linux-kernel - Re: [PATCH v2 01/11] KVM: arm64: initialize HCRX

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Message-ID: <87wn0lndn4.wl-maz@kernel.org>
Date:   Sat, 03 Jun 2023 09:39:11 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     Kristina Martsenko <kristina.martsenko@....com>
Cc:     linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Oliver Upton <oliver.upton@...ux.dev>,
        James Morse <james.morse@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Zenghui Yu <yuzenghui@...wei.com>,
        Mark Rutland <mark.rutland@....com>,
        Mark Brown <broonie@...nel.org>,
        Luis Machado <luis.machado@....com>,
        Vladimir Murzin <vladimir.murzin@....com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 01/11] KVM: arm64: initialize HCRX_EL2

On Tue, 09 May 2023 15:22:25 +0100,
Kristina Martsenko <kristina.martsenko@....com> wrote:
> 
> ARMv8.7/9.2 adds a new hypervisor configuration register HCRX_EL2.
> Initialize the register to a safe value (all fields 0), to be robust
> against firmware that has not initialized it. This is also needed to
> ensure that the register is reinitialized after a kexec by a future
> kernel.
> 
> In addition, move SMPME setup over to the new flags, as it would
> otherwise get overridden. It is safe to set the bit even if SME is not
> (uniformly) supported, as it will write to a RES0 bit (having no
> effect), and SME will be disabled by the cpufeature framework.
> (Similar to how e.g. the API bit is handled in HCR_HOST_NVHE_FLAGS.)
> 
> Signed-off-by: Kristina Martsenko <kristina.martsenko@....com>

Acked-by: Marc Zyngier <maz@...nel.org>

	M.

-- 
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