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linux-next/Documentation/arm64/silicon-errata.txt
Linus Torvalds fb4e3beeff IOMMU Updates for Linux v4.13
This update comes with:
 
 	* Support for lockless operation in the ARM io-pgtable code.
 	  This is an important step to solve the scalability problems in
 	  the common dma-iommu code for ARM
 
 	* Some Errata workarounds for ARM SMMU implemenations
 
 	* Rewrite of the deferred IO/TLB flush code in the AMD IOMMU
 	  driver. The code suffered from very high flush rates, with the
 	  new implementation the flush rate is down to ~1% of what it
 	  was before
 
 	* Support for amd_iommu=off when booting with kexec. Problem
 	  here was that the IOMMU driver bailed out early without
 	  disabling the iommu hardware, if it was enabled in the old
 	  kernel
 
 	* The Rockchip IOMMU driver is now available on ARM64
 
 	* Align the return value of the iommu_ops->device_group
 	  call-backs to not miss error values
 
 	* Preempt-disable optimizations in the Intel VT-d and common
 	  IOVA code to help Linux-RT
 
 	* Various other small cleanups and fixes
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Merge tag 'iommu-updates-v4.13' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu

Pull IOMMU updates from Joerg Roedel:
 "This update comes with:

   - Support for lockless operation in the ARM io-pgtable code.

     This is an important step to solve the scalability problems in the
     common dma-iommu code for ARM

   - Some Errata workarounds for ARM SMMU implemenations

   - Rewrite of the deferred IO/TLB flush code in the AMD IOMMU driver.

     The code suffered from very high flush rates, with the new
     implementation the flush rate is down to ~1% of what it was before

   - Support for amd_iommu=off when booting with kexec.

     The problem here was that the IOMMU driver bailed out early without
     disabling the iommu hardware, if it was enabled in the old kernel

   - The Rockchip IOMMU driver is now available on ARM64

   - Align the return value of the iommu_ops->device_group call-backs to
     not miss error values

   - Preempt-disable optimizations in the Intel VT-d and common IOVA
     code to help Linux-RT

   - Various other small cleanups and fixes"

* tag 'iommu-updates-v4.13' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu: (60 commits)
  iommu/vt-d: Constify intel_dma_ops
  iommu: Warn once when device_group callback returns NULL
  iommu/omap: Return ERR_PTR in device_group call-back
  iommu: Return ERR_PTR() values from device_group call-backs
  iommu/s390: Use iommu_group_get_for_dev() in s390_iommu_add_device()
  iommu/vt-d: Don't disable preemption while accessing deferred_flush()
  iommu/iova: Don't disable preempt around this_cpu_ptr()
  iommu/arm-smmu-v3: Add workaround for Cavium ThunderX2 erratum #126
  iommu/arm-smmu-v3: Enable ACPI based HiSilicon CMD_PREFETCH quirk(erratum 161010701)
  iommu/arm-smmu-v3: Add workaround for Cavium ThunderX2 erratum #74
  ACPI/IORT: Fixup SMMUv3 resource size for Cavium ThunderX2 SMMUv3 model
  iommu/arm-smmu-v3, acpi: Add temporary Cavium SMMU-V3 IORT model number definitions
  iommu/io-pgtable-arm: Use dma_wmb() instead of wmb() when publishing table
  iommu/io-pgtable: depend on !GENERIC_ATOMIC64 when using COMPILE_TEST with LPAE
  iommu/arm-smmu-v3: Remove io-pgtable spinlock
  iommu/arm-smmu: Remove io-pgtable spinlock
  iommu/io-pgtable-arm-v7s: Support lockless operation
  iommu/io-pgtable-arm: Support lockless operation
  iommu/io-pgtable: Introduce explicit coherency
  iommu/io-pgtable-arm-v7s: Refactor split_blk_unmap
  ...
2017-07-12 10:00:04 -07:00

