linux-kernel - Re: [PATCH v4 07/21] arm64/sme: Enable host kernel to access ZT0

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Message-ID: <Y+EuVbkpQJk6z+Zu@arm.com>
Date:   Mon, 6 Feb 2023 16:44:05 +0000
From:   Catalin Marinas <catalin.marinas@....com>
To:     Marc Zyngier <maz@...nel.org>
Cc:     Mark Brown <broonie@...nel.org>, Will Deacon <will@...nel.org>,
        Oleg Nesterov <oleg@...hat.com>,
        James Morse <james.morse@....com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Oliver Upton <oliver.upton@...ux.dev>,
        Shuah Khan <shuah@...nel.org>,
        Alan Hayward <alan.hayward@....com>,
        Luis Machado <luis.machado@....com>,
        Szabolcs Nagy <szabolcs.nagy@....com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kvmarm@...ts.linux.dev, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH v4 07/21] arm64/sme: Enable host kernel to access ZT0

On Mon, Feb 06, 2023 at 09:31:20AM +0000, Marc Zyngier wrote:
> From a6c4aaccd33e453ffc8d8ea23a4dd4d9a263cc89 Mon Sep 17 00:00:00 2001
> From: Marc Zyngier <maz@...nel.org>
> Date: Mon, 6 Feb 2023 09:24:40 +0000
> Subject: [PATCH] arm64/sme: Fix __finalise_el2 SMEver check
> 
> When checking for ID_AA64SMFR0_EL1.SMEver, __check_override assumes
> that the ID_AA64SMFR0_EL1 value is in x1, and the intent of the code
> is to reuse value read a few lines above.
> 
> However, as the comment says at the beginning of the macro, x1 will
> be clobbered, and the checks always fails.
> 
> The easiest fix is just to reload the id register before checking it.
> 
> Fixes: f122576f3533 ("arm64/sme: Enable host kernel to access ZT0")
> Signed-off-by: Marc Zyngier <maz@...nel.org>

Thanks Marc. I queued it on top of the for-next/sme2 branch.

-- 
Catalin