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Message-ID: <bf95f910-e837-4d79-8218-18d234ece730@intel.com> Date: Wed, 25 Sep 2024 18:30:20 +0800 From: Yi Liu <yi.l.liu@...el.com> To: Nicolin Chen <nicolinc@...dia.com>, <jgg@...dia.com>, <kevin.tian@...el.com>, <will@...nel.org> CC: <joro@...tes.org>, <suravee.suthikulpanit@....com>, <robin.murphy@....com>, <dwmw2@...radead.org>, <baolu.lu@...ux.intel.com>, <shuah@...nel.org>, <linux-kernel@...r.kernel.org>, <iommu@...ts.linux.dev>, <linux-arm-kernel@...ts.infradead.org>, <linux-kselftest@...r.kernel.org>, <eric.auger@...hat.com>, <jean-philippe@...aro.org>, <mdf@...nel.org>, <mshavit@...gle.com>, <shameerali.kolothum.thodi@...wei.com>, <smostafa@...gle.com> Subject: Re: [PATCH v2 00/19] iommufd: Add VIOMMU infrastructure (Part-1) Hi Nic, On 2024/8/28 00:59, Nicolin Chen wrote: > This series introduces a new VIOMMU infrastructure and related ioctls. > > IOMMUFD has been using the HWPT infrastructure for all cases, including a > nested IO page table support. Yet, there're limitations for an HWPT-based > structure to support some advanced HW-accelerated features, such as CMDQV > on NVIDIA Grace, and HW-accelerated vIOMMU on AMD. Even for a multi-IOMMU > environment, it is not straightforward for nested HWPTs to share the same > parent HWPT (stage-2 IO pagetable), with the HWPT infrastructure alone. could you elaborate a bit for the last sentence in the above paragraph? > > The new VIOMMU object is an additional layer, between the nested HWPT and > its parent HWPT, to give to both the IOMMUFD core and an IOMMU driver an > additional structure to support HW-accelerated feature: > ---------------------------- > ---------------- | | paging_hwpt0 | > | hwpt_nested0 |--->| viommu0 ------------------ > ---------------- | | HW-accel feats | > ---------------------------- > > On a multi-IOMMU system, the VIOMMU object can be instanced to the number > of vIOMMUs in a guest VM, while holding the same parent HWPT to share the > 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: > ---------------------------- > ---------------- | | paging_hwpt0 | > | hwpt_nested0 |--->| viommu0 ------------------ > ---------------- | | VMID0 | > ---------------------------- > ---------------------------- > ---------------- | | paging_hwpt0 | > | hwpt_nested1 |--->| viommu1 ------------------ > ---------------- | | VMID1 | > ---------------------------- > > As an initial part-1, add ioctls to support a VIOMMU-based invalidation: > IOMMUFD_CMD_VIOMMU_ALLOC to allocate a VIOMMU object > IOMMUFD_CMD_VIOMMU_SET/UNSET_VDEV_ID to set/clear device's virtual ID > (Resue IOMMUFD_CMD_HWPT_INVALIDATE for a VIOMMU object to flush cache > by a given driver data) > > Worth noting that the VDEV_ID is for a per-VIOMMU device list for drivers > to look up the device's physical instance from its virtual ID in a VM. It > is essential for a VIOMMU-based invalidation where the request contains a > device's virtual ID for its device cache flush, e.g. ATC invalidation. > > As for the implementation of the series, add an IOMMU_VIOMMU_TYPE_DEFAULT > type for a core-allocated-core-managed VIOMMU object, allowing drivers to > simply hook a default viommu ops for viommu-based invalidation alone. And > provide some viommu helpers to drivers for VDEV_ID translation and parent > domain lookup. Add VIOMMU invalidation support to ARM SMMUv3 driver for a > real world use case. This adds supports of arm-smmuv-v3's CMDQ_OP_ATC_INV > and CMDQ_OP_CFGI_CD/ALL commands, supplementing HWPT-based invalidations. > > In the future, drivers will also be able to choose a driver-managed type > to hold its own structure