Re: [RFC PATCH 3/6] iommu/amd: Introduce Guest-ID struct amd_iommu_vminfo

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

On 1/5/2024 9:38 PM, Jason Gunthorpe wrote:
> On Fri, Jan 05, 2024 at 08:39:56PM +0700, Suthikulpanit, Suravee wrote:
>> Hi Kevin
>>
>> On 12/15/2023 2:35 PM, Tian, Kevin wrote:
>>>> From: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
>>>> Sent: Wednesday, December 13, 2023 12:02 AM
>>>>
>>>> AMD HW-vIOMMU feature requires IOMMU driver to specify a unique 16-bit
>>>> Guest ID (GID) for each VM. This ID is used to index into various
>>>> data structures for configuring the hardware.
>>>>
>>>> Introduce amd_iommu_vminfo_hash hashtable to store per-vm
>>>> configuration,
>>>> which uses 16-bit GID as a hash key along with helper functions.
>>>>
>>>
>>> somehow it's unclear to me whether this series is only for hw
>>> supporting vf or broader hw supporting nested capability. for
>>> the latter case is GID still necessary?
>>
>> I am restructuring the series and might be moving GID stuff until later when
>> introduce broader hw support for AMD vIOMMU.
> 
> I'm hoping you can just skip enabling the viommu features and still
> have nesting? That should be OK right? The SW will manage the
> invalidations.

Correct, the part 1 only add support for nested translation (w/o 
HW-vIOMMU feature). So, SW would need to manage the invalidation.

Suravee