linux-stable.git/include/uapi/linux/iommufd.h, branch v6.9.2

iommufd: Add data structure for Intel VT-d stage-1 cache invalidation

2024-01-11T17:01:25+00:00

This adds the data structure invalidating caches for the nested domain
allocated with IOMMU_HWPT_DATA_VTD_S1 type.

Link: https://lore.kernel.org/r/20240111041015.47920-8-yi.l.liu@intel.com
Reviewed-by: Kevin Tian 
Signed-off-by: Lu Baolu 
Signed-off-by: Yi Liu 
Signed-off-by: Jason Gunthorpe

iommufd: Add IOMMU_HWPT_INVALIDATE

2024-01-11T16:55:04+00:00

In nested translation, the stage-1 page table is user-managed but cached
by the IOMMU hardware, so an update on present page table entries in the
stage-1 page table should be followed with a cache invalidation.

Add an IOMMU_HWPT_INVALIDATE ioctl to support such a cache invalidation.
It takes hwpt_id to specify the iommu_domain, and a multi-entry array to
support multiple invalidation data in one ioctl.

enum iommu_hwpt_invalidate_data_type is defined to tag the data type of
the entries in the multi-entry array.

Link: https://lore.kernel.org/r/20240111041015.47920-3-yi.l.liu@intel.com
Reviewed-by: Kevin Tian 
Co-developed-by: Nicolin Chen 
Signed-off-by: Nicolin Chen 
Signed-off-by: Yi Liu 
Signed-off-by: Jason Gunthorpe

iommu/vt-d: Disallow read-only mappings to nest parent domain

2023-10-26T14:16:34+00:00

When remapping hardware is configured by system software in scalable mode
as Nested (PGTT=011b) and with PWSNP field Set in the PASID-table-entry,
it may Set Accessed bit and Dirty bit (and Extended Access bit if enabled)
in first-stage page-table entries even when second-stage mappings indicate
that corresponding first-stage page-table is Read-Only.

As the result, contents of pages designated by VMM as Read-Only can be
modified by IOMMU via PML5E (PML4E for 4-level tables) access as part of
address translation process due to DMAs issued by Guest.

This disallows read-only mappings in the domain that is supposed to be used
as nested parent. Reference from Sapphire Rapids Specification Update [1],
errata details, SPR17. Userspace should know this limitation by checking
the IOMMU_HW_INFO_VTD_ERRATA_772415_SPR17 flag reported in the IOMMU_GET_HW_INFO
ioctl.

[1] https://www.intel.com/content/www/us/en/content-details/772415/content-details.html

Link: https://lore.kernel.org/r/20231026044216.64964-9-yi.l.liu@intel.com
Reviewed-by: Kevin Tian 
Signed-off-by: Lu Baolu 
Signed-off-by: Yi Liu 
Signed-off-by: Jason Gunthorpe

iommufd: Add data structure for Intel VT-d stage-1 domain allocation

2023-10-26T14:16:33+00:00

This adds IOMMU_HWPT_DATA_VTD_S1 for stage-1 hw_pagetable of Intel
VT-d and the corressponding data structure for userspace specified parameter
for the domain allocation.

Link: https://lore.kernel.org/r/20231026044216.64964-2-yi.l.liu@intel.com
Reviewed-by: Kevin Tian 
Signed-off-by: Yi Liu 
Signed-off-by: Jason Gunthorpe

iommufd: Add a nested HW pagetable object

2023-10-26T14:15:57+00:00

IOMMU_HWPT_ALLOC already supports iommu_domain allocation for usersapce.
But it can only allocate a hw_pagetable that associates to a given IOAS,
i.e. only a kernel-managed hw_pagetable of IOMMUFD_OBJ_HWPT_PAGING type.

IOMMU drivers can now support user-managed hw_pagetables, for two-stage
translation use cases that require user data input from the user space.

Add a new IOMMUFD_OBJ_HWPT_NESTED type with its abort/destroy(). Pair it
with a new iommufd_hwpt_nested structure and its to_hwpt_nested() helper.
Update the to_hwpt_paging() helper, so a NESTED-type hw_pagetable can be
handled in the callers, for example iommufd_hw_pagetable_enforce_rr().

Screen the inputs including the parent PAGING-type hw_pagetable that has
a need of a new nest_parent flag in the iommufd_hwpt_paging structure.

Extend the IOMMU_HWPT_ALLOC ioctl to accept an IOMMU driver specific data
input which is tagged by the enum iommu_hwpt_data_type. Also, update the
@pt_id to accept hwpt_id too besides an ioas_id. Then, use them to allocate
a hw_pagetable of IOMMUFD_OBJ_HWPT_NESTED type using the
iommufd_hw_pagetable_alloc_nested() allocator.

Link: https://lore.kernel.org/r/20231026043938.63898-8-yi.l.liu@intel.com
Signed-off-by: Nicolin Chen 
Co-developed-by: Yi Liu 
Signed-off-by: Yi Liu 
Reviewed-by: Kevin Tian 
Reviewed-by: Jason Gunthorpe 
Signed-off-by: Jason Gunthorpe

iommufd: Add a flag to skip clearing of IOPTE dirty

2023-10-24T14:58:43+00:00

VFIO has an operation where it unmaps an IOVA while returning a bitmap with
the dirty data. In reality the operation doesn't quite query the IO
pagetables that the PTE was dirty or not. Instead it marks as dirty on
anything that was mapped, and doing so in one syscall.