by adding a new type to enum iommu_viommu_type. > More VIOMMU-based structures and ioctls will be introduced in part-2/3 to > support a driver-managed VIOMMU, e.g. VQUEUE object for a HW accelerated > queue, VIRQ (or VEVENT) object for IRQ injections. Although we repurposed > the VIOMMU object from an earlier RFC discussion, for a referece: > https://lore.kernel.org/all/cover.1712978212.git.nicolinc@nvidia.com/ > > This series is on Github: > https://github.com/nicolinc/iommufd/commits/iommufd_viommu_p1-v2 > Paring QEMU branch for testing: > https://github.com/nicolinc/qemu/commits/wip/for_iommufd_viommu_p1-v2 > > Changelog > v2 > * Limited vdev_id to one per idev > * Added a rw_sem to protect the vdev_id list > * Reworked driver-level APIs with proper lockings > * Added a new viommu_api file for IOMMUFD_DRIVER config > * Dropped useless iommu_dev point from the viommu structure > * Added missing index numnbers to new types in the uAPI header > * Dropped IOMMU_VIOMMU_INVALIDATE uAPI; Instead, reuse the HWPT one > * Reworked mock_viommu_cache_invalidate() using the new iommu helper > * Reordered details of set/unset_vdev_id handlers for proper lockings > * Added arm_smmu_cache_invalidate_user patch from Jason's nesting series > v1 > https://lore.kernel.org/all/cover.1723061377.git.nicolinc@nvidia.com/ > > Thanks! > Nicolin > > Jason Gunthorpe (3): > iommu: Add iommu_copy_struct_from_full_user_array helper > iommu/arm-smmu-v3: Allow ATS for IOMMU_DOMAIN_NESTED > iommu/arm-smmu-v3: Update comments about ATS and bypass > > Nicolin Chen (16): > iommufd: Reorder struct forward declarations > iommufd/viommu: Add IOMMUFD_OBJ_VIOMMU and IOMMU_VIOMMU_ALLOC ioctl > iommu: Pass in a viommu pointer to domain_alloc_user op > iommufd: Allow pt_id to carry viommu_id for IOMMU_HWPT_ALLOC > iommufd/selftest: Add IOMMU_VIOMMU_ALLOC test coverage > iommufd/viommu: Add IOMMU_VIOMMU_SET/UNSET_VDEV_ID ioctl > iommufd/selftest: Add IOMMU_VIOMMU_SET/UNSET_VDEV_ID test coverage > iommufd/viommu: Add cache_invalidate for IOMMU_VIOMMU_TYPE_DEFAULT > iommufd: Allow hwpt_id to carry viommu_id for IOMMU_HWPT_INVALIDATE > iommufd/viommu: Add vdev_id helpers for IOMMU drivers > iommufd/selftest: Add mock_viommu_invalidate_user op > iommufd/selftest: Add IOMMU_TEST_OP_DEV_CHECK_CACHE test command > iommufd/selftest: Add VIOMMU coverage for IOMMU_HWPT_INVALIDATE ioctl > iommufd/viommu: Add iommufd_viommu_to_parent_domain helper > iommu/arm-smmu-v3: Add arm_smmu_cache_invalidate_user > iommu/arm-smmu-v3: Add arm_smmu_viommu_cache_invalidate > > drivers/iommu/amd/iommu.c | 1 + > drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 218 ++++++++++++++- > drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 3 + > drivers/iommu/intel/iommu.c | 1 + > drivers/iommu/iommufd/Makefile | 5 +- > drivers/iommu/iommufd/device.c | 12 + > drivers/iommu/iommufd/hw_pagetable.c | 59 +++- > drivers/iommu/iommufd/iommufd_private.h | 37 +++ > drivers/iommu/iommufd/iommufd_test.h | 30 ++ > drivers/iommu/iommufd/main.c | 12 + > drivers/iommu/iommufd/selftest.c | 101 ++++++- > drivers/iommu/iommufd/viommu.c | 196 +++++++++++++ > drivers/iommu/iommufd/viommu_api.c | 53 ++++ > include/linux/iommu.h | 56 +++- > include/linux/iommufd.h | 51 +++- > include/uapi/linux/iommufd.h | 117 +++++++- > tools/testing/selftests/iommu/iommufd.c | 259 +++++++++++++++++- > tools/testing/selftests/iommu/iommufd_utils.h | 126 +++++++++ > 18 files changed, 1299 insertions(+), 38 deletions(-) > create mode 100644 drivers/iommu/iommufd/viommu.c > create mode 100644 drivers/iommu/iommufd/viommu_api.c > -- Regards, Yi Liu
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