From 63ba51db24ed1b8f8088a897290eb6c036c5435d Mon Sep 17 00:00:00 2001
From: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Date: Sat, 28 Jan 2023 10:39:51 +0900
Subject: [PATCH] PCI: Avoid FLR for AMD FCH AHCI adapters
Git-commit: 63ba51db24ed1b8f8088a897290eb6c036c5435d
Patch-mainline: v6.3-rc1
References: git-fixes

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: Niklas Cassel <niklas.cassel@wdc.com>
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: stable@vger.kernel.org
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/pci/quirks.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 285acc4aaccc..20ac67d59034 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -5340,6 +5340,7 @@ static void quirk_no_flr(struct pci_dev *dev)
 DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_AMD, 0x1487, quirk_no_flr);
 DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_AMD, 0x148c, quirk_no_flr);
 DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_AMD, 0x149c, quirk_no_flr);
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_AMD, 0x7901, quirk_no_flr);
 DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x1502, quirk_no_flr);
 DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x1503, quirk_no_flr);
 
-- 
2.35.3