On 10/27/2016 12:50 PM, Alexey Kardashevskiy wrote: > 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. > Consider the example of QEMU process which creates VFIO container, QEMU in its teardown path would release the container. How could container be alive when process is gone? Kirti > > >> - 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 <kwankhede@xxxxxxxxxx> >> Signed-off-by: Neo Jia <cjia@xxxxxxxxxx> >> Change-Id: I295d6f0f2e0579b8d9882bfd8fd5a4194b97bd9a > > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
