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?
- Steve
