On 18/10/16 08:22, Kirti Wankhede wrote: > VFIO IOMMU drivers are designed for the devices which are IOMMU capable. > Mediated device only uses IOMMU APIs, the underlying hardware can be > managed by an IOMMU domain. > > Aim of this change is: > - To use most of the code of TYPE1 IOMMU driver for mediated devices > - To support direct assigned device and mediated device in single module > > Added two new callback functions to struct vfio_iommu_driver_ops. Backend > IOMMU module that supports pining and unpinning pages for mdev devices > should provide these functions. > Added APIs for pining and unpining pages to VFIO module. These calls back > into backend iommu module to actually pin and unpin pages. > > This change adds pin and unpin support for mediated device to TYPE1 IOMMU > backend module. More details: > - When iommu_group of mediated devices is attached, task structure is > cached which is used later to pin pages and page accounting.
For SPAPR TCE IOMMU driver, I ended up caching mm_struct with atomic_inc(&container->mm->mm_count) (patches are on the way) instead of using @current or task as the process might be gone while VFIO container is still alive and @mm might be needed to do proper cleanup; this might not be an issue with this patchset now but still you seem to only use @mm from task_struct. > - It keeps track of pinned pages for mediated domain. This data is used to > verify unpinning request and to unpin remaining pages while detaching, if > there are any. > - Used existing mechanism for page accounting. If iommu capable domain > exist in the container then all pages are already pinned and accounted. > Accouting for mdev device is only done if there is no iommu capable > domain in the container. > - Page accouting is updated on hot plug and unplug mdev device and pass > through device. > > Tested by assigning below combinations of devices to a single VM: > - GPU pass through only > - vGPU device only > - One GPU pass through and one vGPU device > - Linux VM hot plug and unplug vGPU device while GPU pass through device > exist > - Linux VM hot plug and unplug GPU pass through device while vGPU device > exist > > Signed-off-by: Kirti Wankhede <kwankh...@nvidia.com> > Signed-off-by: Neo Jia <c...@nvidia.com> > Change-Id: I295d6f0f2e0579b8d9882bfd8fd5a4194b97bd9a -- Alexey
