On Mon, Jul 31, 2023 at 04:54:04AM -0700, Reiji Watanabe wrote: > Hi Oliver, > > > This doesn't actually disallow userspace from configuring a vPMU, it > > only hides the KVM cap. kvm_host_pmu_init() will still insert the host > > PMU instance in the list of valid PMUs, and there doesn't appear to be > > any check against the static key anywhere on that path. > > In v6.5-rc3, which I used as the base, or even in v6.5-rc4, > it appears kvm_reset_vcpu() checks against the static key. > So, the initial KVM_ARM_VCPU_INIT with vPMU configured will > fail on the systems. Or am I missing something ? (Or is that > going to be removed by other patches that are already queued?) No, I definitely missed something, sorry for the noise! I had only checked the PMU attributes, forgot about feature flags for a moment. > > I actually prefer where we flip the static key, as PMU context switching > > depends on both KVM support as well as the PMU driver coming up successfully. > > Instead, you could hoist the check against the sanitised PMU version into > > kvm_host_pmu_init(), maybe something like: > > Thank you, it looks better. I will fix this in v3. Sounds good, thanks! -- Best, Oliver
