linux-kernel - Re: [PATCH v4 0/4] KVM: arm64: Fix underallocation of storage for SVE state

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Message-ID: <CA+EHjTyCvG2KL=LPhbAf+Wo66QoC_EMk1xn+R9X-yKunHQ-JhA@mail.gmail.com>
Date: Fri, 6 Sep 2024 16:35:29 +0100
From: Fuad Tabba <tabba@...gle.com>
To: Mark Brown <broonie@...nel.org>
Cc: Dave Martin <Dave.Martin@....com>, Marc Zyngier <maz@...nel.org>, 
	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>, linux-arm-kernel@...ts.infradead.org, 
	linux-kernel@...r.kernel.org, kvmarm@...ts.linux.dev
Subject: Re: [PATCH v4 0/4] KVM: arm64: Fix underallocation of storage for SVE state

Hi,

> > Can't pKVM just hide the non symmetrically supported VLs using ZCR_EL2,
> > just as regular KVM does for the guest?
>
> > (I may be making bad assumptions about pKVM's relationship with the host
> > kernel.)
>
> That's one for the pKVM people.

Yes, but that's not really the issue here, unless I'm missing
something else. The issue is that pKVM needs to store the host's SVE
state too, to be able to restore it. So hiding non-symmetrically
supported VLs for the guests shouldn't be relevant.

Cheers,
/fuad