On 2021/7/30 20:52, Steven Sistare wrote:
> On 7/28/2021 12:56 AM, Zheng Chuan wrote:
>> On 2021/7/20 2:38, Steven Sistare wrote:
>>> On 7/19/2021 2:10 PM, Alex Williamson wrote:
>>>> On Mon, 19 Jul 2021 13:44:08 -0400
>>>> Steven Sistare <steven.sist...@oracle.com> wrote:
>>>>
>>>>> On 7/16/2021 4:51 PM, Alex Williamson wrote:
>>>>>> On Wed, 7 Jul 2021 10:20:26 -0700
>>>>>> Steve Sistare <steven.sist...@oracle.com> wrote:
>>>>>>
>>>>>>> Finish cpr for vfio-pci by preserving eventfd's and vector state.
>>>>>>>
>>>>>>> Signed-off-by: Steve Sistare <steven.sist...@oracle.com>
>>>>>>> ---
>>>>>>> hw/vfio/pci.c | 118
>>>>>>> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
>>>>>>> 1 file changed, 116 insertions(+), 2 deletions(-)
>>>>>>>
>>>>>>> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
>>>>>>> index 0f5c542..07bd360 100644
>>>>>>> --- a/hw/vfio/pci.c
>>>>>>> +++ b/hw/vfio/pci.c
>>>>>> ...
>>>>>>> @@ -3295,14 +3329,91 @@ static void vfio_merge_config(VFIOPCIDevice
>>>>>> *vdev)
>>>>>>> g_free(phys_config);
>>>>>>> }
>>>>>>>
>>>>>>> +static int vfio_pci_pre_save(void *opaque)
>>>>>>> +{
>>>>>>> + VFIOPCIDevice *vdev = opaque;
>>>>>>> + PCIDevice *pdev = &vdev->pdev;
>>>>>>> + int i;
>>>>>>> +
>>>>>>> + if (vfio_pci_read_config(pdev, PCI_INTERRUPT_PIN, 1)) {
>>>>>>> + error_report("%s: cpr does not support vfio-pci INTX",
>>>>>>> + vdev->vbasedev.name);
>>>>>>> + }
>>>>>>
>>>>>> You're not only not supporting INTx, but devices that support INTx, so
>>>>>> this only works on VFs. Why? Is this just out of scope or is there
>>>>>> something fundamentally difficult about it?
>>>>>>
>>>>>> This makes me suspect there's a gap in INTx routing setup if it's more
>>>>>> than just another eventfd to store and setup. If we hot-add a device
>>>>>> using INTx after cpr restart, are we going to find problems? Thanks,
>>>>>
>>>>> It could be supported, but requires more code (several event fd's plus
>>>>> other state in VFIOINTx
>>>>> to save and restore) for a case that does not seem very useful (a
>>>>> directly assigned device that
>>>>> only supports INTx ?).
>>>>
>>>> It's not testing that the device *only* supports INTx, it's testing
>>>> that the device supports INTx _at_all_. That effectively means this
>>>> excludes anything other than an SR-IOV VF. There are plenty of valid
>>>> and useful cases of assigning PFs, most of which support INTx even if
>>>> we don't expect that's their primary operational mode. Thanks,
>>>
>>> OK, I'll look into it. If this proves problematic, how do you feel about
>>> deferring
>>> INTx support to a later patch?
>>>
>> I am curious about that does cpr restart mode work for GPU passthrough?
>
> It should work for any vfio device (after I fix the INTX limitation), but I
> have not tested
> a GPU yet.
>
> - Steve
> .
Yes, The GPU may switch frequently between INTX and MSI, and cpr should support
both of them:)
Thanks.
>
--
Regards.
Chuan
