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When using 128-bit interrupt-remapping table entry (IRTE) (a.k.a GA mode),
current driver disables interrupt remapping when it updates the IRTE
so that the upper and lower 64-bit values can be updated safely.
However, this creates a small window, where the interrupt could
arrive and result in IO_PAGE_FAULT (for interrupt) as shown below.
IOMMU Driver Device IRQ
============ ===========
irte.RemapEn=0
...
change IRTE IRQ from device ==> IO_PAGE_FAULT !!
...
irte.RemapEn=1
This scenario has been observed when changing irq affinity on a system
running I/O-intensive workload, in which the destination APIC ID
in the IRTE is updated.
Instead, use cmpxchg_double() to update the 128-bit IRTE at once without
disabling the interrupt remapping. However, this means several features,
which require GA (128-bit IRTE) support will also be affected if cmpxchg16b
is not supported (which is unprecedented for AMD processors w/ IOMMU).
Fixes: 880ac60e25 ("iommu/amd: Introduce interrupt remapping ops structure")
Reported-by: Sean Osborne <sean.m.osborne@oracle.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Tested-by: Erik Rockstrom <erik.rockstrom@oracle.com>
Reviewed-by: Joao Martins <joao.m.martins@oracle.com>
Link: https://lore.kernel.org/r/20200903093822.52012-3-suravee.suthikulpanit@amd.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
45 lines
1.5 KiB
Plaintext
45 lines
1.5 KiB
Plaintext
# SPDX-License-Identifier: GPL-2.0-only
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# AMD IOMMU support
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config AMD_IOMMU
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bool "AMD IOMMU support"
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select SWIOTLB
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select PCI_MSI
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select PCI_ATS
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select PCI_PRI
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select PCI_PASID
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select IOMMU_API
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select IOMMU_IOVA
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select IOMMU_DMA
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depends on X86_64 && PCI && ACPI && HAVE_CMPXCHG_DOUBLE
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help
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With this option you can enable support for AMD IOMMU hardware in
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your system. An IOMMU is a hardware component which provides
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remapping of DMA memory accesses from devices. With an AMD IOMMU you
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can isolate the DMA memory of different devices and protect the
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system from misbehaving device drivers or hardware.
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You can find out if your system has an AMD IOMMU if you look into
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your BIOS for an option to enable it or if you have an IVRS ACPI
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table.
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config AMD_IOMMU_V2
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tristate "AMD IOMMU Version 2 driver"
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depends on AMD_IOMMU
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select MMU_NOTIFIER
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help
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This option enables support for the AMD IOMMUv2 features of the IOMMU
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hardware. Select this option if you want to use devices that support
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the PCI PRI and PASID interface.
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config AMD_IOMMU_DEBUGFS
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bool "Enable AMD IOMMU internals in DebugFS"
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depends on AMD_IOMMU && IOMMU_DEBUGFS
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help
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!!!WARNING!!! !!!WARNING!!! !!!WARNING!!! !!!WARNING!!!
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DO NOT ENABLE THIS OPTION UNLESS YOU REALLY, -REALLY- KNOW WHAT YOU ARE DOING!!!
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Exposes AMD IOMMU device internals in DebugFS.
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This option is -NOT- intended for production environments, and should
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not generally be enabled.
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