Re: [PATCH v1 1/1] vfio: Make migration support non experimental by default.

[Liang Yan]

On 7/14/21 6:19 AM, Kirti Wankhede wrote:
>
>
> On 7/10/2021 1:14 PM, Claudio Fontana wrote:
>> On 3/8/21 5:09 PM, Tarun Gupta wrote:
>>> VFIO migration support in QEMU is experimental as of now, which was
>>> done to
>>> provide soak time and resolve concerns regarding bit-stream.
>>> But, with the patches discussed in
>>> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.mail-archive.com%2Fqemu-devel%40nongnu.org%2Fmsg784931.html&data=04%7C01%7Ckwankhede%40nvidia.com%7C98194e8a856f4e6b611c08d943769ab5%7C43083d15727340c1b7db39efd9ccc17a%7C0%7C0%7C637614998961553398%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=A2EY9LEqGE0BSrT25h2WtWonb5oi0O%2B6%2BQmvhVf8Wd4%3D&reserved=0
>>> , we have
>>> corrected ordering of saving PCI config space and bit-stream.
>>>
>>> So, this patch proposes to make vfio migration support in QEMU to be
>>> enabled
>>> by default. Tested by successfully migrating mdev device.
>>>
>>> Signed-off-by: Tarun Gupta <targupta@nvidia.com>
>>> Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
>>> ---
>>>   hw/vfio/pci.c | 2 +-
>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
>>> index f74be78209..15e26f460b 100644
>>> --- a/hw/vfio/pci.c
>>> +++ b/hw/vfio/pci.c
>>> @@ -3199,7 +3199,7 @@ static Property vfio_pci_dev_properties[] = {
>>>       DEFINE_PROP_BIT("x-igd-opregion", VFIOPCIDevice, features,
>>>                       VFIO_FEATURE_ENABLE_IGD_OPREGION_BIT, false),
>>>       DEFINE_PROP_BOOL("", VFIOPCIDevice,
>>> -                     vbasedev.enable_migration, false),
>>> +                     vbasedev.enable_migration, true),
>>>       DEFINE_PROP_BOOL("x-no-mmap", VFIOPCIDevice, vbasedev.no_mmap,
>>> false),
>>>       DEFINE_PROP_BOOL("x-balloon-allowed", VFIOPCIDevice,
>>>                        vbasedev.ram_block_discard_allowed, false),
>>>
>>
>> Hello,
>>
>> has plain snapshot been tested?
>
> Yes.
>
>> If I issue the HMP command "savevm", and then "loadvm", will things
>> work fine?
>
> Yes
>

Hello Kirti,

I enabled x-enable-migration and did some hack on failover_pair_id,
finally made  "virsh save/restore" and "savevm/loadvm"work through.
However, it seems vGPU did not get involved in the real migration
process, the qemu trace file confirmed it, there is no vfio section for
savevm_section_start at all.

I am using kernel 5.8 and latest qemu, vGPU 12.2 with one V100. I am
wondering if there is a version compatible requirement or need extra
setup. Could you share your test setup here? Thanks in advance.

Regards,

Liang



> Thanks,
> Kirti
>