linux/drivers/iommu
Jean-Philippe Brucker edcc40d2ab iommu: Remove iommu_sva_ops::mm_exit()
After binding a device to an mm, device drivers currently need to
register a mm_exit handler. This function is called when the mm exits,
to gracefully stop DMA targeting the address space and flush page faults
to the IOMMU.

This is deemed too complex for the MMU release() notifier, which may be
triggered by any mmput() invocation, from about 120 callsites [1]. The
upcoming SVA module has an example of such complexity: the I/O Page
Fault handler would need to call mmput_async() instead of mmput() after
handling an IOPF, to avoid triggering the release() notifier which would
in turn drain the IOPF queue and lock up.

Another concern is the DMA stop function taking too long, up to several
minutes [2]. For some mmput() callers this may disturb other users. For
example, if the OOM killer picks the mm bound to a device as the victim
and that mm's memory is locked, if the release() takes too long, it
might choose additional innocent victims to kill.

To simplify the MMU release notifier, don't forward the notification to
device drivers. Since they don't stop DMA on mm exit anymore, the PASID
lifetime is extended:

(1) The device driver calls bind(). A PASID is allocated.

  Here any DMA fault is handled by mm, and on error we don't print
  anything to dmesg. Userspace can easily trigger errors by issuing DMA
  on unmapped buffers.

(2) exit_mmap(), for example the process took a SIGKILL. This step
    doesn't happen during normal operations. Remove the pgd from the
    PASID table, since the page tables are about to be freed. Invalidate
    the IOTLBs.

  Here the device may still perform DMA on the address space. Incoming
  transactions are aborted but faults aren't printed out. ATS
  Translation Requests return Successful Translation Completions with
  R=W=0. PRI Page Requests return with Invalid Request.

(3) The device driver stops DMA, possibly following release of a fd, and
    calls unbind(). PASID table is cleared, IOTLB invalidated if
    necessary. The page fault queues are drained, and the PASID is
    freed.

  If DMA for that PASID is still running here, something went seriously
  wrong and errors should be reported.

For now remove iommu_sva_ops entirely. We might need to re-introduce
them at some point, for example to notify device drivers of unhandled
IOPF.

[1] https://lore.kernel.org/linux-iommu/20200306174239.GM31668@ziepe.ca/
[2] https://lore.kernel.org/linux-iommu/4d68da96-0ad5-b412-5987-2f7a6aa796c3@amd.com/

Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Acked-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Acked-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20200423125329.782066-3-jean-philippe@linaro.org
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2020-05-29 14:52:53 +02:00
..
amd_iommu_debugfs.c iommu/amd: Add basic debugfs infrastructure for AMD IOMMU 2018-07-06 14:06:30 +02:00
amd_iommu_init.c iommu/amd: Fix legacy interrupt remapping for x2APIC-enabled system 2020-05-01 13:21:18 +02:00
amd_iommu_proto.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 333 2019-06-05 17:37:06 +02:00
amd_iommu_quirks.c iommu/amd: Apply the same IVRS IOAPIC workaround to Acer Aspire A315-41 2019-10-30 10:24:03 +01:00
amd_iommu_types.h iommu/amd: Remove dev_data->passthrough 2020-05-05 14:36:13 +02:00
amd_iommu_v2.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 333 2019-06-05 17:37:06 +02:00
amd_iommu.c iommu/amd: Use pci_ats_supported() 2020-05-27 14:35:41 +02:00
amd_iommu.h iommu/amd: Override wrong IVRS IOAPIC on Raven Ridge systems 2019-08-23 10:26:48 +02:00
arm-smmu-impl.c iommu/arm-smmu: Rename public #defines under ARM_SMMU_ namespace 2020-01-10 15:52:25 +00:00
arm-smmu-qcom.c iommu: arm-smmu-impl: Add sdm845 implementation hook 2019-11-04 17:48:37 +00:00
arm-smmu-v3.c iommu/arm-smmu-v3: Use pci_ats_supported() 2020-05-27 14:35:41 +02:00
arm-smmu.c iommu/arm-smmu: Convert to probe/release_device() call-backs 2020-05-05 14:36:13 +02:00
arm-smmu.h iommu/io-pgtable-arm: Rationalise VTCR handling 2020-01-10 15:52:25 +00:00
dma-iommu.c iommu/dma: Fix MSI reservation allocation 2020-03-04 16:27:56 +01:00
dmar.c iommu/vt-d: Ignore devices with out-of-spec domain number 2020-03-14 09:38:39 +01:00
exynos-iommu.c iommu/exynos: Convert to probe/release_device() call-backs 2020-05-05 14:36:14 +02:00
fsl_pamu_domain.c iommu/pamu: Convert to probe/release_device() call-backs 2020-05-05 14:36:13 +02:00
fsl_pamu_domain.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 266 2019-06-05 17:30:28 +02:00
fsl_pamu.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 266 2019-06-05 17:30:28 +02:00
fsl_pamu.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 266 2019-06-05 17:30:28 +02:00
hyperv-iommu.c iommu/hyper-v: Add Hyper-V stub IOMMU driver 2019-02-28 11:12:16 +01:00
intel_irq_remapping.c iommu/vt-d: Fix wrong analysis whether devices share the same bus 2019-08-30 15:47:37 +02:00
intel-iommu-debugfs.c iommu/vt-d: Populate debugfs if IOMMUs are detected 2020-03-14 20:02:43 +01:00
intel-iommu.c iommu/vt-d: Use pci_ats_supported() 2020-05-27 14:35:41 +02:00
intel-pasid.c iommu/vt-d: Add PASID_FLAG_FL5LP for first-level pasid setup 2020-01-07 14:05:58 +01:00
intel-pasid.h iommu/vt-d: Add PASID_FLAG_FL5LP for first-level pasid setup 2020-01-07 14:05:58 +01:00
intel-svm.c Merge branches 'iommu/fixes', 'arm/qcom', 'arm/omap', 'arm/smmu', 'x86/amd', 'x86/vt-d', 'virtio' and 'core' into next 2020-03-27 11:33:27 +01:00
intel-trace.c iommu/vt-d: Add trace events for device dma map/unmap 2019-09-11 12:34:30 +02:00
io-pgtable-arm-v7s.c iommu/io-pgtable-arm: Rationalise TCR handling 2020-01-10 15:52:24 +00:00
io-pgtable-arm.c iommu/io-pgtable-arm: Fix IOVA validation for 32-bit 2020-03-02 17:17:26 +01:00
io-pgtable.c iommu/io-pgtable-arm: Rationalise TCR handling 2020-01-10 15:52:24 +00:00
ioasid.c iommu/ioasid: Add custom allocators 2019-10-15 13:34:25 +02:00
iommu-debugfs.c iommu: Fix IOMMU debugfs fallout 2019-02-26 11:15:58 +01:00
iommu-sysfs.c drivers/iommu: Export core IOMMU API symbols to permit modular drivers 2019-12-23 14:06:05 +01:00
iommu-traces.c
iommu.c iommu: Remove iommu_sva_ops::mm_exit() 2020-05-29 14:52:53 +02:00
iova.c iommu/iova: Unify format of the printed messages 2020-05-13 10:54:51 +02:00
ipmmu-vmsa.c iommu/renesas: Fix unused-function warning 2020-05-13 10:46:56 +02:00
irq_remapping.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
irq_remapping.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 333 2019-06-05 17:37:06 +02:00
Kconfig iommu: spapr_tce: Disable compile testing to fix build on book3s_32 config 2020-04-29 13:55:40 +02:00
Makefile iommu/arm-smmu: Restore naming of driver parameter prefix 2020-02-19 12:03:21 +01:00
msm_iommu_hw-8xxx.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 267 2019-06-05 17:30:29 +02:00
msm_iommu.c iommu/msm: Convert to probe/release_device() call-backs 2020-05-05 14:36:13 +02:00
msm_iommu.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 267 2019-06-05 17:30:29 +02:00
mtk_iommu_v1.c iommu/mediatek-v1: Fix a build warning for a unused variable 'data' 2020-05-19 14:18:38 +02:00
mtk_iommu.c iommu/mediatek: Convert to probe/release_device() call-backs 2020-05-05 14:36:13 +02:00
mtk_iommu.h iommu/mediatek: Move the tlb_sync into tlb_flush 2019-11-11 15:02:34 +01:00
of_iommu.c iommu/arm-smmu-v3: Parse PASID devicetree property of platform devices 2020-01-15 16:00:57 +00:00
omap-iommu-debug.c Merge branches 'x86/vt-d', 'x86/amd', 'arm/smmu', 'arm/omap', 'generic-dma-ops' and 'core' into next 2019-07-04 17:26:48 +02:00
omap-iommu.c iommu/omap: Add registration for DT fwnode pointer 2020-05-18 15:39:45 +02:00
omap-iommu.h iommu/omap: add support for late attachment of iommu devices 2019-08-09 17:37:10 +02:00
omap-iopgtable.h iommu/omap: Fix -Woverflow warnings when compiling on 64-bit architectures 2020-03-04 16:24:46 +01:00
qcom_iommu.c Linux 5.7-rc4 2020-05-13 12:01:33 +02:00
rockchip-iommu.c iommu/rockchip: Convert to probe/release_device() call-backs 2020-05-05 14:36:13 +02:00
s390-iommu.c iommu/s390: Convert to probe/release_device() call-backs 2020-05-05 14:36:13 +02:00
tegra-gart.c iommu/tegra: Convert to probe/release_device() call-backs 2020-05-05 14:36:14 +02:00
tegra-smmu.c iommu/tegra: Convert to probe/release_device() call-backs 2020-05-05 14:36:14 +02:00
virtio-iommu.c iommu/virtio: Convert to probe/release_device() call-backs 2020-05-05 14:36:13 +02:00