PCI: Fix pci_enable_acs() support for the ACS quirks

JIRA: https://issues.redhat.com/browse/RHEL-67693
Upstream Status: f3c3ccc

commit f3c3ccc
Author: Jason Gunthorpe <[email protected]>
Date:   Wed Oct 16 20:52:33 2024 -0300

    PCI: Fix pci_enable_acs() support for the ACS quirks

    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/[email protected]
    Fixes: 47c8846 ("PCI: Extend ACS configurability")
    Reported-by: Jiri Slaby <[email protected]>
    Closes: https://lore.kernel.org/all/[email protected]
    Closes: https://bugzilla.suse.com/show_bug.cgi?id=1229019
    Tested-by: Steffen Dirkwinkel <[email protected]>
    Signed-off-by: Jason Gunthorpe <[email protected]>
    Signed-off-by: Bjorn Helgaas <[email protected]>

Signed-off-by: Myron Stowe <[email protected]>

Author: Myron Stowe

drivers/pci/pci.c

@@ -1067,8 +1067,15 @@ 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;
@@ -1077,11 +1084,8 @@ 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.