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Fri, 22 May 2026 05:49:31 +0000 Date: Fri, 22 May 2026 06:52:48 +0100 Message-ID: <87lddc9ej3.wl-maz@kernel.org> From: Marc Zyngier To: Mark Rutland Cc: Mark Brown , Oliver Upton , Joey Gouly , Catalin Marinas , Suzuki K Poulose , Will Deacon , Paolo Bonzini , Jonathan Corbet , Shuah Khan , Dave Martin , Fuad Tabba , Ben Horgan , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, Peter Maydell , Eric Auger Subject: Re: [PATCH v10 19/30] KVM: arm64: Provide assembly for SME register access In-Reply-To: References: <20260306-kvm-arm64-sme-v10-0-43f7683a0fb7@kernel.org> <20260306-kvm-arm64-sme-v10-19-43f7683a0fb7@kernel.org> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/30.1 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: mark.rutland@arm.com, broonie@kernel.org, oupton@kernel.org, joey.gouly@arm.com, catalin.marinas@arm.com, suzuki.poulose@arm.com, will@kernel.org, pbonzini@redhat.com, corbet@lwn.net, shuah@kernel.org, Dave.Martin@arm.com, tabba@google.com, ben.horgan@arm.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, peter.maydell@linaro.org, eric.auger@redhat.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false On Thu, 21 May 2026 15:51:26 +0100, Mark Rutland wrote: > > On Fri, Mar 06, 2026 at 05:01:11PM +0000, Mark Brown wrote: > > Provide versions of the SME state save and restore functions for the > > hypervisor to allow it to restore ZA and ZT for guests. > > > > Signed-off-by: Mark Brown > > --- > > arch/arm64/include/asm/kvm_hyp.h | 2 ++ > > arch/arm64/kvm/hyp/fpsimd.S | 23 +++++++++++++++++++++++ > > 2 files changed, 25 insertions(+) > > While this specific instance is simple enough, I don't think we should > continue to duplicate the low level save/restore routines between the > main kernel and KVM hyp code. > > I've sent a series that avoids the need for this, and cleans up some > other bits): > > https://lore.kernel.org/linux-arm-kernel/20260521132556.584676-1-mark.rutland@arm.com/ > > Assuming Marc and Oliver are on board, I'd prefer that we do that > cleanup first, and build the KVM SME support atop. Absolutely. The whole FP/SVE is still way too complicated, full of esoteric constructs, hard to audit, and I would really like to see it cleaned-up before stacking another layer on top. I've quickly eyeballed the KVM-specific patches yesterday, and nothing seem outlandish, so there is a good chance some of that could make it into 7.2. I plan to look at it again shortly. Thanks, M. -- Jazz isn't dead. It just smells funny.