[SRU][N:gcp][PATCH 105/109] PCI: Fix pci_enable_acs() support for the ACS quirks

[Tim Whisonant]

From: Jason Gunthorpe <jgg at nvidia.com>

BugLink: https://bugs.launchpad.net/bugs/2111859

There are ACS quirks that hijack the normal ACS processing and deliver to
to special quirk code. The enable path needs to call
pci_dev_specific_enable_acs() and then pci_dev_specific_acs_enabled() will
report the hidden ACS state controlled by the quirk.

The recent rework got this out of order and we should try to call
pci_dev_specific_enable_acs() regardless of any actual ACS support in the
device.

As before command line parameters that effect standard PCI ACS don't
interact with the quirk versions, including the new config_acs= option.

Link: https://lore.kernel.org/r/0-v1-f96b686c625b+124-pci_acs_quirk_fix_jgg@nvidia.com
Fixes: 47c8846a49ba ("PCI: Extend ACS configurability")
Reported-by: Jiri Slaby <jirislaby at kernel.org>
Closes: https://lore.kernel.org/all/e89107da-ac99-4d3a-9527-a4df9986e120@kernel.org
Closes: https://bugzilla.suse.com/show_bug.cgi?id=1229019
Tested-by: Steffen Dirkwinkel <me at steffen.cc>
Signed-off-by: Jason Gunthorpe <jgg at nvidia.com>
Signed-off-by: Bjorn Helgaas <bhelgaas at google.com>
(cherry picked from commit f3c3ccc4fe49dbc560b01d16bebd1b116c46c2b4)
Signed-off-by: Tim Whisonant <tim.whisonant at canonical.com>
---
 drivers/pci/pci.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index cf6db97ce0dc..bbfdf92f7797 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1076,8 +1076,15 @@ static void pci_std_enable_acs(struct pci_dev *dev, struct pci_acs *caps)
 static void pci_enable_acs(struct pci_dev *dev)
 {
 	struct pci_acs caps;
+	bool enable_acs = false;
 	int pos;
 
+	/* If an iommu is present we start with kernel default caps */
+	if (pci_acs_enable) {
+		if (pci_dev_specific_enable_acs(dev))
+			enable_acs = true;
+	}
+
 	pos = dev->acs_cap;
 	if (!pos)
 		return;
@@ -1086,11 +1093,8 @@ static void pci_enable_acs(struct pci_dev *dev)
 	pci_read_config_word(dev, pos + PCI_ACS_CTRL, &caps.ctrl);
 	caps.fw_ctrl = caps.ctrl;
 
-	/* If an iommu is present we start with kernel default caps */
-	if (pci_acs_enable) {
-		if (pci_dev_specific_enable_acs(dev))
-			pci_std_enable_acs(dev, &caps);
-	}
+	if (enable_acs)
+		pci_std_enable_acs(dev, &caps);
 
 	/*
 	 * Always apply caps from the command line, even if there is no iommu.
-- 
2.43.0