linux-kernel - [PATCH v4 0/6] powerpc: pSeries: vfio: iommu: Re-enable support for SPAPR TCE VFIO

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Date: Mon, 24 Jun 2024 12:38:07 +0000
From: Shivaprasad G Bhat <sbhat@...ux.ibm.com>
To: mpe@...erman.id.au, tpearson@...torengineering.com,
        alex.williamson@...hat.com, linuxppc-dev@...ts.ozlabs.org, aik@....com
Cc: npiggin@...il.com, christophe.leroy@...roup.eu, aneesh.kumar@...nel.org,
        naveen.n.rao@...ux.ibm.com, gbatra@...ux.vnet.ibm.com,
        brking@...ux.vnet.ibm.com, sbhat@...ux.ibm.com, aik@...abs.ru,
        jgg@...pe.ca, ruscur@...sell.cc, robh@...nel.org,
        sanastasio@...torengineering.com, linux-kernel@...r.kernel.org,
        joel@....id.au, kvm@...r.kernel.org, msuchanek@...e.de,
        oohall@...il.com, mahesh@...ux.ibm.com, jroedel@...e.de,
        vaibhav@...ux.ibm.com, svaidy@...ux.ibm.com
Subject: [PATCH v4 0/6] powerpc: pSeries: vfio: iommu: Re-enable support for
 SPAPR TCE VFIO

The patches reimplement the iommu table_group_ops for pSeries
for VFIO SPAPR TCE sub-driver thereby bringing consistency with
PowerNV implementation and getting rid of limitations/bugs which
were emanating from these differences on the earlier approach on
pSeries.

Structure of the patchset:
-------------------------
The first and fifth patches just code movements.

Second patch takes care of collecting the TCE and DDW information
for the vfio_iommu_spapr_tce_ddw_info during probe.

Third patch fixes the convention of using table[1] for VFs on
pSeries when used by the host driver.

Fourth patch fixes the VFIO to call TCE clear before unset window.

The last patch has the API reimplementations, please find the
details on its commit description.

Testing:
-------
Tested with nested guest for NVME card, Mellanox multi-function
card by attaching them to nested kvm guest running on a pSeries
lpar.
Also vfio-test [2] by Alex Willamson, was forked and updated to
add support for pSeries guest and used to test these patches[3].

Limitations/Known Issues:
------------------------
* The DMA window restrictions with SRIOV VF scenarios of having
maximum 1 dma window is taken care in the current patches itself.
However, the necessary changes required in
vfio_iommu_spapr_tce_ddw_info to expose the default window being
a 64-bit one and the qemu changes handle the same will be taken
care in future versions.

References:
----------
[1] https://lore.kernel.org/linuxppc-dev/171026724548.8367.8321359354119254395.stgit@linux.ibm.com/
[2] https://github.com/awilliam/tests
[3] https://github.com/nnmwebmin/vfio-ppc-tests/tree/vfio-ppc-ex

---
Changelog:
v3: https://lore.kernel.org/linuxppc-dev/171810893836.1721.2640631616827396553.stgit@linux.ibm.com/
 - Rebased to top of the tree.
 - In the first patch, spapr_tce_table_group_ops is only used locally in
   the pseries/iommu.c file. So, made it static.
 - Fixed the test robot reported issues 202406121640.yr6LK5HJ-lkp@...el.com
   and 202406142110.r97Ts8Xm-lkp@...el.com
 - Updated the commit messages

v2: https://lore.kernel.org/linuxppc-dev/171450753489.10851.3056035705169121613.stgit@linux.ibm.com/
 - Rebased to upstream. So, required the explicit vmalloc.h inclusion as its
   removed from the system header io.h now.
 - Fixed the DLPAR hotplugged device assignment case. The dma window
   property is backed up before removal. That copy is restored when required.
 - Cleaned up bit more. Removed leftover debug prints and dump_stack()s.
 - The warning at remap_pfn_range_notrack() during kvm guest boot is no longer
   seen after the rebase.

v1: https://lore.kernel.org/linuxppc-dev/171026724548.8367.8321359354119254395.stgit@linux.ibm.com/
 - Rewrite as to stop borrowing the DMA windows and implemented
 the table_group_ops for pSeries.
 - Cover letter and Patch 6 has more details as this was a rewrite.

Shivaprasad G Bhat (6):
      powerpc/iommu: Move pSeries specific functions to pseries/iommu.c
      powerpc/pseries/iommu: Fix the VFIO_IOMMU_SPAPR_TCE_GET_INFO ioctl output
      powerpc/pseries/iommu: Use the iommu table[0] for IOV VF's DDW
      vfio/spapr: Always clear TCEs before unsetting the window
      powerpc/iommu: Move dev_has_iommu_table() to iommu.c
      powerpc/iommu: Reimplement the iommu_table_group_ops for pSeries


 arch/powerpc/include/asm/iommu.h          |  14 +-
 arch/powerpc/kernel/eeh.c                 |  16 -
 arch/powerpc/kernel/iommu.c               | 170 +-----
 arch/powerpc/platforms/powernv/pci-ioda.c |   6 +-
 arch/powerpc/platforms/pseries/iommu.c    | 704 +++++++++++++++++++++-
 drivers/vfio/vfio_iommu_spapr_tce.c       |  13 +-
 6 files changed, 718 insertions(+), 205 deletions(-)

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