[PATCH v4 00/11] iommu/vt-d: Optimize the use of locks

[Lu Baolu <baolu.lu@linux.intel.com>]

Hi folks,

This series tries to optimize the uses of two locks in the Intel IOMMU
driver:

- The intel_iommu::lock is used to protect the IOMMU resources shared by
  devices. They include the IOMMU root and context tables, the pasid
  tables and the domain IDs.
- The global device_domain_lock is used to protect the global and the
  per-domain device tracking lists.

The optimization includes:

- Remove the unnecessary global device tracking list;
- Remove unnecessary locking;
- Reduce the scope of the lock as much as possible, that is, use the
  lock only where necessary;
- The global lock is transformed into a local lock to improve the
  efficiency.

This series is also available on github:
https://github.com/LuBaolu/intel-iommu/commits/intel-iommu-lock-optimization-v4

Your comments and suggestions are very appreciated.

Best regards,
baolu

Change log:

v4:
 - Kevin pointed out that the copy table failure path needs some
   improvements. We agreed that it worth a separated series to handle
   all improvements on copy table.
 - Kevin suggested that we could put all spinlock replacement changes in
   a single patch. Updated in this series.
 - Others look good to Kevin. (Thanks and very appreciated for all the
   review comments.)

v3:
 - https://lore.kernel.org/linux-iommu/20220629074725.2331441-1-baolu.lu@linux.intel.com/
 - Split reduction of lock ranges from changing irqsave.
   https://lore.kernel.org/linux-iommu/BN9PR11MB52760A3D7C6BF1AF9C9D34658CAA9@BN9PR11MB5276.namprd11.prod.outlook.com/
 - Fully initialize the dev_info before adding it to the list.
   https://lore.kernel.org/linux-iommu/BN9PR11MB52764D7CD86448C5E4EB46668CAA9@BN9PR11MB5276.namprd11.prod.outlook.com/
 - Various code and comments refinement.

v2:
 - https://lore.kernel.org/linux-iommu/20220614025137.1632762-1-baolu.lu@linux.intel.com/
 - Split the lock-free page walk issue into a new patch:
   https://lore.kernel.org/linux-iommu/20220609070811.902868-1-baolu.lu@linux.intel.com/
 - Drop the conversion from spinlock to mutex and make this series
   cleanup purpose only.
 - Address several comments received during v1 review.

v1:
 - https://lore.kernel.org/linux-iommu/20220527063019.3112905-1-baolu.lu@linux.intel.com/
 - Initial post.

Lu Baolu (11):
  iommu/vt-d: debugfs: Remove device_domain_lock usage
  iommu/vt-d: Remove clearing translation data in disable_dmar_iommu()
  iommu/vt-d: Use pci_get_domain_bus_and_slot() in pgtable_walk()
  iommu/vt-d: Unnecessary spinlock for root table alloc and free
  iommu/vt-d: Replace spin_lock_irqsave() with spin_lock()
  iommu/vt-d: Acquiring lock in domain ID allocation helpers
  iommu/vt-d: Acquiring lock in pasid manipulation helpers
  iommu/vt-d: Check device list of domain in domain free path
  iommu/vt-d: Fold __dmar_remove_one_dev_info() into its caller
  iommu/vt-d: Use device_domain_lock accurately
  iommu/vt-d: Convert global spinlock into per domain lock

 drivers/iommu/intel/iommu.h   |   3 +-
 drivers/iommu/intel/pasid.h   |   1 +
 drivers/iommu/intel/debugfs.c |  49 ++++---
 drivers/iommu/intel/iommu.c   | 249 ++++++++++------------------------
 drivers/iommu/intel/pasid.c   | 103 +++++++-------
 drivers/iommu/intel/svm.c     |   5 +-
 6 files changed, 163 insertions(+), 247 deletions(-)

-- 
2.25.1