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From: Oliver Upton <oliver.upton@linux.dev>
To: Marc Zyngier <maz@kernel.org>
Cc: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org,
	Joey Gouly <joey.gouly@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Zenghui Yu <yuzenghui@huawei.com>
Subject: Re: [PATCH] KVM: arm64: nv: Hold mmu_lock when invalidating VNCR SW-TLB before translating
Date: Tue, 20 May 2025 07:44:49 -0700	[thread overview]
Message-ID: <aCyVYfg3Fy3Nzluh@linux.dev> (raw)
In-Reply-To: <20250520144116.3667978-1-maz@kernel.org>

On Tue, May 20, 2025 at 03:41:16PM +0100, Marc Zyngier wrote:
> When translating a VNCR translation fault, we start by marking the
> current SW-managed TLB as invalid, so that we can populate it
> in place. This is, however, done without the mmu_lock held.
> 
> A consequence of this is that another CPU dealing with TLBI
> emulation can observe a translation still flagged as valid, but
> with invalid walk results (such as pgshift being 0). Bad things
> can result from this, such as a BUG() in pgshift_level_to_ttl().
> 
> Fix it by taking the mmu_lock for write to perform this local
> invalidation, and use invalidate_vncr() instead of open-coding
> the write to the 'valid' flag.
> 
> Fixes: 069a05e535496 ("KVM: arm64: nv: Handle VNCR_EL2-triggered faults")
> Signed-off-by: Marc Zyngier <maz@kernel.org>

Reviewed-by: Oliver Upton <oliver.upton@linux.dev>

Thanks,
Oliver


  reply	other threads:[~2025-05-20 14:48 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-05-20 14:41 [PATCH] KVM: arm64: nv: Hold mmu_lock when invalidating VNCR SW-TLB before translating Marc Zyngier
2025-05-20 14:44 ` Oliver Upton [this message]
2025-05-21  9:09 ` Marc Zyngier

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