[SRU][B][PATCH 1/2] s390/pci: Recover handle in clp_set_pci_fn()

[frank.heimes at canonical.com]

From: Niklas Schnelle <schnelle at linux.ibm.com>

BugLink: https://bugs.launchpad.net/bugs/1870320

When we try to recover a PCI function using

    echo 1 > /sys/bus/pci/devices/<id>/recover

or manually with

    echo 1 > /sys/bus/pci/devices/<id>/remove
    echo 0 > /sys/bus/pci/slots/<slot>/power
    echo 1 > /sys/bus/pci/slots/<slot>/power

clp_disable_fn() / clp_enable_fn() call clp_set_pci_fn() to first
disable and then reenable the function.

When the function is already in the requested state we may be left with
an invalid function handle.

To get a new valid handle we do a clp_list_pci() call. For this we need
both the function ID and function handle in clp_set_pci_fn() so pass the
zdev and get both.

To simplify things also pull setting the refreshed function handle into
clp_set_pci_fn()

Signed-off-by: Niklas Schnelle <schnelle at linux.ibm.com>
Reviewed-by: Peter Oberparleiter <oberpar at linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor at linux.ibm.com>
(backported from commit 17cdec960cf776b20b1fb08c622221babe591d51)
Signed-off-by: Frank Heimes <frank.heimes at canonical.com>

---
 arch/s390/include/asm/pci.h |  2 +-
 arch/s390/pci/pci.c         |  2 +-
 arch/s390/pci/pci_clp.c     | 46 ++++++++++++++++++++-----------------
 3 files changed, 27 insertions(+), 23 deletions(-)

diff --git a/arch/s390/include/asm/pci.h b/arch/s390/include/asm/pci.h
index 12fe3591034f..c1dc76d5a1f8 100644
--- a/arch/s390/include/asm/pci.h
+++ b/arch/s390/include/asm/pci.h
@@ -172,7 +172,7 @@ void zpci_remove_reserved_devices(void);
 /* CLP */
 int clp_scan_pci_devices(void);
 int clp_rescan_pci_devices(void);
-int clp_rescan_pci_devices_simple(void);
+int clp_rescan_pci_devices_simple(u32 *fid);
 int clp_add_pci_device(u32, u32, int);
 int clp_enable_fh(struct zpci_dev *, u8);
 int clp_disable_fh(struct zpci_dev *);
diff --git a/arch/s390/pci/pci.c b/arch/s390/pci/pci.c
index 8a505cfdd9b9..d402ff52b26c 100644
--- a/arch/s390/pci/pci.c
+++ b/arch/s390/pci/pci.c
@@ -1002,5 +1002,5 @@ subsys_initcall_sync(pci_base_init);
 void zpci_rescan(void)
 {
 	if (zpci_is_enabled())
-		clp_rescan_pci_devices_simple();
+		clp_rescan_pci_devices_simple(NULL);
 }
diff --git a/arch/s390/pci/pci_clp.c b/arch/s390/pci/pci_clp.c
index d8dfd645bf02..1c3ddcf27fab 100644
--- a/arch/s390/pci/pci_clp.c
+++ b/arch/s390/pci/pci_clp.c
@@ -234,12 +234,14 @@ int clp_add_pci_device(u32 fid, u32 fh, int configured)
 }
 
 /*
- * Enable/Disable a given PCI function defined by its function handle.
+ * Enable/Disable a given PCI function and update its function handle if
+ * necessary
  */
-static int clp_set_pci_fn(u32 *fh, u8 nr_dma_as, u8 command)
+static int clp_set_pci_fn(struct zpci_dev *zdev, u8 nr_dma_as, u8 command)
 {
 	struct clp_req_rsp_set_pci *rrb;
 	int rc, retries = 100;
+	u32 fid = zdev->fid;
 
 	rrb = clp_alloc_block(GFP_KERNEL);
 	if (!rrb)
@@ -250,7 +252,7 @@ static int clp_set_pci_fn(u32 *fh, u8 nr_dma_as, u8 command)
 		rrb->request.hdr.len = sizeof(rrb->request);
 		rrb->request.hdr.cmd = CLP_SET_PCI_FN;
 		rrb->response.hdr.len = sizeof(rrb->response);
-		rrb->request.fh = *fh;
+		rrb->request.fh = zdev->fh;
 		rrb->request.oc = command;
 		rrb->request.ndas = nr_dma_as;
 
