s390/pci: use unique UIDs for domain enumeration

Use UIDs as domain numbers if the UID checking rules apply (in this
case the FW guarantees uniqueness of these values).
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/pci_clp.h

@@ -46,6 +46,8 @@ struct clp_fh_list_entry {
 #define CLP_UTIL_STR_LEN	64
 #define CLP_PFIP_NR_SEGMENTS	4
 
+extern bool zpci_unique_uid;
+
 /* List PCI functions request */
 struct clp_req_list_pci {
 	struct clp_req_hdr hdr;
@@ -59,7 +61,8 @@ struct clp_rsp_list_pci {
 	u64 resume_token;
 	u32 reserved2;
 	u16 max_fn;
-	u8 reserved3;
+	u8			: 7;
+	u8 uid_checking		: 1;
 	u8 entry_size;
 	struct clp_fh_list_entry fh_list[CLP_FH_LIST_NR_ENTRIES];
 } __packed;

arch/s390/pci/pci.c

@@ -722,6 +722,11 @@ struct dev_pm_ops pcibios_pm_ops = {
 
 static int zpci_alloc_domain(struct zpci_dev *zdev)
 {
+	if (zpci_unique_uid) {
+		zdev->domain = (u16) zdev->uid;
+		return 0;
+	}
+
 	spin_lock(&zpci_domain_lock);
 	zdev->domain = find_first_zero_bit(zpci_domain, ZPCI_NR_DEVICES);
 	if (zdev->domain == ZPCI_NR_DEVICES) {
@@ -735,6 +740,9 @@ static int zpci_alloc_domain(struct zpci_dev *zdev)
 
 static void zpci_free_domain(struct zpci_dev *zdev)
 {
+	if (zpci_unique_uid)
+		return;
+
 	spin_lock(&zpci_domain_lock);
 	clear_bit(zdev->domain, zpci_domain);
 	spin_unlock(&zpci_domain_lock);

arch/s390/pci/pci_clp.c

@@ -22,6 +22,8 @@
 #include <asm/clp.h>
 #include <uapi/asm/clp.h>
 
+bool zpci_unique_uid;
+
 static inline void zpci_err_clp(unsigned int rsp, int rc)
 {
 	struct {
@@ -315,6 +317,7 @@ static int clp_list_pci(struct clp_req_rsp_list_pci *rrb,
 			goto out;
 		}
 
+		zpci_unique_uid = rrb->response.uid_checking;
 		WARN_ON_ONCE(rrb->response.entry_size !=
 			sizeof(struct clp_fh_list_entry));