer | Oliver Upton <oliver.upton@linux.dev> | 2023-01-26 21:48:47 +0300 |
| commit | 4d74ecfa6458bf482d93ad9a98c7f0423ff0564b (patch) | |
| tree | 2c0bea5a758896838bb9bf5454a1a7d18afeb06f /arch/arm64/kvm/arch_timer.c | |
| parent | b7bfaa761d760e72a969d116517eaa12e404c262 (diff) | |
| download | linux-4d74ecfa6458bf482d93ad9a98c7f0423ff0564b.tar.xz | |
KVM: arm64: Don't arm a hrtimer for an already pending timer
When fully emulating a timer, we back it with a hrtimer that is
armver on vcpu_load(). However, we do this even if the timer is
already pending.
This causes spurious interrupts to be taken, though the guest
doesn't observe them (the interrupt is already pending).
Although this is a waste of precious cycles, this isn't the
end of the world with the current state of KVM. However, this
can lead to a situation where a guest doesn't make forward
progress anymore with NV.
Fix it by checking that if the timer is already pending
before arming a new hrtimer. Also drop the hrtimer cancelling,
which is useless, by construction.
Reported-by: D Scott Phillips <scott@os.amperecomputing.com>
Fixes: bee038a67487 ("KVM: arm/arm64: Rework the timer code to use a timer_map")
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230112123829.458912-2-maz@kernel.org
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Diffstat (limited to 'arch/arm64/kvm/arch_timer.c')
| -rw-r--r-- | arch/arm64/kvm/arch_timer.c | 4 |
1 files changed, 1 insertions, 3 deletions
diff --git a/arch/arm64/kvm/arch_timer.c b/arch/arm64/kvm/arch_timer.c index bb24a76b4224..587d87aec33f 100644 --- a/arch/arm64/kvm/arch_timer.c +++ b/arch/arm64/kvm/arch_timer.c @@ -428,10 +428,8 @@ static void timer_emulate(struct arch_timer_context *ctx) * scheduled for the future. If the timer cannot fire at all, * then we also don't need a soft timer. */ - if (!kvm_timer_irq_can_fire(ctx)) { - soft_timer_cancel(&ctx->hrtimer); + if (should_fire || !kvm_timer_irq_can_fire(ctx)) return; - } soft_timer_start(&ctx->hrtimer, kvm_timer_compute_delta(ctx)); } |