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From: Damien Le Moal <damien.lemoal@opensource.wdc.com>
To: Bjorn Helgaas <bhelgaas@google.com>, linux-pci@vger.kernel.org
Cc: Niklas Cassel <niklas.cassel@wdc.com>
Subject: [PATCH] pci: Avoid FLR for AMD FCH AHCI adapters
Date: Sat, 28 Jan 2023 10:39:51 +0900	[thread overview]
Message-ID: <20230128013951.523247-1-damien.lemoal@opensource.wdc.com> (raw)

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

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

gives a working guest OS, thus indicating that the default flr reset
method is defective, resulting in the adapter not being reset correctly.

This patch applies the no_flr quirk to AMD FCH AHCI devices to
permanently solve this issue.

Reported-by: Niklas Cassel <niklas.cassel@wdc.com>
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
---
 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);
 
-- 
2.39.1


             reply	other threads:[~2023-01-28  1:39 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-28  1:39 Damien Le Moal [this message]
2023-01-30 15:21 ` [PATCH] pci: Avoid FLR for AMD FCH AHCI adapters Bjorn Helgaas
2023-01-30 15:46   ` Niklas Cassel
2023-01-30 16:04     ` Bjorn Helgaas
2023-01-31  0:36       ` Damien Le Moal
2023-01-30 16:12   ` Shyam Sundar S K
2023-01-30 16:33     ` Niklas Cassel

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