[PATCH 0/1][SRU][G/U/OEM-5.10] Fix disk probing under SATA controller behind VMD

[You-Sheng Yang]

BugLink: https://bugs.launchpad.net/bugs/1894778

[Impact]

When booting with a certain platforms with boot disk attached to SATA
bus behind Intel VMD controller, disk probing may fail with following
error messages left in dmesg:

  [ 6.163286] ata1.00: qc timeout (cmd 0xec)
  [ 6.165630] ata1.00: failed to IDENTIFY (I/O error, err_mask=0x4)

[Fix]

Upstream commit f6b7bb847ca8 ("PCI: vmd: Offset Client VMD MSI-X
vectors") currently in vanilla kernel tree for v5.11.

[Test Case]

Check dmesg/lsblk for disk probe.

For pci MSI address, check lspci output:

  $ lspci -vvnn
  ....
      Capabilities: [80] MSI: Enable+ Count=1/1 maskable- 64bit-
          Address: fee00000  Data: 0000

When it fails, the address is fee00000. And with a patched kernel:

  $ lspci -vvnn
  ....
      Capabilities: [80] MSI: Enable+ Count=1/1 maskable- 64bit-
          Address: fee01000  Data: 0000

[Where problems could occur]

An unpatched kernel will not be able to probe SATA controllers moved
behind VMD when VMD/RAID mode is enabled in BIOS, leaving disks
attached on it completely unusable. With this change, kernel would
then be able to probe them but may also suffer from issues that only
occur under such configuration. However, the worst case is to move away
sata disks from VMD bus as they are currently without this fix, so the
risk here should be justified.

Jon Derrick (1):
  PCI: vmd: Offset Client VMD MSI-X vectors

 drivers/pci/controller/vmd.c | 37 +++++++++++++++++++++++++-----------
 1 file changed, 26 insertions(+), 11 deletions(-)

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2.29.2