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KVM: arm64: Don't WARN on SMCCC filter reserved range allocation failure

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The first time userspace sets an SMCCC filter, kvm_smccc_set_filter()
inserts the reserved architecture ranges into the maple tree and WARNs
if that fails. The insertion allocates with GFP_KERNEL_ACCOUNT, so a
tight memory cgroup limit is enough for userspace to hit the WARN, even
though the -ENOMEM is also returned to it. The WARN dates back to when
the ranges were inserted at VM creation.

Leave -ENOMEM out of the WARN and keep it for every other error. The
two reserved ranges are fixed and disjoint and go into an empty tree
under config_lock, so any other error is a KVM bug.

Fixes: fb88707dd3 ("KVM: arm64: Use a maple tree to represent the SMCCC filter")
Reported-by: Sashiko <sashiko-bot@kernel.org>
Closes: https://lore.kernel.org/all/20260829055809.29AD31F000E9@smtp.kernel.org/
Suggested-by: Oliver Upton <oupton@kernel.org>
Signed-off-by: Fuad Tabba <fuad.tabba@linux.dev>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Reviewed-by: Oliver Upton <oupton@kernel.org>
Link: https://patch.msgid.link/20261013164334.1492070-1-fuad.tabba@linux.dev
Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Fuad Tabba 2026-10-13 17:43:34 +01:00 committed by Marc Zyngier
parent fd73f4a665
commit 09d5e94050
1 changed files with 3 additions and 1 deletions
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4
arch/arm64/kvm/hypercalls.c
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@ -197,8 +197,10 @@ static int kvm_smccc_set_filter(struct kvm *kvm, struct kvm_smccc_filter __user
if (!kvm_smccc_filter_configured(kvm)) {
r = kvm_smccc_filter_insert_reserved(kvm);
if (WARN_ON_ONCE(r))
if (r) {
WARN_ON_ONCE(r != -ENOMEM);
goto out_unlock;
}
}
r = mtree_insert_range(&kvm->arch.smccc_filter, start, end,