linux-kernel - Re: [PATCH 0/3] KVM: arm64: Normalize cache configuration

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Date:   Wed, 14 Dec 2022 00:59:17 +0000
From:   Oliver Upton <oliver.upton@...ux.dev>
To:     Akihiko Odaki <akihiko.odaki@...nix.com>
Cc:     Marc Zyngier <maz@...nel.org>, linux-kernel@...r.kernel.org,
        kvmarm@...ts.linux.dev, kvmarm@...ts.cs.columbia.edu,
        linux-arm-kernel@...ts.infradead.org,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        James Morse <james.morse@....com>,
        Will Deacon <will@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        asahi@...ts.linux.dev, Alyssa Rosenzweig <alyssa@...enzweig.io>,
        Sven Peter <sven@...npeter.dev>,
        Hector Martin <marcan@...can.st>
Subject: Re: [PATCH 0/3] KVM: arm64: Normalize cache configuration

Hi Akihiko,

On Sun, Dec 11, 2022 at 02:16:57PM +0900, Akihiko Odaki wrote:
> Before this change, the cache configuration of the physical CPU was
> exposed to vcpus. This is problematic because the cache configuration a
> vcpu sees varies when it migrates between vcpus with different cache
> configurations.
> 
> Fabricate cache configuration from arm64_ftr_reg_ctrel0.sys_val, which
> holds the CTR_EL0 value the userspace sees regardless of which physical
> CPU it resides on.
> 
> HCR_TID2 is now always set as it is troublesome to detect the difference
> of cache configurations among physical CPUs.
> 
> CSSELR_EL1 is now held in the memory instead of the corresponding
> phyisccal register as the fabricated cache configuration may have a
> cache level which does not exist in the physical CPU, and setting the
> physical CSSELR_EL1 for the level results in an UNKNOWN behavior.
> 
> CLIDR_EL1 and CCSIDR_EL1 are now writable from the userspace so that
> the VMM can restore the values saved with the old kernel.
> 
> Akihiko Odaki (3):
>   arm64/sysreg: Add CCSIDR2_EL1
>   arm64/cache: Move CLIDR macro definitions
>   KVM: arm64: Normalize cache configuration

Next time you do a respin can you please bump the version number? I.e.
the next version should be v3.

Additionally, it is tremendously helpful to reviewers if you can provide
(1) a summary of what has changed in the current revision and (2) a
lore.kernel.org link to the last series you mailed out.

--
Thanks,
Oliver