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
