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Tue, 14 Jul 2026 15:19:31 +0000 Date: Tue, 14 Jul 2026 16:19:30 +0100 Message-ID: <86ik6hoayl.wl-maz@kernel.org> From: Marc Zyngier To: Fuad Tabba Cc: Oliver Upton , kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Catalin Marinas , Will Deacon , Joey Gouly , Steffen Eiden , Suzuki K Poulose , Zenghui Yu , Vincent Donnefort , Quentin Perret , Sebastian Ene , Hyunwoo Kim , Fuad Tabba Subject: Re: [PATCH v5 2/8] KVM: arm64: Make vcpu_{read,write}_sys_reg available to HYP code In-Reply-To: <20260714101601.4142645-3-fuad.tabba@linux.dev> References: <20260714101601.4142645-1-fuad.tabba@linux.dev> <20260714101601.4142645-3-fuad.tabba@linux.dev> 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) 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: fuad.tabba@linux.dev, oupton@kernel.org, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, catalin.marinas@arm.com, will@kernel.org, joey.gouly@arm.com, seiden@linux.ibm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, vdonnefort@google.com, qperret@google.com, sebastianene@google.com, imv4bel@gmail.com, tabba@google.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, 14 Jul 2026 11:15:55 +0100, Fuad Tabba wrote: > > The vcpu_{read,write}_sys_reg() accessors are only valid on a VHE host, > so helpers built on them such as kvm_vcpu_set_be()/kvm_vcpu_is_be() > cannot be shared with hyp code. exception.c already wraps them in local > helpers that pick the host- or hyp-side accessor via has_vhe(). > > Rename the host-only implementations to __vcpu_{read,write}_sysreg_vhe() I'm a bit puzzled by this. There is nothing that makes these functions VHE-specific. Look at where they are called from: plenty of non-VHE uses. These helpers are the canonical accessors for any system register, and they don't cater for any particular mode. m. -- Without deviation from the norm, progress is not possible.