linux-kernel - [PATCH v2 0/5] iommu/s390: Further improvements

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Message-Id: <20221109142903.4080275-1-schnelle@linux.ibm.com>
Date:   Wed,  9 Nov 2022 15:28:58 +0100
From:   Niklas Schnelle <schnelle@...ux.ibm.com>
To:     Matthew Rosato <mjrosato@...ux.ibm.com>, iommu@...ts.linux.dev,
        Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Jason Gunthorpe <jgg@...dia.com>
Cc:     Gerd Bayer <gbayer@...ux.ibm.com>,
        Pierre Morel <pmorel@...ux.ibm.com>,
        linux-s390@...r.kernel.org, borntraeger@...ux.ibm.com,
        hca@...ux.ibm.com, gor@...ux.ibm.com,
        gerald.schaefer@...ux.ibm.com, agordeev@...ux.ibm.com,
        svens@...ux.ibm.com, linux-kernel@...r.kernel.org
Subject: [PATCH v2 0/5] iommu/s390: Further improvements

Hi All,

This series of patches improves the s390 IOMMU driver. These improvements help
existing IOMMU users, mainly vfio-pci, but at the same time are also in
preparation of converting s390 to use the common DMA API implementation in
drivers/iommu/dma-iommu.c instead of its platform specific DMA API in
arch/s390/pci/pci_dma.c that sidesteps the IOMMU driver to control the same
hardware interface directly.

Among the included changes patch 1 improves the robustness of switching IOMMU
domains and patch 2 adds the I/O TLB operations necessary for the DMA API
conversion. Patches 3, 4, and 5 aim to improve performance with patch 5 being
the most intrusive by removing the I/O translation table lock and using atomic
updates instead.

This series is based on the s390 branch of Joerg's IOMMU tree[0] that includes
the latest s390 IOMMU fixes. It is available for easy testing in the
iommu_improve_v2 branch with signed tag s390_iommu_improve_v2 of my
git.kernel.org tree[1].

Best regards,
Niklas Schnelle

Changes sinve v1:
- If an IOTLB flush fails for one device don't skip the flush for other devices.
  This is also needed when RCU readers try to flush a detached device. (Jason)
- Free a domain's IOMMU translation table via call_rcu() (Jason)

[0] https://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu.git/log/?h=s390
[1] https://git.kernel.org/pub/scm/linux/kernel/git/niks/linux.git/

Niklas Schnelle (5):
  iommu/s390: Make attach succeed even if the device is in error state
  iommu/s390: Add I/O TLB ops
  iommu/s390: Use RCU to allow concurrent domain_list iteration
  iommu/s390: Optimize IOMMU table walking
  s390/pci: use lock-free I/O translation updates

 arch/s390/include/asm/pci.h |   4 +-
 arch/s390/kvm/pci.c         |   6 +-
 arch/s390/pci/pci.c         |  13 +--
 arch/s390/pci/pci_dma.c     |  77 +++++++++------
 drivers/iommu/s390-iommu.c  | 184 ++++++++++++++++++++++++------------
 5 files changed, 185 insertions(+), 99 deletions(-)

-- 
2.34.1