Merge: Merge branch 'pci/acs'

MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/6874

```
    - Correct documentation of the 'config_acs=' kernel parameter (Akihiko
      Odaki)
    - Fix bugs in 'pci=config_acs=' kernel command line parameter (Tushar Dave)

    * pci/acs:
      PCI/ACS: Fix 'pci=config_acs=' parameter

JIRA: https://issues.redhat.com/browse/RHEL-72898

Signed-off-by: Myron Stowe <mstowe@redhat.com>
```

Approved-by: Tony Camuso <tcamuso@redhat.com>
Approved-by: Desnes Nunes <desnesn@redhat.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>

Merged-by: Jan Stancek <jstancek@redhat.com>

Author: jstancek

Documentation/admin-guide/kernel-parameters.txt

@@ -4545,7 +4545,7 @@
 				  '1' – force enabled
 				  'x' – unchanged
 				For example,
-				  pci=config_acs=10x
+				  pci=config_acs=10x@pci:0:0
 				would configure all devices that support
 				ACS to enable P2P Request Redirect, disable
 				Translation Blocking, and leave Source

drivers/pci/pci.c

@@ -955,23 +955,27 @@ struct pci_acs {
 };
 
 static void __pci_config_acs(struct pci_dev *dev, struct pci_acs *caps,
-			     const char *p, u16 mask, u16 flags)
+			     const char *p, const u16 acs_mask, const u16 acs_flags)
 {
+	u16 flags = acs_flags;
+	u16 mask = acs_mask;
 	char *delimit;
 	int ret = 0;
 
 	if (!p)
 		return;
 
 	while (*p) {
-		if (!mask) {
+		if (!acs_mask) {
 			/* Check for ACS flags */
 			delimit = strstr(p, "@");
 			if (delimit) {
 				int end;
 				u32 shift = 0;
 
 				end = delimit - p - 1;
+				mask = 0;
+				flags = 0;
 
 				while (end > -1) {
 					if (*(p + end) == '0') {
@@ -1028,10 +1032,14 @@ static void __pci_config_acs(struct pci_dev *dev, struct pci_acs *caps,
 
 	pci_dbg(dev, "ACS mask  = %#06x\n", mask);
 	pci_dbg(dev, "ACS flags = %#06x\n", flags);
+	pci_dbg(dev, "ACS control = %#06x\n", caps->ctrl);
+	pci_dbg(dev, "ACS fw_ctrl = %#06x\n", caps->fw_ctrl);
 
-	/* If mask is 0 then we copy the bit from the firmware setting. */
-	caps->ctrl = (caps->ctrl & ~mask) | (caps->fw_ctrl & mask);
-	caps->ctrl |= flags;
+	/*
+	 * For mask bits that are 0, copy them from the firmware setting
+	 * and apply flags for all the mask bits that are 1.
+	 */
+	caps->ctrl = (caps->fw_ctrl & ~mask) | (flags & mask);
 
 	pci_info(dev, "Configured ACS to %#06x\n", caps->ctrl);
 }