linux-kernel - Re: [PATCH v2 0/4] KVM: arm64: Fix underallocation of storage for SVE state

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Message-ID: <Zoavx64l_slLUvfR@arm.com>
Date: Thu, 4 Jul 2024 15:20:55 +0100
From: Catalin Marinas <catalin.marinas@....com>
To: Mark Brown <broonie@...nel.org>
Cc: Will Deacon <will@...nel.org>, Marc Zyngier <maz@...nel.org>,
	Oliver Upton <oliver.upton@...ux.dev>,
	James Morse <james.morse@....com>,
	Suzuki K Poulose <suzuki.poulose@....com>,
	Fuad Tabba <tabba@...gle.com>, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org, kvmarm@...ts.linux.dev
Subject: Re: [PATCH v2 0/4] KVM: arm64: Fix underallocation of storage for
 SVE state

On Thu, Jun 06, 2024 at 04:21:42PM +0100, Mark Brown wrote:
> As observed during review the pKVM support for saving host SVE state is
> broken if an asymmetric system has VLs larger than the maximum shared
> VL, fix this by discovering then using the maximum VL for allocations
> and using RDVL during the save/restore process.
> 
> Signed-off-by: Mark Brown <broonie@...nel.org>
> ---
> Changes in v2:
> - Downgrade check for a late CPU increasing maximum VL to a warning only
>   but do it unconditionally since pKVM prevents late CPUs anyway.
> - Commit log tweaks.
> - Link to v1: https://lore.kernel.org/r/20240605-kvm-arm64-fix-pkvm-sve-vl-v1-0-680d6b43b4c1@kernel.org
> 
> ---
> Mark Brown (4):
>       arm64/fpsimd: Introduce __bit_to_vl() helper
>       arm64/fpsimd: Discover maximum vector length implemented by any CPU
>       KVM: arm64: Fix FFR offset calculation for pKVM host state save and restore
>       KVM: arm64: Avoid underallocating storage for host SVE state

Since the patches address a KVM issue, I think it should go via
Oliver/Marc's tree. But happy to queue it via the arm64 tree if people
think otherwise.

Thanks.

-- 
Catalin