Re: [PATCH v2] hw/i386/amd_iommu: Allow migration

["Suthikulpanit, Suravee" <suravee.suthikulpanit@amd.com>]

Daniel,

On 2/6/2025 4:01 PM, Daniel P. Berrangé wrote:
> On Thu, Feb 06, 2025 at 05:18:56AM +0000, Suravee Suthikulpanit wrote:
>> Add migration support for AMD IOMMU model by saving necessary AMDVIState
>> parameters for MMIO registers, device table, command buffer, and event
>> buffers.
>>
>> Signed-off-by: Suravee Suthikulpanit<suravee.suthikulpanit@amd.com>
>> ---
>> Changes from v1:
>> (https://lore.kernel.org/all/9ecffa7a-f4c6-45a5- 
>> a066-84826ccb55dd@amd.com/T/)
>> * Include ppr_log, pprlog_len, pprlog_head, pprlog_tail per Joao.
>>
>>   hw/i386/amd_iommu.c | 43 ++++++++++++++++++++++++++++++++++++++++++-
>>   1 file changed, 42 insertions(+), 1 deletion(-)
>>
>> diff --git a/hw/i386/amd_iommu.c b/hw/i386/amd_iommu.c
>> index 13af7211e1..a1940a0ab3 100644
>> --- a/hw/i386/amd_iommu.c
>> +++ b/hw/i386/amd_iommu.c
>> @@ -1673,7 +1673,48 @@ static Property amdvi_properties[] = {
>>   
>>   static const VMStateDescription vmstate_amdvi_sysbus = {
>>       .name = "amd-iommu",
>> -    .unmigratable = 1
>> +    .version_id = 1,
> IMHO we should not remove the 'unmigratable = 1'  setting, until we
> have fixed the design problem with this device, to split the creation
> of the 'AMDVI-PCI' device off from the 'amd-iommu' device, so that the
> former is user creatable.
> 
> As it stands now, there's no mechanism to guarantee that the internally
> created 'AMDVI-PCI' device gets the same PCI address properties on every
> boot. Thus it isn't safe to claim this device is migratable yet IMHO.

I'll send out v3 including the change you suggested, where we split the 
creation of AMDVI-PCI device to allow fix enumeration of amd-iommu device.

Thanks,
Suravee