[RFC PATCH v2 0/2] Reduce IOTLB flush when pass-through dGPU devices

[Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>]

From: Suravee Suthikulpanit <ssuthiku@redhat.com>

Currently, when pass-through dGPU to a guest VM, there are thousands
of IOTLB flush commands sent from IOMMU to end-point-device. This cause
performance issue when launching new VMs, and could cause IOTLB invalidate
time-out issue on certain dGPUs.

This can be avoided by adopting the new fast IOTLB flush APIs.

Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Joerg Roedel <jroedel@suse.de>

Changes from V1: (https://lkml.org/lkml/2017/11/17/764)

  * Rebased on top of v4.15-rc5

  * Patch 1/2: Fix iommu_tlb_range_add() size parameter to use unmapped
    instead of len. (per Alex)

  * Patch 1/2: Use a list to keep track unmapped IOVAs for VFIO remote
    unpinning. Although, I am still not sure if using a list is the best
    way to keep track the IOVAs. (per Alex)

  * Patch 2/2: Fix logic due to missing spin unlock. (per Tom)
     
Suravee Suthikulpanit (2):
  vfio/type1: Adopt fast IOTLB flush interface when unmap IOVAs
  iommu/amd: Add support for fast IOTLB flushing

 drivers/iommu/amd_iommu.c       | 73 ++++++++++++++++++++++++++++++++-
 drivers/iommu/amd_iommu_init.c  |  7 ++++
 drivers/iommu/amd_iommu_types.h |  7 ++++
 drivers/vfio/vfio_iommu_type1.c | 89 +++++++++++++++++++++++++++++++++++------
 4 files changed, 163 insertions(+), 13 deletions(-)

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