> -----Original Message-----
> From: Alex Williamson [mailto:alex.william...@redhat.com]
> Sent: Wednesday, November 26, 2014 12:10 AM
> To: Eric Auger
> Cc: Wu, Feng; pbonz...@redhat.com; g...@kernel.org; kvm@vger.kernel.org
> Subject: Re: [RFC PATCH v2 1/2] KVM: kvm-vfio: User API for VT-d
> Posted-Interrupts
>
> 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...@intel.com>
> > > ---
> > > 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 */
> > > };
> > >
> > > +struct kvm_posted_intr {
> > > + __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 */
> > > +};
> > 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. Ideally the
> code in virt/kvm/vfio.c would be almost entirely shared and just make
> different arch_foo() callouts. The PCI smarts in 2/2 here should
> probably be moved out to that same arch_ code. Thanks,
>
> Alex
That would be great if we share the same data structure!
Thanks,
Feng
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