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[2003:c9:3f4c:2400:1316:a1e5:9825:8370]) by smtp.gmail.com with ESMTPSA id fb17-20020a05622a481100b00434383f2518sm679808qtb.87.2024.04.05.05.01.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 05 Apr 2024 05:01:13 -0700 (PDT) From: Sebastian Ott To: linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org Cc: Marc Zyngier , Oliver Upton , James Morse , Suzuki K Poulose , Catalin Marinas , Will Deacon Subject: [PATCH 0/4] KVM: arm64: emulation for CTR_EL0 Date: Fri, 5 Apr 2024 14:01:04 +0200 Message-ID: <20240405120108.11844-1-sebott@redhat.com> X-Mailer: git-send-email 2.44.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Hej folks, I'm looking into supporting migration between 2 Ampere Altra (Max) machines (using Neoverse-N1). They are almost identical regarding their feature id register state except for CTR_EL0.DIC which is set on one machine but not the other. CTR_EL0 is currently marked as invariant and migrating a VM between those 2 machines using qemu fails. I've send this out as an RFC before [0]. What I've changed here based on feedback I've got from Marc was: * store the emulated value per VM and not per VCPU * allow to change more values than just the DIC bit * only trap guest access to that reg when needed * make sure to not present the guest with an inconsistent register set Patch 2 adds a ctr_el0 member to struct kvm_arch - would it be preferred to add it into kvm->arch.id_regs[] (this would mean to increase that array 4x)? Patch 3 resets CLIDR_EL1 after a write to CTR_EL0 potentially changing the value for CLIDR_EL1 - would that be ok for userspace? Thanks, Sebastian [0]: https://lore.kernel.org/all/20240318111636.10613-1-sebott@redhat.com/T/ Sebastian Ott (4): KVM: arm64: change return value in arm64_check_features() KVM: arm64: maintain per VM value for CTR_EL0 KVM: arm64: add emulation for CTR_EL0 register KVM: arm64: show writable masks for feature registers arch/arm64/include/asm/kvm_host.h | 1 + arch/arm64/kvm/sys_regs.c | 131 ++++++++++++++++++++---------- 2 files changed, 89 insertions(+), 43 deletions(-) -- 2.42.0