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Date: Thu, 4 Jun 2026 17:50:15 +0100
From: Catalin Marinas <catalin.marinas@arm.com>
To: Ard Biesheuvel <ardb+git@google.com>
Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
	will@kernel.org, Ard Biesheuvel <ardb@kernel.org>,
	Kevin Brodsky <kevin.brodsky@arm.com>,
	Mark Brown <broonie@kernel.org>, Marc Zyngier <maz@kernel.org>,
	stable@vger.kernel.org
Subject: Re: [PATCH v2 4/5] KVM: arm64: Omit tag sync on stage-2 mappings of
 the zero page
Message-ID: <aiGsx2Ls676t7-iJ@arm.com>
References: <20260604151151.150377-7-ardb+git@google.com>
 <20260604151151.150377-11-ardb+git@google.com>
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In-Reply-To: <20260604151151.150377-11-ardb+git@google.com>

On Thu, Jun 04, 2026 at 05:11:56PM +0200, Ard Biesheuvel wrote:
> From: Ard Biesheuvel <ardb@kernel.org>
> 
> Commit
> 
>    f620d66af316 ("arm64: mte: Do not flag the zero page as PG_mte_tagged")
> 
> removed the PG_mte_tagged flag from the zero page, but missed a KVM code
> path that may set this flag on the zero page when it is used in a
> stage-2 CoW mapping of anonymous memory.
> 
> So disregard the zero page explicitly in sanitise_mte_tags().
> 
> Fixes: f620d66af316 ("arm64: mte: Do not flag the zero page as PG_mte_tagged")
> Cc: <stable@vger.kernel.org> # 5.10.x
> Suggested-by: Catalin Marinas <catalin.marinas@arm.com>
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>