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Silicon Errata and Software Workarounds
=======================================
Author: Will Deacon <will.deacon@arm.com>
Date : 27 November 2015
It is an unfortunate fact of life that hardware is often produced with
so-called "errata", which can cause it to deviate from the architecture
under specific circumstances. For hardware produced by ARM, these
errata are broadly classified into the following categories:
Category A: A critical error without a viable workaround.
Category B: A significant or critical error with an acceptable
workaround.
Category C: A minor error that is not expected to occur under normal
operation.
For more information, consult one of the "Software Developers Errata
Notice" documents available on infocenter.arm.com (registration
required).
As far as Linux is concerned, Category B errata may require some special
treatment in the operating system. For example, avoiding a particular
sequence of code, or configuring the processor in a particular way. A
less common situation may require similar actions in order to declassify
a Category A erratum into a Category C erratum. These are collectively
known as "software workarounds" and are only required in the minority of
cases (e.g. those cases that both require a non-secure workaround *and*
can be triggered by Linux).
For software workarounds that may adversely impact systems unaffected by
the erratum in question, a Kconfig entry is added under "Kernel
Features" -> "ARM errata workarounds via the alternatives framework".
These are enabled by default and patched in at runtime when an affected
CPU is detected. For less-intrusive workarounds, a Kconfig option is not
available and the code is structured (preferably with a comment) in such
a way that the erratum will not be hit.
This approach can make it slightly onerous to determine exactly which
errata are worked around in an arbitrary kernel source tree, so this
file acts as a registry of software workarounds in the Linux Kernel and
will be updated when new workarounds are committed and backported to
stable kernels.
| Implementor | Component | Erratum ID | Kconfig |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A53 | #826319 | ARM64_ERRATUM_826319 |
| ARM | Cortex-A53 | #827319 | ARM64_ERRATUM_827319 |
| ARM | Cortex-A53 | #824069 | ARM64_ERRATUM_824069 |
| ARM | Cortex-A53 | #819472 | ARM64_ERRATUM_819472 |
| ARM | Cortex-A53 | #845719 | ARM64_ERRATUM_845719 |
| ARM | Cortex-A53 | #843419 | ARM64_ERRATUM_843419 |
| ARM | Cortex-A57 | #832075 | ARM64_ERRATUM_832075 |
| ARM | Cortex-A57 | #852523 | N/A |
| ARM | Cortex-A57 | #834220 | ARM64_ERRATUM_834220 |
| ARM | Cortex-A72 | #853709 | N/A |
| ARM | Cortex-A73 | #858921 | ARM64_ERRATUM_858921 |
| ARM | MMU-500 | #841119,#826419 | N/A |
| | | | |
| Cavium | ThunderX ITS | #22375, #24313 | CAVIUM_ERRATUM_22375 |
| Cavium | ThunderX ITS | #23144 | CAVIUM_ERRATUM_23144 |
| Cavium | ThunderX GICv3 | #23154 | CAVIUM_ERRATUM_23154 |
| Cavium | ThunderX Core | #27456 | CAVIUM_ERRATUM_27456 |
| Cavium | ThunderX Core | #30115 | CAVIUM_ERRATUM_30115 |
| Cavium | ThunderX SMMUv2 | #27704 | N/A |
| Cavium | ThunderX2 SMMUv3| #74 | N/A |
| Cavium | ThunderX2 SMMUv3| #126 | N/A |
| | | | |
| Freescale/NXP | LS2080A/LS1043A | A-008585 | FSL_ERRATUM_A008585 |
| | | | |
| Hisilicon | Hip0{5,6,7} | #161010101 | HISILICON_ERRATUM_161010101 |
| Hisilicon | Hip0{6,7} | #161010701 | N/A |
| | | | |
| Qualcomm Tech. | Falkor v1 | E1003 | QCOM_FALKOR_ERRATUM_1003 |
| Qualcomm Tech. | Falkor v1 | E1009 | QCOM_FALKOR_ERRATUM_1009 |
| Qualcomm Tech. | QDF2400 ITS | E0065 | QCOM_QDF2400_ERRATUM_0065 |