> -----Original Message----- > From: Eric Auger [mailto:eric.au...@linaro.org] > Sent: Monday, December 01, 2014 6:10 PM > To: Alex Williamson > 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 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...@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 */ > >>> }; > >>> > 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? > >>> + __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. Thanks, Feng > >>> +}; > >> 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. > > Best Regards > > Eric > 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 > >
