On 2015/12/16 17:04, Marc Zyngier wrote: > 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... Ok, will add. Thanks, -- Shannon -- 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
