From: Tianyu Lan <>

Traditionally swiotlb was not performance critical because it was only
used for slow devices. But in some setups, like TDX/SEV confidential
guests, all IO has to go through swiotlb. Currently swiotlb only has a
single lock. Under high IO load with multiple CPUs this can lead to
significat lock contention on the swiotlb lock.

Patch 1 is to introduce swiotlb area concept and split up single swiotlb
Patch 2 set swiotlb area number with lapic number

Tianyu Lan (2):
  swiotlb: Split up single swiotlb lock
  x86/ACPI: Set swiotlb area according to the number of lapic entry in

 .../admin-guide/kernel-parameters.txt         |   4 +-
 arch/x86/kernel/acpi/boot.c                   |   3 +
 include/linux/swiotlb.h                       |  27 +++
 kernel/dma/swiotlb.c                          | 202 ++++++++++++++----
 4 files changed, 197 insertions(+), 39 deletions(-)


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