[SRU][jammy:linux-azure][PATCH 0/3] Ubuntu 20.04 confidential VM deployments are failing

[John Cabaj]

BugLink: https://bugs.launchpad.net/bugs/2096813

SRU Justification

[Impact]

* 20.04 Azure CVM (with 5.15 kernel) instances are failing to boot with high reproducibility

[Fix]

* Clean reverts of the following commits:
* 8bd834015a5e: "UBUNTU: SAUCE: swiotlb: Split up single swiotlb lock"
* 3db34e258474: "UBUNTU: SAUCE: swiotlb: allocate memory in a cache-friendly way"
* 9e1b646a9cac: "UBUNTU: SAUCE: swiotlb: use bitmap to track free slots"

[Test Plan]

* Compile tested
* Boot tested
* Tested with Azure images, booted successfully 25 consecutive times

[Regression potential]

* Changes isolated, minimal regression risk. Changes were SAUCE patches, so reverting back to upstream functionality.
* Likely small I/O performance hit under heavy I/O, but alleviates system hangs

[Other info]

* SF#00405149

John Cabaj (3):
  Revert "UBUNTU: SAUCE: swiotlb: Split up single swiotlb lock"
  Revert "UBUNTU: SAUCE: swiotlb: allocate memory in a cache-friendly
    way"
  Revert "UBUNTU: SAUCE: swiotlb: use bitmap to track free slots"

 .../admin-guide/kernel-parameters.txt         |   4 +-
 arch/x86/kernel/acpi/boot.c                   |   4 -
 include/linux/swiotlb.h                       |  44 +--
 kernel/dma/swiotlb.c                          | 280 ++++++------------
 4 files changed, 102 insertions(+), 230 deletions(-)

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2.43.0