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/0-v1-f96b686c625b+124-pci_acs_quirk_fix_jgg@nvidia.com
Fixes: 47c8846a49ba ("PCI: Extend ACS configurability")
Reported-by: Jiri Slaby <jirislaby@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@steffen.cc>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 7d85c04fbba2ae937f15f2a5b481e002ce81f334..225a6cd2e9ca3bf9885a1b8a9e4d7ad4b291fc8e 100644 (file)
--- a/drivers/pci/pci.c
+++ b/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.