On 2015/12/17 17:38, Marc Zyngier wrote: > On 17/12/15 08:41, Shannon Zhao wrote: >> > >> > >> > On 2015/12/17 16:33, Marc Zyngier wrote: >>> >> On Thu, 17 Dec 2015 15:22:50 +0800 >>> >> Shannon Zhao <zhaoshenglong@xxxxxxxxxx> wrote: >>> >> >>>>> >>>> >>>>> >>>> >>>>> >>>> On 2015/12/17 4:33, Christoffer Dall wrote: >>>>>>> >>>>>> On Wed, Dec 16, 2015 at 04:06:49PM +0800, 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 | >>>>> >>>> BTW, I change this Attribute to below format and pass vcpu_index through >>>>> >>>> this Attribute while pass irq_num through kvm_device_attr.addr. >>>>> >>>> Is it fine? >>>>> >>>> >>>>> >>>> bits: | 63 .... 32 | 31 .... 0 | >>>>> >>>> values: | reserved | vcpu_index | >>> >> Using the .addr field for something that is clearly not an address is >>> >> rather odd. Is there any prior usage of that field for something that >>> >> is not an address? >> > >> > I see this usage in vgic_attr_regs_access(). But if you prefer previous >> > one, I'll use that. > Ah, you're using the .addr field to point to a userspace value, not to > carry the value itself! That'd be fine by me (even if I still prefer the > original one), but I'd like others to chime in (I'm quite bad at > defining userspace stuff...). Another reason I think is that it needs to pass the irq_num to user space when calling get_attr. It could be passed via kvm_device_attr.addr while can't be passed via kvm_device_attr.attr within current framework. 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
