On 16/12/15 08:06, Shannon Zhao wrote: > Hi, > > On 2015/12/16 15:31, Shannon Zhao wrote: >>>>>>>> But in this case, you're returning an error if it is *not* initialized. >>>>>>>> I understand that in that case you cannot return an interrupt number (-1 >>>>>>>> would be weird), but returning -EBUSY feels even more weird. >>>>>>>> >>>>>>>> I'd settle for -ENOXIO, or something similar. Anyone having a better idea? >>>>>>>> >>>> ENXIO or ENODEV would be my choice too, and add that to the >>>> Documentation clearly describing when this error code is used. >>>> >>>> By the way, why do you loop over all VCPUS to set the same value when >>>> you can't do anything per VCPU anyway? It seems to me it's either a >>>> per-VM property (that you can store on the VM data structure) or it's a >>>> true per-VCPU property? >> This is a per-VCPU property. PMU interrupt could be PPI or SPI. For PPI >> the interrupt numbers are same for each vcpu, while for SPI they are >> different, so it needs to set them separately. I planned to support both >> PPI and SPI. I think I should add support for SPI at this moment and let >> users (QEMU) to set these interrupts for each one. > > How about below vPMU Documentation? > > ARM Virtual Performance Monitor Unit (vPMU) > =========================================== > > Device types supported: > KVM_DEV_TYPE_ARM_PMU_V3 ARM Performance Monitor Unit v3 > > Instantiate one PMU instance for per VCPU through this API. > > Groups: > KVM_DEV_ARM_PMU_GRP_IRQ > Attributes: > The attr field of kvm_device_attr encodes two values: > bits: | 63 .... 32 | 31 .... 0 | > values: | vcpu_index | irq_num | > The irq_num describes the PMU overflow interrupt number for the > specified > vcpu_index vcpu. This interrupt could be a PPI or SPI, but for one > VM the > interrupt type must be same for each vcpu. > > Errors: > -ENXIO: Getting or setting this attribute is not yet supported > -ENODEV: Getting the PMU overflow interrupt number while it's not set > -EBUSY: The PMU overflow interrupt is already set > -EINVAL: Invalid vcpu_index or irq_num supplied > > Let's add at least one comment that forbids two vcpus from getting the same SPI. This is too common a mistake that we see in actual SoCs, and I don't want to see it replicated in VMs... Thanks, M. -- Jazz is not dead. It just smells funny... -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
