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KVM: arm64: vgic-its: Add error handling in vgic_its_cache_translation

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The return value of xa_store() needs to be checked. This fix adds an
error handling path that resolves the kref inconsistency on failure. As
suggested by Oliver Upton, this function does not return the error code
intentionally because the translation cache is best effort.

Fixes: 8201d1028c ("KVM: arm64: vgic-its: Maintain a translation cache per ITS")
Signed-off-by: Keisuke Nishimura <keisuke.nishimura@inria.fr>
Suggested-by: Oliver Upton <oliver.upton@linux.dev>
Acked-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20241130144952.23729-1-keisuke.nishimura@inria.fr
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
This commit is contained in:
Keisuke Nishimura 2024-11-30 15:49:53 +01:00 committed by Oliver Upton
parent 03c7527e97
commit be7e611274
1 changed files with 11 additions and 1 deletions
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12
arch/arm64/kvm/vgic/vgic-its.c
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@ -608,12 +608,22 @@ static void vgic_its_cache_translation(struct kvm *kvm, struct vgic_its *its,
lockdep_assert_held(&its->its_lock);
vgic_get_irq_kref(irq);
old = xa_store(&its->translation_cache, cache_key, irq, GFP_KERNEL_ACCOUNT);
/*
* Put the reference taken on @irq if the store fails. Intentionally do
* not return the error as the translation cache is best effort.
*/
if (xa_is_err(old)) {
vgic_put_irq(kvm, irq);
return;
}
/*
* We could have raced with another CPU caching the same
* translation behind our back, ensure we don't leak a
* reference if that is the case.
*/
old = xa_store(&its->translation_cache, cache_key, irq, GFP_KERNEL_ACCOUNT);
if (old)
vgic_put_irq(kvm, old);
}