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e52d58d54a
linux/drivers/iommu/amd
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Suravee Suthikulpanit e52d58d54a iommu/amd: Use cmpxchg_double() when updating 128-bit IRTE 
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>
2020-09-04 11:53:18 +02:00
..
amd_iommu_types.h
amd_iommu.h iommu/amd: Make amd_iommu_apply_ivrs_quirks() static inline 2020-06-30 14:47:42 +02:00
debugfs.c
init.c iommu/amd: Use cmpxchg_double() when updating 128-bit IRTE 2020-09-04 11:53:18 +02:00
iommu_v2.c mm: do page fault accounting in handle_mm_fault 2020-08-12 10:58:02 -07:00
iommu.c iommu/amd: Use cmpxchg_double() when updating 128-bit IRTE 2020-09-04 11:53:18 +02:00
Kconfig iommu/amd: Use cmpxchg_double() when updating 128-bit IRTE 2020-09-04 11:53:18 +02:00
Makefile iommu/amd: Move Kconfig and Makefile bits down into amd directory 2020-07-29 14:15:36 +02:00
quirks.c