Hi Drew, On 6/3/20 12:21 PM, Andrew Jones wrote: > On Wed, Jun 03, 2020 at 11:59:23AM +0200, Auger Eric wrote: >> Hi Drew, >> >> On 6/3/20 11:37 AM, Andrew Jones wrote: >>> On Mon, Jun 01, 2020 at 03:04:33PM +0000, Salil Mehta wrote: >>>> Hello, >>>> I could see below within function fdt_add_pmu_nodes() part of >>>> hw/arm/virt.c during virt machine initialization time: >>>> >>>> Observation: >>>> In below function, support of PMU feature is being checked for >>>> each vcpu and if the PMU is found part of the features then PMU >>>> is initialized with in the host/KVM. But if there is even one >>>> vcpu which is found to not support the PMU then loop is exited >>>> and PMU is not initialized for the rest of the vcpus as well. >>>> >>>> Questions: >>>> Q1. Not sure what is the logic of the premature exit and not >>>> continuing with further checks and initialization of other >>>> VCPU PMUs? >>> >>> KVM requires all VCPUs to have a PMU if one does. >> >> I fail to find where this is enforced? Do you know the place? > > kvm_vcpu_set_target(), called from KVM_ARM_VCPU_INIT. It ensures > all VCPUs have identical features selected. The PMU requires a > VCPU feature (KVM_ARM_VCPU_PMU_V3) to be set. OK thanks!
Eric > > Thanks, > drew >