In IOMMUFD the equivalent is done in two operations by querying with
GET_DIRTY_IOVA followed by UNMAP_IOVA. However, this would incur two TLB
flushes given that after clearing dirty bits IOMMU implementations require
invalidating their IOTLB, plus another invalidation needed for the UNMAP.
To allow dirty bits to be queried faster, add a flag
(IOMMU_HWPT_GET_DIRTY_BITMAP_NO_CLEAR) that requests to not clear the dirty
bits from the PTE (but just reading them), under the expectation that the
next operation is the unmap. An alternative is to unmap and just
perpectually mark as dirty as that's the same behaviour as today. So here
equivalent functionally can be provided with unmap alone, and if real dirty
info is required it will amortize the cost while querying.

There's still a race against DMA where in theory the unmap of the IOVA
(when the guest invalidates the IOTLB via emulated iommu) would race
against the VF performing DMA on the same IOVA. As discussed in [0], we are
accepting to resolve this race as throwing away the DMA and it doesn't
matter if it hit physical DRAM or not, the VM can't tell if we threw it
away because the DMA was blocked or because we failed to copy the DRAM.

[0] https://lore.kernel.org/linux-iommu/20220502185239.GR8364@nvidia.com/

Link: https://lore.kernel.org/r/20231024135109.73787-10-joao.m.martins@oracle.com
Signed-off-by: Joao Martins 
Reviewed-by: Jason Gunthorpe 
Reviewed-by: Kevin Tian 
Signed-off-by: Jason Gunthorpe

iommufd: Add capabilities to IOMMU_GET_HW_INFO

2023-10-24T14:58:43+00:00

Extend IOMMUFD_CMD_GET_HW_INFO op to query generic iommu capabilities for a
given device.

Capabilities are IOMMU agnostic and use device_iommu_capable() API passing
one of the IOMMU_CAP_*. Enumerate IOMMU_CAP_DIRTY_TRACKING for now in the
out_capabilities field returned back to userspace.

Link: https://lore.kernel.org/r/20231024135109.73787-9-joao.m.martins@oracle.com
Signed-off-by: Joao Martins 
Reviewed-by: Jason Gunthorpe 
Reviewed-by: Kevin Tian 
Signed-off-by: Jason Gunthorpe

iommufd: Add IOMMU_HWPT_GET_DIRTY_BITMAP

2023-10-24T14:58:43+00:00

Connect a hw_pagetable to the IOMMU core dirty tracking
read_and_clear_dirty iommu domain op. It exposes all of the functionality
for the UAPI that read the dirtied IOVAs while clearing the Dirty bits from
the PTEs.

In doing so, add an IO pagetable API iopt_read_and_clear_dirty_data() that
performs the reading of dirty IOPTEs for a given IOVA range and then
copying back to userspace bitmap.

Underneath it uses the IOMMU domain kernel API which will read the dirty
bits, as well as atomically clearing the IOPTE dirty bit and flushing the
IOTLB at the end. The IOVA bitmaps usage takes care of the iteration of the
bitmaps user pages efficiently and without copies. Within the iterator
function we iterate over io-pagetable contigous areas that have been
mapped.

Contrary to past incantation of a similar interface in VFIO the IOVA range
to be scanned is tied in to the bitmap size, thus the application needs to
pass a appropriately sized bitmap address taking into account the iova
range being passed *and* page size ... as opposed to allowing bitmap-iova
!= iova.

Link: https://lore.kernel.org/r/20231024135109.73787-8-joao.m.martins@oracle.com
Signed-off-by: Joao Martins 
Reviewed-by: Jason Gunthorpe 
Reviewed-by: Kevin Tian 
Signed-off-by: Jason Gunthorpe

iommufd: Add IOMMU_HWPT_SET_DIRTY_TRACKING

2023-10-24T14:58:43+00:00

Every IOMMU driver should be able to implement the needed iommu domain ops
to control dirty tracking.

Connect a hw_pagetable to the IOMMU core dirty tracking ops, specifically
the ability to enable/disable dirty tracking on an IOMMU domain
(hw_pagetable id). To that end add an io_pagetable kernel API to toggle
dirty tracking:

* iopt_set_dirty_tracking(iopt, [domain], state)

The intended caller of this is via the hw_pagetable object that is created.

Internally it will ensure the leftover dirty state is cleared /right
before/ dirty tracking starts. This is also useful for iommu drivers which
may decide that dirty tracking is always-enabled at boot without wanting to
toggle dynamically via corresponding iommu domain op.

Link: https://lore.kernel.org/r/20231024135109.73787-7-joao.m.martins@oracle.com
Signed-off-by: Joao Martins 
Reviewed-by: Jason Gunthorpe 
Reviewed-by: Kevin Tian 
Signed-off-by: Jason Gunthorpe

iommufd: Add a flag to enforce dirty tracking on attach

2023-10-24T14:58:42+00:00

Throughout IOMMU domain lifetime that wants to use dirty tracking, some
guarantees are needed such that any device attached to the iommu_domain
supports dirty tracking.

The idea is to handle a case where IOMMU in the system are assymetric
feature-wise and thus the capability may not be supported for all devices.
The enforcement is done by adding a flag into HWPT_ALLOC namely:

	IOMMU_HWPT_ALLOC_DIRTY_TRACKING

.. Passed in HWPT_ALLOC ioctl() flags. The enforcement is done by creating
a iommu_domain via domain_alloc_user() and validating the requested flags
with what the device IOMMU supports (and failing accordingly) advertised).
Advertising the new IOMMU domain feature flag requires that the individual
iommu driver capability is supported when a future device attachment
happens.

Link: https://lore.kernel.org/r/20231024135109.73787-6-joao.m.martins@oracle.com
Signed-off-by: Joao Martins 
Reviewed-by: Jason Gunthorpe 
Reviewed-by: Kevin Tian 
Signed-off-by: Jason Gunthorpe