From: Marc Zyngier <maz@kernel.org>
To: Steven Price <steven.price@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>, James Morse <james.morse@arm.com>,
Julien Thierry <julien.thierry.kdev@gmail.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, Dave Martin <Dave.Martin@arm.com>
Subject: Re: [PATCH] KVM: arm64: kvm_reset_vcpu() return code incorrect with SVE
Date: Wed, 17 Jun 2020 11:47:41 +0100 [thread overview]
Message-ID: <c9761495762abe174e6546122916fc38@kernel.org> (raw)
In-Reply-To: <20200617104339.35094-1-steven.price@arm.com>
Hi Steven,
On 2020-06-17 11:43, Steven Price wrote:
> If SVE is enabled then 'ret' can be assigned the return value of
> kvm_vcpu_enable_sve() which may be 0 causing future "goto out" sites to
> erroneously return 0 on failure rather than -EINVAL as expected.
>
> Remove the initialisation of 'ret' and make setting the return value
> explicit to avoid this situation in the future.
>
> Fixes: 9a3cdf26e336 ("KVM: arm64/sve: Allow userspace to enable SVE for
> vcpus")
> Reported-by: James Morse <james.morse@arm.com>
> Signed-off-by: Steven Price <steven.price@arm.com>
> ---
> The problematic chunk isn't visible in the diff, so reproduced here:
>
> if (!kvm_arm_vcpu_sve_finalized(vcpu)) {
> if (test_bit(KVM_ARM_VCPU_SVE, vcpu->arch.features)) {
> ret = kvm_vcpu_enable_sve(vcpu);
> if (ret)
> goto out;
> }
> } else {
> kvm_vcpu_reset_sve(vcpu);
> }
>
> arch/arm64/kvm/reset.c | 10 +++++++---
> 1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
> index d3b209023727..f1057603b756 100644
> --- a/arch/arm64/kvm/reset.c
> +++ b/arch/arm64/kvm/reset.c
> @@ -245,7 +245,7 @@ static int kvm_vcpu_enable_ptrauth(struct kvm_vcpu
> *vcpu)
> */
> int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
> {
> - int ret = -EINVAL;
> + int ret;
> bool loaded;
> u32 pstate;
>
> @@ -269,15 +269,19 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
>
> if (test_bit(KVM_ARM_VCPU_PTRAUTH_ADDRESS, vcpu->arch.features) ||
> test_bit(KVM_ARM_VCPU_PTRAUTH_GENERIC, vcpu->arch.features)) {
> - if (kvm_vcpu_enable_ptrauth(vcpu))
> + if (kvm_vcpu_enable_ptrauth(vcpu)) {
> + ret = -EINVAL;
> goto out;
> + }
> }
>
> switch (vcpu->arch.target) {
> default:
> if (test_bit(KVM_ARM_VCPU_EL1_32BIT, vcpu->arch.features)) {
> - if (!cpus_have_const_cap(ARM64_HAS_32BIT_EL1))
> + if (cpus_have_const_cap(ARM64_HAS_32BIT_EL1)) {
Do you really mean this? Seems counter-productive... :-(
> + ret = -EINVAL;
> goto out;
> + }
> pstate = VCPU_RESET_PSTATE_SVC;
> } else {
> pstate = VCPU_RESET_PSTATE_EL1;
Thanks,
M.
--
Jazz is not dead. It just smells funny...
next prev parent reply other threads:[~2020-06-17 10:47 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-17 10:43 [PATCH] KVM: arm64: kvm_reset_vcpu() return code incorrect with SVE Steven Price
2020-06-17 10:47 ` Marc Zyngier [this message]
2020-06-17 10:50 ` Steven Price
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