From: Steffen Eiden <seiden@linux.ibm.com>
To: Karl Mehltretter <kmehltretter@gmail.com>
Cc: Marc Zyngier <maz@kernel.org>, Oliver Upton <oupton@kernel.org>,
kvmarm@lists.linux.dev, Fuad Tabba <fuad.tabba@linux.dev>,
Joey Gouly <joey.gouly@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Zenghui Yu <yuzenghui@huawei.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Sean Christopherson <seanjc@google.com>,
Shuah Khan <shuah@kernel.org>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
linux-kselftest@vger.kernel.org
Subject: Re: [PATCH 1/2] KVM: arm64: Return -EINVAL for an empty SMCCC filter range at base 0
Date: Tue, 1 Sep 2026 09:38:59 +0200 [thread overview]
Message-ID: <20260901073859.185345-A-seiden@linux.ibm.com> (raw)
In-Reply-To: <20260829054856.70549-2-kmehltretter@gmail.com>
On Sat, Aug 29, 2026 at 07:48:55AM +0200, Karl Mehltretter wrote:
> kvm_smccc_set_filter() only rejects a range if its inclusive end,
> base + nr_functions - 1, is below base. That catches an empty range
> (nr_functions == 0) at every nonzero base, but at base 0 the end wraps
> to U32_MAX and KVM tries to insert [0, U32_MAX], which overlaps the
> reserved Arm Architecture Calls ranges. KVM_ARM_VM_SMCCC_FILTER then
> returns -EEXIST instead of the -EINVAL that the smccc_filter selftest
> expects for an empty range.
>
> Reject a zero function count explicitly.
>
> Tested with a userspace reproducer on an arm64 VHE host under QEMU TCG:
> EEXIST before, EINVAL after.
>
> Fixes: 821d935c87bc ("KVM: arm64: Introduce support for userspace SMCCC filtering")
> Assisted-by: LLM
> Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com>
Good catch.
Reviewed-by: Steffen Eiden <seiden@linux.ibm.com>
FWIW: Tested it on my downstream version of arm-on-s390 with hypercalls
already implemented.
next prev parent reply other threads:[~2026-09-01 7:39 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-29 5:48 [PATCH 0/2] KVM: arm64: Return -EINVAL for an empty SMCCC filter range at base 0 Karl Mehltretter
2026-08-29 5:48 ` [PATCH 1/2] " Karl Mehltretter
2026-08-29 5:58 ` sashiko-bot
2026-08-29 15:04 ` Fuad Tabba
2026-08-29 15:53 ` Karl Mehltretter
2026-08-29 15:55 ` Fuad Tabba
2026-09-01 7:38 ` Steffen Eiden [this message]
2026-08-29 5:48 ` [PATCH 2/2] KVM: arm64: selftests: Test " Karl Mehltretter
2026-08-29 15:04 ` Fuad Tabba
2026-09-01 7:39 ` Steffen Eiden
2026-09-15 22:25 ` [PATCH 0/2] KVM: arm64: Return -EINVAL for an " Oliver Upton
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