On Tue, 2014-12-02 at 02:08 +0000, Wu, Feng wrote: > > > -----Original Message----- > > From: Eric Auger [mailto:eric.auger@xxxxxxxxxx] > > Sent: Monday, December 01, 2014 6:10 PM > > To: Alex Williamson > > Cc: Wu, Feng; pbonzini@xxxxxxxxxx; gleb@xxxxxxxxxx; kvm@xxxxxxxxxxxxxxx > > Subject: Re: [RFC PATCH v2 1/2] KVM: kvm-vfio: User API for VT-d > > Posted-Interrupts > > > > On 11/25/2014 05:10 PM, Alex Williamson wrote: > > > On Tue, 2014-11-25 at 16:01 +0100, Eric Auger wrote: > > >> On 11/25/2014 01:23 PM, Feng Wu wrote: > > >>> This patch adds and documents a new attribute > > >>> KVM_DEV_VFIO_DEVICE_POSTING_IRQ in KVM_DEV_VFIO_DEVICE > > group. > > >>> This new attribute is used for VT-d Posted-Interrupts. > > >>> > > >>> When guest OS changes the interrupt configuration for an > > >>> assigned device, such as, MSI/MSIx data/address fields, > > >>> QEMU will use this IRQ attribute to tell KVM to update the > > >>> related IRTE according the VT-d Posted-Interrrupts Specification, > > >>> such as, the guest vector should be updated in the related IRTE. > > >>> > > >>> Signed-off-by: Feng Wu <feng.wu@xxxxxxxxx> > > >>> --- > > >>> Documentation/virtual/kvm/devices/vfio.txt | 9 +++++++++ > > >>> include/uapi/linux/kvm.h | 10 ++++++++++ > > >>> 2 files changed, 19 insertions(+), 0 deletions(-) > > >>> > > >>> diff --git a/Documentation/virtual/kvm/devices/vfio.txt > > b/Documentation/virtual/kvm/devices/vfio.txt > > >>> index f7aff29..39dee86 100644 > > >>> --- a/Documentation/virtual/kvm/devices/vfio.txt > > >>> +++ b/Documentation/virtual/kvm/devices/vfio.txt > > >>> @@ -42,3 +42,12 @@ activated before VFIO_DEVICE_SET_IRQS has been > > called to trigger the IRQ > > >>> or associate an eventfd to it. Unforwarding can only be called while the > > >>> signaling has been disabled with VFIO_DEVICE_SET_IRQS. If this > > condition is > > >>> not satisfied, the command returns an -EBUSY. > > >>> + > > >>> + KVM_DEV_VFIO_DEVICE_POSTING_IRQ: Use posted interrtups > > mechanism to post > > >>> + the IRQ to guests. > > >>> +For this attribute, kvm_device_attr.addr points to a kvm_posted_intr > > struct. > > >>> + > > >>> +When guest OS changes the interrupt configuration for an assigned > > device, > > >>> +such as, MSI/MSIx data/address fields, QEMU will use this IRQ attribute > > >>> +to tell KVM to update the related IRTE according the VT-d > > Posted-Interrrupts > > >>> +Specification, such as, the guest vector should be updated in the related > > IRTE. > > >>> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h > > >>> index a269a42..e5f86ad 100644 > > >>> --- a/include/uapi/linux/kvm.h > > >>> +++ b/include/uapi/linux/kvm.h > > >>> @@ -949,6 +949,7 @@ struct kvm_device_attr { > > >>> #define KVM_DEV_VFIO_DEVICE 2 > > >>> #define KVM_DEV_VFIO_DEVICE_FORWARD_IRQ 1 > > >>> #define KVM_DEV_VFIO_DEVICE_UNFORWARD_IRQ 2 > > >>> +#define KVM_DEV_VFIO_DEVICE_POSTING_IRQ 3 > > >>> > > >>> enum kvm_device_type { > > >>> KVM_DEV_TYPE_FSL_MPIC_20 = 1, > > >>> @@ -973,6 +974,15 @@ struct kvm_arch_forwarded_irq { > > >>> __u32 gsi; /* gsi, ie. virtual IRQ number */ > > >>> }; > > >>> > > Hi Feng, Alex, > > I am currently reworking my code to use something closer to this struct. > > Would you agree with following changes? > > >>> +struct kvm_posted_intr { > > kvm_posted_irq > > Hi Alex, > > Do you mean changing the structure name to "kvm_posted_irq"? I am okay > If you think this name is also suitable for ARM forwarded irq. Or we can find > a more common name, such as "struct kvm_accel_irq", what is your opinion, Alex? I'd think something like struct kvm_vfio_dev_irq describes it fairly well. > > >>> + __u32 argsz; > > >>> + __u32 fd; /* file descriptor of the VFIO device */ > > >>> + __u32 index; /* VFIO device IRQ index */ > > >>> + __u32 start; > > >>> + __u32 count; > > >>> + int virq[0]; /* gsi, ie. virtual IRQ number */ > > __u32 gsi[]; > > I think this change is okay to me. If Alex also agree, I will follow this in the > next post. > > > >>> +}; > > >> Hi Feng, > > >> > > >> This struct could be used by arm code too. If Alex agrees I could use > > >> that one instead. We just need to find a common sensible name > > > > > > Yep, the interface might as well support batch setup. The vfio code > > > uses -1 for teardown if we want to avoid FORWARD vs UNFORWARD we could > > > let the data in the structure define which operation to do. > > > > In case we remove the unforward and use fd=1 to tear down, the virq=gsi > > must uniquely identify the struct. For ARM I think this is true, we > > cannot have several physical IRQ forwarded to the same GSI. I don't know > > about posted irqs or other archs. It makes more sense to me that fd is the real vfio_device fd that we uniquely match to existing forwarded/posted IRQs by {vfio_device,index,start[count]}. If gsi was then signed, passing -1 could be used to teardown that forward/posting. Passing fd=1, ie. stdout, is pretty non-intuitive to me. Thanks, Alex -- 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
