From: Nicolin Chen nicolinc@nvidia.com Sent: Wednesday, September 11, 2024 3:41 PM
On Wed, Sep 11, 2024 at 07:18:10AM +0000, Tian, Kevin wrote:
From: Nicolin Chen nicolinc@nvidia.com Sent: Wednesday, September 11, 2024 3:08 PM
On Wed, Sep 11, 2024 at 06:12:21AM +0000, Tian, Kevin wrote:
From: Nicolin Chen nicolinc@nvidia.com Sent: Wednesday, August 28, 2024 1:00 AM
stage-2 IO pagetable. Each VIOMMU then just need to only allocate its
own
VMID to attach the shared stage-2 IO pagetable to the physical IOMMU:
this reads like 'VMID' is a virtual ID allocated by vIOMMU. But from the entire context it actually means the physical 'VMID' allocated on the associated physical IOMMU, correct?
Quoting Jason's narratives, a VMID is a "Security namespace for guest owned ID". The allocation, using SMMU as an example, should
the VMID alone is not a namespace. It's one ID to tag another namespace.
be a part of vIOMMU instance allocation in the host SMMU driver. Then, this VMID will be used to mark the cache tags. So, it is still a software allocated ID, while HW would use it too.
VMIDs are physical resource belonging to the host SMMU driver.
Yes. Just the lifecycle of a VMID is controlled by a vIOMMU, i.e. the guest.
but I got your original point that it's each vIOMMU gets an unique VMID from the host SMMU driver, not exactly that each vIOMMU maintains its own VMID namespace. that'd be a different concept.
What's a VMID namespace actually? Please educate me :)
I meant the 16bit VMID pool under each SMMU.