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Date: Thu, 31 Oct 2024 11:49:38 +0000
From: Catalin Marinas <catalin.marinas@arm.com>
To: Joey Gouly <joey.gouly@arm.com>
Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev,
	anshuman.khandual@arm.com, gshan@redhat.com, james.morse@arm.com,
	shameerali.kolothum.thodi@huawei.com, Marc Zyngier <maz@kernel.org>,
	Oliver Upton <oliver.upton@linux.dev>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Zenghui Yu <yuzenghui@huawei.com>,
	Jing Zhang <jingzhangos@google.com>, Will Deacon <will@kernel.org>
Subject: Re: [PATCH v6 2/7] arm64: head.S: Initialise MPAM EL2 registers and
 disable traps
Message-ID: <ZyNu0mDR0aicfPrS@arm.com>
References: <20241030160317.2528209-1-joey.gouly@arm.com>
 <20241030160317.2528209-3-joey.gouly@arm.com>
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In-Reply-To: <20241030160317.2528209-3-joey.gouly@arm.com>

On Wed, Oct 30, 2024 at 04:03:12PM +0000, Joey Gouly wrote:
> From: James Morse <james.morse@arm.com>
> 
> Add code to head.S's el2_setup to detect MPAM and disable any EL2 traps.
> This register resets to an unknown value, setting it to the default
> parititons/pmg before we enable the MMU is the best thing to do.
> 
> Kexec/kdump will depend on this if the previous kernel left the CPU
> configured with a restrictive configuration.
> 
> If linux is booted at the highest implemented exception level el2_setup
> will clear the enable bit, disabling MPAM.
> 
> This code can't be enabled until a subsequent patch adds the Kconfig
> and cpufeature boiler plate.
> 
> Signed-off-by: James Morse <james.morse@arm.com>
> Signed-off-by: Joey Gouly <joey.gouly@arm.com>
> Reviewed-by: Gavin Shan <gshan@redhat.com>
> Tested-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>

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