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Commit aa39330a authored by Damien Le Moal's avatar Damien Le Moal Committed by Greg Kroah-Hartman
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PCI: Avoid FLR for AMD FCH AHCI adapters

commit 63ba51db24ed1b8f8088a897290eb6c036c5435d upstream.

PCI passthrough to VMs does not work with AMD FCH AHCI adapters: the guest
OS fails to correctly probe devices attached to the controller due to FIS
communication failures:

  ata4: softreset failed (1st FIS failed)
  ...
  ata4.00: qc timeout after 5000 msecs (cmd 0xec)
  ata4.00: failed to IDENTIFY (I/O error, err_mask=0x4)

Forcing the "bus" reset method before unbinding & binding the adapter to
the vfio-pci driver solves this issue, e.g.:

  echo "bus" > /sys/bus/pci/devices/<ID>/reset_method

gives a working guest OS, indicating that the default FLR reset method
doesn't work correctly.

Apply quirk_no_flr() to AMD FCH AHCI devices to work around this issue.

Link: https://lore.kernel.org/r/20230128013951.523247-1-damien.lemoal@opensource.wdc.com


Reported-by: default avatarNiklas Cassel <niklas.cassel@wdc.com>
Signed-off-by: default avatarDamien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 87e47be3
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