linux-kernel - Re: [PATCH v2] KVM: arm64: Constrain the host to the maximum shared SVE VL with pKVM

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Message-Id: <172779288243.1647258.11526223607121965745.b4-ty@kernel.org>
Date: Tue,  1 Oct 2024 15:28:40 +0100
From: Marc Zyngier <maz@...nel.org>
To: Oliver Upton <oliver.upton@...ux.dev>,
	James Morse <james.morse@....com>,
	Suzuki K Poulose <suzuki.poulose@....com>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>,
	Fuad Tabba <tabba@...gle.com>,
	Mark Brown <broonie@...nel.org>
Cc: Dave Martin <Dave.Martin@....com>,
	linux-arm-kernel@...ts.infradead.org,
	kvmarm@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] KVM: arm64: Constrain the host to the maximum shared SVE VL with pKVM

On Thu, 12 Sep 2024 12:39:35 +0100, Mark Brown wrote:
> When pKVM saves and restores the host floating point state on a SVE system
> it programs the vector length in ZCR_EL2.LEN to be whatever the maximum VL
> for the PE is but uses a buffer allocated with kvm_host_sve_max_vl, the
> maximum VL shared by all PEs in the system. This means that if we run on a
> system where the maximum VLs are not consistent we will overflow the buffer
> on PEs which support larger VLs.
> 
> [...]

Applied to fixes, thanks!

[1/1] KVM: arm64: Constrain the host to the maximum shared SVE VL with pKVM
      commit: a9f41588a902f386b48f021f56a4c14735cd9371

Cheers,

	M.
-- 
Without deviation from the norm, progress is not possible.