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Edgecombe" , Deepak Gupta , Ard Biesheuvel , Szabolcs Nagy , Kees Cook , "H.J. Lu" , Paul Walmsley , Palmer Dabbelt , Albert Ou , Florian Weimer , Christian Brauner , Thiago Jung Bauermann , Ross Burton , David Spickett , Yury Khrustalev , Wilco Dijkstra , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, kvmarm@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org Subject: Re: [PATCH v13 16/40] KVM: arm64: Manage GCS access and registers for guests In-Reply-To: <86bk0373nq.wl-maz@kernel.org> References: <20241001-arm64-gcs-v13-0-222b78d87eee@kernel.org> <20241001-arm64-gcs-v13-16-222b78d87eee@kernel.org> <86bk0373nq.wl-maz@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/29.4 (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: broonie@kernel.org, catalin.marinas@arm.com, will@kernel.org, corbet@lwn.net, akpm@linux-foundation.org, oliver.upton@linux.dev, james.morse@arm.com, suzuki.poulose@arm.com, arnd@arndb.de, oleg@redhat.com, ebiederm@xmission.com, shuah@kernel.org, rick.p.edgecombe@intel.com, debug@rivosinc.com, ardb@kernel.org, Szabolcs.Nagy@arm.com, kees@kernel.org, hjl.tools@gmail.com, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, fweimer@redhat.com, brauner@kernel.org, thiago.bauermann@linaro.org, ross.burton@arm.com, david.spickett@arm.com, yury.khrustalev@arm.com, wilco.dijkstra@arm.com, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, kvmarm@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241002_165534_127898_BBC29D9A X-CRM114-Status: GOOD ( 15.53 ) 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 Wed, 02 Oct 2024 01:24:25 +0100, Marc Zyngier wrote: > > On Tue, 01 Oct 2024 23:58:55 +0100, > Mark Brown wrote: > > > @@ -4714,6 +4735,10 @@ void kvm_calculate_traps(struct kvm_vcpu *vcpu) > > kvm->arch.fgu[HFGxTR_GROUP] |= (HFGxTR_EL2_nPOR_EL1 | > > HFGxTR_EL2_nPOR_EL0); > > > > + if (!kvm_has_gcs(kvm)) > > + kvm->arch.fgu[HFGxTR_GROUP] |= (HFGxTR_EL2_nGCS_EL0 | > > + HFGxTR_EL2_nGCS_EL1); > > + > > Why are you still allowing the GCS instructions when GCS isn't > enabled? Scratch that, they are NOPs when GCS isn't enabled, so there shouldn't be any need for extra traps. M. -- Without deviation from the norm, progress is not possible.