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
>>> + __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[];
>>> +};
>> 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
>
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