From: Marc Zyngier <maz@kernel.org>
To: Mark Brown <broonie@kernel.org>
Cc: Zenghui Yu <yuzenghui@huawei.com>,
kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
James Morse <james.morse@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Alexandru Elisei <alexandru.elisei@arm.com>,
Quentin Perret <qperret@google.com>,
Will Deacon <will@kernel.org>,
kernel-team@android.com
Subject: Re: [PATCH v2 2/5] KVM: arm64: Get rid of host SVE tracking/saving
Date: Mon, 22 Nov 2021 18:10:25 +0000 [thread overview]
Message-ID: <87v90kcb8u.wl-maz@kernel.org> (raw)
In-Reply-To: <YZvaKOLPxwFE9vQz@sirena.org.uk>
On Mon, 22 Nov 2021 17:58:00 +0000,
Mark Brown <broonie@kernel.org> wrote:
>
> On Mon, Nov 22, 2021 at 03:57:32PM +0000, Marc Zyngier wrote:
> > Zenghui Yu <yuzenghui@huawei.com> wrote:
>
> > > Nit: This removes the only user of __sve_save_state() helper. Should we
> > > still keep it in fpsimd.S?
>
> > I was in two minds about that, as I'd like to eventually be able to
> > use SVE for protected guests, where the hypervisor itself has to be in
> > charge of the FP/SVE save-restore.
>
> > But that's probably several months away, and I can always revert a
> > deletion patch if I need to, so let's get rid of it now.
>
> While we're on the subject of potential future work we might in future
> want to not disable SVE on every syscall if (as seems likely) it turns
> out that that's more performant for small vector lengths
[...]
How are you going to retrofit that into userspace? This would be an
ABI change, and I'm not sure how you'd want to deal with that
transition...
M.
--
Without deviation from the norm, progress is not possible.
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next prev parent reply other threads:[~2021-11-22 18:12 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-28 11:16 [PATCH v2 0/5] KVM: arm64: Rework FPSIMD/SVE tracking Marc Zyngier
2021-10-28 11:16 ` [PATCH v2 1/5] KVM: arm64: Reorder vcpu flag definitions Marc Zyngier
2021-10-28 11:16 ` [PATCH v2 2/5] KVM: arm64: Get rid of host SVE tracking/saving Marc Zyngier
2021-10-28 13:02 ` Mark Brown
2021-11-10 13:19 ` Zenghui Yu
2021-11-22 15:57 ` Marc Zyngier
2021-11-22 17:58 ` Mark Brown
2021-11-22 18:10 ` Marc Zyngier [this message]
2021-11-22 18:30 ` Mark Brown
2021-11-23 10:11 ` Marc Zyngier
2021-11-23 12:33 ` Mark Brown
2021-10-28 11:16 ` [PATCH v2 3/5] KVM: arm64: Introduce flag shadowing TIF_FOREIGN_FPSTATE Marc Zyngier
2021-10-28 11:16 ` [PATCH v2 4/5] KVM: arm64: Stop mapping current thread_info at EL2 Marc Zyngier
2021-10-28 11:16 ` [PATCH v2 5/5] arm64/fpsimd: Document the use of TIF_FOREIGN_FPSTATE by KVM Marc Zyngier
2021-10-28 13:14 ` Mark Brown
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