From: Marc Zyngier <maz@kernel.org>
To: Oliver Upton <oliver.upton@linux.dev>
Cc: kvmarm@lists.linux.dev, kvm@vger.kernel.org,
James Morse <james.morse@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Zenghui Yu <yuzenghui@huawei.com>
Subject: Re: [PATCH 5/8] KVM: arm64: Prevent NV feature flag on systems w/o nested virt
Date: Thu, 21 Sep 2023 09:25:13 +0100 [thread overview]
Message-ID: <87y1h02as6.wl-maz@kernel.org> (raw)
In-Reply-To: <20230920195036.1169791-6-oliver.upton@linux.dev>
On Wed, 20 Sep 2023 20:50:33 +0100,
Oliver Upton <oliver.upton@linux.dev> wrote:
>
> It would appear that userspace can select the NV feature flag regardless
> of whether the system actually supports the feature. Obviously a nested
> guest isn't getting far in this situation; let's reject the flag
> instead.
The current code is definitely odd. We rely on vcpu_has_nv() to return
false, meaning that we go all the way and initialise it as an EL1-only
guest. Duh. Well-behaved userspace would check the KVM_CAP_ARM_EL2
capability, which isn't upstream yet... :-(
Thanks for fixing this. I'll review the series as a whole.
M.
--
Without deviation from the norm, progress is not possible.
next prev parent reply other threads:[~2023-09-21 21:05 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-20 19:50 [PATCH 0/8] KVM: arm64: Cleanup + fix to vCPU reset, feature flags Oliver Upton
2023-09-20 19:50 ` [PATCH 1/8] KVM: arm64: Add generic check for system-supported vCPU features Oliver Upton
2023-09-21 8:30 ` Marc Zyngier
2023-09-21 12:47 ` Philippe Mathieu-Daudé
2023-09-20 19:50 ` [PATCH 2/8] KVM: arm64: Hoist PMUv3 check into KVM_ARM_VCPU_INIT ioctl handler Oliver Upton
2023-09-21 12:48 ` Philippe Mathieu-Daudé
2023-09-20 19:50 ` [PATCH 3/8] KVM: arm64: Hoist SVE " Oliver Upton
2023-09-20 19:50 ` [PATCH 4/8] KVM: arm64: Hoist PAuth checks into KVM_ARM_VCPU_INIT ioctl Oliver Upton
2023-09-20 19:50 ` [PATCH 5/8] KVM: arm64: Prevent NV feature flag on systems w/o nested virt Oliver Upton
2023-09-21 8:25 ` Marc Zyngier [this message]
2023-09-20 19:50 ` [PATCH 6/8] KVM: arm64: Hoist NV+SVE check into KVM_ARM_VCPU_INIT ioctl handler Oliver Upton
2023-09-20 19:50 ` [PATCH 7/8] KVM: arm64: Remove unused return value from kvm_reset_vcpu() Oliver Upton
2023-09-20 19:50 ` [PATCH 8/8] KVM: arm64: Get rid of vCPU-scoped feature bitmap Oliver Upton
2023-09-21 8:49 ` [PATCH 0/8] KVM: arm64: Cleanup + fix to vCPU reset, feature flags Marc Zyngier
2023-09-21 18:18 ` Oliver Upton
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