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X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Marc Zyngier , nd , "kvm@vger.kernel.org" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Christoffer, On 24/01/2019 14:00, Christoffer Dall wrote: > Note that to avoid mapping the kvm_vmid_bits variable into hyp, we > simply forego the masking of the vmid value in kvm_get_vttbr and rely on > update_vmid to always assign a valid vmid value (within the supported > range). [...] > - kvm->arch.vmid = kvm_next_vmid; > + vmid->vmid = kvm_next_vmid; > kvm_next_vmid++; > - kvm_next_vmid &= (1 << kvm_vmid_bits) - 1; > - > - /* update vttbr to be used with the new vmid */ > - pgd_phys = virt_to_phys(kvm->arch.pgd); > - BUG_ON(pgd_phys & ~kvm_vttbr_baddr_mask(kvm)); > - vmid = ((u64)(kvm->arch.vmid) << VTTBR_VMID_SHIFT) & VTTBR_VMID_MASK(kvm_vmid_bits); > - kvm->arch.vttbr = kvm_phys_to_vttbr(pgd_phys) | vmid | cnp; > + kvm_next_vmid &= (1 << kvm_get_vmid_bits()) - 1; The arm64 version of kvm_get_vmid_bits does not look cheap. Indeed it required to read the sanitized value of SYS_ID_AA64MMFR1_EL1 that is implemented using the function bsearch. So wouldn't it be better to keep kvm_vmid_bits variable for use in update_vttbr()? Cheers, -- Julien Grall _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel