PCI: Avoid FLR for AMD FCH AHCI adapters

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/[email protected]
Reported-by: Niklas Cassel <[email protected]>
Signed-off-by: Damien Le Moal <[email protected]>
Signed-off-by: Bjorn Helgaas <[email protected]>
Cc: [email protected]

0 files changed, 0 insertions, 0 deletions