On Thu, Nov 4, 2021 at 2:39 PM Reiji Watanabe <reijiw@xxxxxxxxxx> wrote: > > Hi Oliver, > > On Thu, Nov 4, 2021 at 9:14 AM Oliver Upton <oupton@xxxxxxxxxx> wrote: > > > > Hi Reiji, > > > > On Tue, Nov 02, 2021 at 11:24:54PM -0700, Reiji Watanabe wrote: > > > Extend sys_regs[] of kvm_cpu_context for ID registers and save ID > > > registers' sanitized value in the array for the vCPU at the first > > > vCPU reset. Use the saved ones when ID registers are read by > > > userspace (via KVM_GET_ONE_REG) or the guest. > > > > Based on my understanding of the series, it appears that we require the > > CPU identity to be the same amongst all vCPUs in a VM. Is there any > > value in keeping a single copy in kvm_arch? > > Yes, that's a good point. > It reminded me that the idea bothered me after we discussed a similar > case about your counter offset patches, but I didn't seriously > consider that. > > Thank you for bringing this up. > I will look into keeping it per VM in kvm_arch. I just remembered that I made the prototype that kept ID registers per VM as the option B (, which introduced per VM ID register configuration API though...). Anyway, I've noticed that requiring the consistency of ID registers amongst vCPUs in a VM affects KVM_ARM_VCPU_INIT API, with which userspace can currently configure different features for each vCPUs. I'm not sure if any existing userspace program practically does that though. Now, I think I should rather remove that consistency requirement... (at least for features that can be configured by KVM_ARM_VCPU_INIT) Thanks, Reiji _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm