The iommu_suspend() syscore suspend callback is invoked with IRQ disabled.
Allocating memory with the GFP_KERNEL flag may re-enable IRQs during
the suspend callback, which can cause intermittent suspend/hibernation
problems with the following kernel traces:
Calling iommu_suspend+0x0/0x1d0
------------[ cut here ]------------
WARNING: CPU: 0 PID: 15 at kernel/time/timekeeping.c:868 ktime_get+0x9b/0xb0
...
CPU: 0 PID: 15 Comm: rcu_preempt Tainted: G U E 6.3-intel #r1
RIP: 0010:ktime_get+0x9b/0xb0
...
Call Trace:
<IRQ>
tick_sched_timer+0x22/0x90
? __pfx_tick_sched_timer+0x10/0x10
__hrtimer_run_queues+0x111/0x2b0
hrtimer_interrupt+0xfa/0x230
__sysvec_apic_timer_interrupt+0x63/0x140
sysvec_apic_timer_interrupt+0x7b/0xa0
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x1f/0x30
...
------------[ cut here ]------------
Interrupts enabled after iommu_suspend+0x0/0x1d0
WARNING: CPU: 0 PID: 27420 at drivers/base/syscore.c:68 syscore_suspend+0x147/0x270
CPU: 0 PID: 27420 Comm: rtcwake Tainted: G U W E 6.3-intel #r1
RIP: 0010:syscore_suspend+0x147/0x270
...
Call Trace:
<TASK>
hibernation_snapshot+0x25b/0x670
hibernate+0xcd/0x390
state_store+0xcf/0xe0
kobj_attr_store+0x13/0x30
sysfs_kf_write+0x3f/0x50
kernfs_fop_write_iter+0x128/0x200
vfs_write+0x1fd/0x3c0
ksys_write+0x6f/0xf0
__x64_sys_write+0x1d/0x30
do_syscall_64+0x3b/0x90
entry_SYSCALL_64_after_hwframe+0x72/0xdc
Given that only 4 words memory is needed, avoid the memory allocation in
iommu_suspend().
CC: stable@kernel.org
Fixes: 33e0715710 ("iommu/vt-d: Avoid GFP_ATOMIC where it is not needed")
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Tested-by: Ooi, Chin Hao <chin.hao.ooi@intel.com>
Link: https://lore.kernel.org/r/20230921093956.234692-1-rui.zhang@intel.com
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20230925120417.55977-2-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Pull iommu updates from Joerg Roedel:
"Core changes:
- Consolidate probe_device path
- Make the PCI-SAC IOVA allocation trick PCI-only
AMD IOMMU:
- Consolidate PPR log handling
- Interrupt handling improvements
- Refcount fixes for amd_iommu_v2 driver
Intel VT-d driver:
- Enable idxd device DMA with pasid through iommu dma ops
- Lift RESV_DIRECT check from VT-d driver to core
- Miscellaneous cleanups and fixes
ARM-SMMU drivers:
- Device-tree binding updates:
- Add additional compatible strings for Qualcomm SoCs
- Allow ASIDs to be configured in the DT to work around Qualcomm's
broken hypervisor
- Fix clocks for Qualcomm's MSM8998 SoC
- SMMUv2:
- Support for Qualcomm's legacy firmware implementation featured
on at least MSM8956 and MSM8976
- Match compatible strings for Qualcomm SM6350 and SM6375 SoC
variants
- SMMUv3:
- Use 'ida' instead of a bitmap for VMID allocation
- Rockchip IOMMU:
- Lift page-table allocation restrictions on newer hardware
- Mediatek IOMMU:
- Add MT8188 IOMMU Support
- Renesas IOMMU:
- Allow PCIe devices
.. and the usual set of cleanups an smaller fixes"
* tag 'iommu-updates-v6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu: (64 commits)
iommu: Explicitly include correct DT includes
iommu/amd: Remove unused declarations
iommu/arm-smmu-qcom: Add SM6375 SMMUv2
iommu/arm-smmu-qcom: Add SM6350 DPU compatible
iommu/arm-smmu-qcom: Add SM6375 DPU compatible
iommu/arm-smmu-qcom: Sort the compatible list alphabetically
dt-bindings: arm-smmu: Fix MSM8998 clocks description
iommu/vt-d: Remove unused extern declaration dmar_parse_dev_scope()
iommu/vt-d: Fix to convert mm pfn to dma pfn
iommu/vt-d: Fix to flush cache of PASID directory table
iommu/vt-d: Remove rmrr check in domain attaching device path
iommu: Prevent RESV_DIRECT devices from blocking domains
dmaengine/idxd: Re-enable kernel workqueue under DMA API
iommu/vt-d: Add set_dev_pasid callback for dma domain
iommu/vt-d: Prepare for set_dev_pasid callback
iommu/vt-d: Make prq draining code generic
iommu/vt-d: Remove pasid_mutex
iommu/vt-d: Add domain_flush_pasid_iotlb()
iommu: Move global PASID allocation from SVA to core
iommu: Generalize PASID 0 for normal DMA w/o PASID
...
For the case that VT-d page is smaller than mm page, converting dma pfn
should be handled in two cases which are for start pfn and for end pfn.
Currently the calculation of end dma pfn is incorrect and the result is
less than real page frame number which is causing the mapping of iova
always misses some page frames.
Rename the mm_to_dma_pfn() to mm_to_dma_pfn_start() and add a new helper
for converting end dma pfn named mm_to_dma_pfn_end().
Signed-off-by: Yanfei Xu <yanfei.xu@intel.com>
Link: https://lore.kernel.org/r/20230625082046.979742-1-yanfei.xu@intel.com
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
The domain_flush_pasid_iotlb() helper function is used to flush the IOTLB
entries for a given PASID. Previously, this function assumed that
RID2PASID was only used for the first-level DMA translation. However, with
the introduction of the set_dev_pasid callback, this assumption is no
longer valid.
Add a check before using the RID2PASID for PASID invalidation. This check
ensures that the domain has been attached to a physical device before
using RID2PASID.
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20230802212427.1497170-7-jacob.jun.pan@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
The VT-d spec requires to use PASID-based-IOTLB invalidation descriptor
to invalidate IOTLB and the paging-structure caches for a first-stage
page table. Add a generic helper to do this.
RID2PASID is used if the domain has been attached to a physical device,
otherwise real PASIDs that the domain has been attached to will be used.
The 'real' PASID attachment is handled in the subsequent change.
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20230802212427.1497170-4-jacob.jun.pan@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
PCIe Process address space ID (PASID) is used to tag DMA traffic, it
provides finer grained isolation than requester ID (RID).
For each device/RID, 0 is a special PASID for the normal DMA (no
PASID). This is universal across all architectures that supports PASID,
therefore warranted to be reserved globally and declared in the common
header. Consequently, we can avoid the conflict between different PASID
use cases in the generic code. e.g. SVA and DMA API with PASIDs.
This paved away for device drivers to choose global PASID policy while
continue doing normal DMA.
Noting that VT-d could support none-zero RID/NO_PASID, but currently not
used.
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Link: https://lore.kernel.org/r/20230802212427.1497170-2-jacob.jun.pan@linux.intel.com
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
This is a step toward making __iommu_probe_device() self contained.
It should, under proper locking, check if the device is already associated
with an iommu driver and resolve parallel probes. All but one of the
callers open code this test using two different means, but they all
rely on dev->iommu_group.
Currently the bus_iommu_probe()/probe_iommu_group() and
probe_acpi_namespace_devices() rejects already probed devices with an
unlocked read of dev->iommu_group. The OF and ACPI "replay" functions use
device_iommu_mapped() which is the same read without the pointless
refcount.
Move this test into __iommu_probe_device() and put it under the
iommu_probe_device_lock. The store to dev->iommu_group is in
iommu_group_add_device() which is also called under this lock for iommu
driver devices, making it properly locked.
The only path that didn't have this check is the hotplug path triggered by
BUS_NOTIFY_ADD_DEVICE. The only way to get dev->iommu_group assigned
outside the probe path is via iommu_group_add_device(). Today the only
caller is VFIO no-iommu which never associates with an iommu driver. Thus
adding this additional check is safe.
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/1-v3-328044aa278c+45e49-iommu_probe_jgg@nvidia.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
These lines of code were commented out when they were first added in commit
ba39592764 ("Intel IOMMU: Intel IOMMU driver"). We do not want to restore
them because the VT-d spec has deprecated the read/write draining hit.
VT-d spec (section 11.4.2):
"
Hardware implementation with Major Version 2 or higher (VER_REG), always
performs required drain without software explicitly requesting a drain in
IOTLB invalidation. This field is deprecated and hardware will always
report it as 1 to maintain backward compatibility with software.
"
Remove the code to make the code cleaner.
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Link: https://lore.kernel.org/r/20230609060514.15154-1-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Remove the WARN_ON(did == 0) as the domain id 0 is reserved and
set once the domain_ids is allocated. So iommu_init_domains will
never return 0.
Remove the WARN_ON(!table) as this pointer will be accessed in
the following code, if empty "table" really happens, the kernel
will report a NULL pointer reference warning at the first place.
Signed-off-by: Yanfei Xu <yanfei.xu@intel.com>
Link: https://lore.kernel.org/r/20230605112659.308981-3-yanfei.xu@intel.com
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Supervisor Request Enable (SRE) bit in a PASID entry is for permission
checking on DMA requests. When SRE = 0, DMA with supervisor privilege
will be blocked. However, for in-kernel DMA this is not necessary in that
we are targeting kernel memory anyway. There's no need to differentiate
user and kernel for in-kernel DMA.
Let's use non-privileged (user) permission for all PASIDs used in kernel,
it will be consistent with DMA without PASID (RID_PASID) as well.
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Link: https://lore.kernel.org/r/20230331231137.1947675-2-jacob.jun.pan@linux.intel.com
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Generally enabling IOMMU_DEV_FEAT_SVA requires IOMMU_DEV_FEAT_IOPF, but
some devices manage I/O Page Faults themselves instead of relying on the
IOMMU. Move IOPF related code from SVA to IOPF enabling path.
For the device drivers that relies on the IOMMU for IOPF through PCI/PRI,
IOMMU_DEV_FEAT_IOPF must be enabled before and disabled after
IOMMU_DEV_FEAT_SVA.
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20230324120234.313643-4-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Currently enabling SVA requires IOPF support from the IOMMU and device
PCI PRI. However, some devices can handle IOPF by itself without ever
sending PCI page requests nor advertising PRI capability.
Allow SVA support with IOPF handled either by IOMMU (PCI PRI) or device
driver (device-specific IOPF). As long as IOPF could be handled, SVA
should continue to work.
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20230324120234.313643-3-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Pull iommufd updates from Jason Gunthorpe:
"Some polishing and small fixes for iommufd:
- Remove IOMMU_CAP_INTR_REMAP, instead rely on the interrupt
subsystem
- Use GFP_KERNEL_ACCOUNT inside the iommu_domains
- Support VFIO_NOIOMMU mode with iommufd
- Various typos
- A list corruption bug if HWPTs are used for attach"
* tag 'for-linus-iommufd' of git://git.kernel.org/pub/scm/linux/kernel/git/jgg/iommufd:
iommufd: Do not add the same hwpt to the ioas->hwpt_list twice
iommufd: Make sure to zero vfio_iommu_type1_info before copying to user
vfio: Support VFIO_NOIOMMU with iommufd
iommufd: Add three missing structures in ucmd_buffer
selftests: iommu: Fix test_cmd_destroy_access() call in user_copy
iommu: Remove IOMMU_CAP_INTR_REMAP
irq/s390: Add arch_is_isolated_msi() for s390
iommu/x86: Replace IOMMU_CAP_INTR_REMAP with IRQ_DOMAIN_FLAG_ISOLATED_MSI
genirq/msi: Rename IRQ_DOMAIN_MSI_REMAP to IRQ_DOMAIN_ISOLATED_MSI
genirq/irqdomain: Remove unused irq_domain_check_msi_remap() code
iommufd: Convert to msi_device_has_isolated_msi()
vfio/type1: Convert to iommu_group_has_isolated_msi()
iommu: Add iommu_group_has_isolated_msi()
genirq/msi: Add msi_device_has_isolated_msi()
Commit 29b3283972 ("iommu/vt-d: Do not use flush-queue when caching-mode
is on") forced default domains to be strict mode as long as IOMMU
caching-mode is flagged. The reason for doing this is that when vIOMMU
uses VT-d caching mode to synchronize shadowing page tables, the strict
mode shows better performance.
However, this optimization is orthogonal to the first-level page table
because the Intel VT-d architecture does not define the caching mode of
the first-level page table. Refer to VT-d spec, section 6.1, "When the
CM field is reported as Set, any software updates to remapping
structures other than first-stage mapping (including updates to not-
present entries or present entries whose programming resulted in
translation faults) requires explicit invalidation of the caches."
Exclude the first-level page table from this optimization.
Generally using first-stage translation in vIOMMU implies nested
translation enabled in the physical IOMMU. In this case the first-stage
page table is wholly captured by the guest. The vIOMMU only needs to
transfer the cache invalidations on vIOMMU to the physical IOMMU.
Forcing the default domain to strict mode will cause more frequent
cache invalidations, resulting in performance degradation. In a real
performance benchmark test measured by iperf receive, the performance
result on Sapphire Rapids 100Gb NIC shows:
w/ this fix ~51 Gbits/s, w/o this fix ~39.3 Gbits/s.
Theoretically a first-stage IOMMU page table can still be shadowed
in absence of the caching mode, e.g. with host write-protecting guest
IOMMU page table to synchronize changed PTEs with the physical
IOMMU page table. In this case the shadowing overhead is decoupled
from emulating IOTLB invalidation then the overhead of the latter part
is solely decided by the frequency of IOTLB invalidations. Hence
allowing guest default dma domain to be lazy can also benefit the
overall performance by reducing the total VM-exit numbers.
Fixes: 29b3283972 ("iommu/vt-d: Do not use flush-queue when caching-mode is on")
Reported-by: Sanjay Kumar <sanjay.k.kumar@intel.com>
Suggested-by: Sanjay Kumar <sanjay.k.kumar@intel.com>
Signed-off-by: Tina Zhang <tina.zhang@intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20230214025618.2292889-1-tina.zhang@intel.com
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
The Enhanced Command Register is to submit command and operand of
enhanced commands to DMA Remapping hardware. It can supports up to 256
enhanced commands.
There is a HW register to indicate the availability of all 256 enhanced
commands. Each bit stands for each command. But there isn't an existing
interface to read/write all 256 bits. Introduce the u64 ecmdcap[4] to
store the existence of each enhanced command. Read 4 times to get all of
them in map_iommu().
Add a helper to facilitate an enhanced command launch. Make sure hardware
complete the command. Also add a helper to facilitate the check of PMU
essentials. These helpers will be used later.
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Link: https://lore.kernel.org/r/20230128200428.1459118-4-kan.liang@linux.intel.com
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Jason Gunthorpe says:
====================
iommufd follows the same design as KVM and uses memory cgroups to limit
the amount of kernel memory a iommufd file descriptor can pin down. The
various internal data structures already use GFP_KERNEL_ACCOUNT to charge
its own memory.
However, one of the biggest consumers of kernel memory is the IOPTEs
stored under the iommu_domain and these allocations are not tracked.
This series is the first step in fixing it.
The iommu driver contract already includes a 'gfp' argument to the
map_pages op, allowing iommufd to specify GFP_KERNEL_ACCOUNT and then
having the driver allocate the IOPTE tables with that flag will capture a
significant amount of the allocations.
Update the iommu_map() API to pass in the GFP argument, and fix all call
sites. Replace iommu_map_atomic().
Audit the "enterprise" iommu drivers to make sure they do the right thing.
Intel and S390 ignore the GFP argument and always use GFP_ATOMIC. This is
problematic for iommufd anyhow, so fix it. AMD and ARM SMMUv2/3 are
already correct.
A follow up series will be needed to capture the allocations made when the
iommu_domain itself is allocated, which will complete the job.
====================
* 'iommu-memory-accounting' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/joro/iommu:
iommu/s390: Use GFP_KERNEL in sleepable contexts
iommu/s390: Push the gfp parameter to the kmem_cache_alloc()'s
iommu/intel: Use GFP_KERNEL in sleepable contexts
iommu/intel: Support the gfp argument to the map_pages op
iommu/intel: Add a gfp parameter to alloc_pgtable_page()
iommufd: Use GFP_KERNEL_ACCOUNT for iommu_map()
iommu/dma: Use the gfp parameter in __iommu_dma_alloc_noncontiguous()
iommu: Add a gfp parameter to iommu_map_sg()
iommu: Remove iommu_map_atomic()
iommu: Add a gfp parameter to iommu_map()
Link: https://lore.kernel.org/linux-iommu/0-v3-76b587fe28df+6e3-iommu_map_gfp_jgg@nvidia.com
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
On x86 platforms when the HW can support interrupt remapping the iommu
driver creates an irq_domain for the IR hardware and creates a child MSI
irq_domain.
When the global irq_remapping_enabled is set, the IR MSI domain is
assigned to the PCI devices (by intel_irq_remap_add_device(), or
amd_iommu_set_pci_msi_domain()) making those devices have the isolated MSI
property.
Due to how interrupt domains work, setting IRQ_DOMAIN_FLAG_ISOLATED_MSI on
the parent IR domain will cause all struct devices attached to it to
return true from msi_device_has_isolated_msi(). This replaces the
IOMMU_CAP_INTR_REMAP flag as all places using IOMMU_CAP_INTR_REMAP also
call msi_device_has_isolated_msi()
Set the flag and delete the cap.
Link: https://lore.kernel.org/r/7-v3-3313bb5dd3a3+10f11-secure_msi_jgg@nvidia.com
Tested-by: Matthew Rosato <mjrosato@linux.ibm.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Pull iommu updates from Joerg Roedel:
"Core code:
- map/unmap_pages() cleanup
- SVA and IOPF refactoring
- Clean up and document return codes from device/domain attachment
AMD driver:
- Rework and extend parsing code for ivrs_ioapic, ivrs_hpet and
ivrs_acpihid command line options
- Some smaller cleanups
Intel driver:
- Blocking domain support
- Cleanups
S390 driver:
- Fixes and improvements for attach and aperture handling
PAMU driver:
- Resource leak fix and cleanup
Rockchip driver:
- Page table permission bit fix
Mediatek driver:
- Improve safety from invalid dts input
- Smaller fixes and improvements
Exynos driver:
- Fix driver initialization sequence
Sun50i driver:
- Remove IOMMU_DOMAIN_IDENTITY as it has not been working forever
- Various other fixes"
* tag 'iommu-updates-v6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu: (74 commits)
iommu/mediatek: Fix forever loop in error handling
iommu/mediatek: Fix crash on isr after kexec()
iommu/sun50i: Remove IOMMU_DOMAIN_IDENTITY
iommu/amd: Fix typo in macro parameter name
iommu/mediatek: Remove unused "mapping" member from mtk_iommu_data
iommu/mediatek: Improve safety for mediatek,smi property in larb nodes
iommu/mediatek: Validate number of phandles associated with "mediatek,larbs"
iommu/mediatek: Add error path for loop of mm_dts_parse
iommu/mediatek: Use component_match_add
iommu/mediatek: Add platform_device_put for recovering the device refcnt
iommu/fsl_pamu: Fix resource leak in fsl_pamu_probe()
iommu/vt-d: Use real field for indication of first level
iommu/vt-d: Remove unnecessary domain_context_mapped()
iommu/vt-d: Rename domain_add_dev_info()
iommu/vt-d: Rename iommu_disable_dev_iotlb()
iommu/vt-d: Add blocking domain support
iommu/vt-d: Add device_block_translation() helper
iommu/vt-d: Allocate pasid table in device probe path
iommu/amd: Check return value of mmu_notifier_register()
iommu/amd: Fix pci device refcount leak in ppr_notifier()
...
Pull iommufd implementation from Jason Gunthorpe:
"iommufd is the user API to control the IOMMU subsystem as it relates
to managing IO page tables that point at user space memory.
It takes over from drivers/vfio/vfio_iommu_type1.c (aka the VFIO
container) which is the VFIO specific interface for a similar idea.
We see a broad need for extended features, some being highly IOMMU
device specific:
- Binding iommu_domain's to PASID/SSID
- Userspace IO page tables, for ARM, x86 and S390
- Kernel bypassed invalidation of user page tables
- Re-use of the KVM page table in the IOMMU
- Dirty page tracking in the IOMMU
- Runtime Increase/Decrease of IOPTE size
- PRI support with faults resolved in userspace
Many of these HW features exist to support VM use cases - for instance
the combination of PASID, PRI and Userspace IO Page Tables allows an
implementation of DMA Shared Virtual Addressing (vSVA) within a guest.
Dirty tracking enables VM live migration with SRIOV devices and PASID
support allow creating "scalable IOV" devices, among other things.
As these features are fundamental to a VM platform they need to be
uniformly exposed to all the driver families that do DMA into VMs,
which is currently VFIO and VDPA"
For more background, see the extended explanations in Jason's pull request:
https://lore.kernel.org/lkml/Y5dzTU8dlmXTbzoJ@nvidia.com/
* tag 'for-linus-iommufd' of git://git.kernel.org/pub/scm/linux/kernel/git/jgg/iommufd: (62 commits)
iommufd: Change the order of MSI setup
iommufd: Improve a few unclear bits of code
iommufd: Fix comment typos
vfio: Move vfio group specific code into group.c
vfio: Refactor dma APIs for emulated devices
vfio: Wrap vfio group module init/clean code into helpers
vfio: Refactor vfio_device open and close
vfio: Make vfio_device_open() truly device specific
vfio: Swap order of vfio_device_container_register() and open_device()
vfio: Set device->group in helper function
vfio: Create wrappers for group register/unregister
vfio: Move the sanity check of the group to vfio_create_group()
vfio: Simplify vfio_create_group()
iommufd: Allow iommufd to supply /dev/vfio/vfio
vfio: Make vfio_container optionally compiled
vfio: Move container related MODULE_ALIAS statements into container.c
vfio-iommufd: Support iommufd for emulated VFIO devices
vfio-iommufd: Support iommufd for physical VFIO devices
vfio-iommufd: Allow iommufd to be used in place of a container fd
vfio: Use IOMMU_CAP_ENFORCE_CACHE_COHERENCY for vfio_file_enforced_coherent()
...