@@ -263,12 +265,17 @@ static int clp_set_pci_fn(u32 *fh, u8 nr_dma_as, u8 command)
 		}
 	} while (rrb->response.hdr.rsp == CLP_RC_SETPCIFN_BUSY);
 
-	if (!rc && rrb->response.hdr.rsp == CLP_RC_OK)
-		*fh = rrb->response.fh;
-	else {
+	if (rc || rrb->response.hdr.rsp != CLP_RC_OK) {
 		zpci_err("Set PCI FN:\n");
 		zpci_err_clp(rrb->response.hdr.rsp, rc);
-		rc = -EIO;
+	}
+
+	if (!rc && rrb->response.hdr.rsp == CLP_RC_OK) {
+		zdev->fh = rrb->response.fh;
+	} else if (!rc && rrb->response.hdr.rsp == CLP_RC_SETPCIFN_ALRDY &&
+			rrb->response.fh == 0) {
+		/* Function is already in desired state - update handle */
+		rc = clp_rescan_pci_devices_simple(&fid);
 	}
 	clp_free_block(rrb);
 	return rc;
@@ -276,31 +283,21 @@ static int clp_set_pci_fn(u32 *fh, u8 nr_dma_as, u8 command)
 
 int clp_enable_fh(struct zpci_dev *zdev, u8 nr_dma_as)
 {
-	u32 fh = zdev->fh;
 	int rc;
 
-	rc = clp_set_pci_fn(&fh, nr_dma_as, CLP_SET_ENABLE_PCI_FN);
-	if (!rc)
-		/* Success -> store enabled handle in zdev */
-		zdev->fh = fh;
-
+	rc = clp_set_pci_fn(zdev, nr_dma_as, CLP_SET_ENABLE_PCI_FN);
 	zpci_dbg(3, "ena fid:%x, fh:%x, rc:%d\n", zdev->fid, zdev->fh, rc);
 	return rc;
 }
 
 int clp_disable_fh(struct zpci_dev *zdev)
 {
-	u32 fh = zdev->fh;
 	int rc;
 
 	if (!zdev_enabled(zdev))
 		return 0;
 
-	rc = clp_set_pci_fn(&fh, 0, CLP_SET_DISABLE_PCI_FN);
-	if (!rc)
-		/* Success -> store disabled handle in zdev */
-		zdev->fh = fh;
-
+	rc = clp_set_pci_fn(zdev, 0, CLP_SET_DISABLE_PCI_FN);
 	zpci_dbg(3, "dis fid:%x, fh:%x, rc:%d\n", zdev->fid, zdev->fh, rc);
 	return rc;
 }
@@ -358,10 +355,14 @@ static void __clp_add(struct clp_fh_list_entry *entry, void *data)
 static void __clp_update(struct clp_fh_list_entry *entry, void *data)
 {
 	struct zpci_dev *zdev;
+	u32 *fid = data;
 
 	if (!entry->vendor_id)
 		return;
 
+	if (fid && *fid != entry->fid)
+		return;
+
 	zdev = get_zdev_by_fid(entry->fid);
 	if (!zdev)
 		return;
@@ -401,7 +402,10 @@ int clp_rescan_pci_devices(void)
 	return rc;
 }
 
-int clp_rescan_pci_devices_simple(void)
+/* Rescan PCI functions and refresh function handles. If fid is non-NULL only
+ * refresh the handle of the function matching @fid
+ */
+int clp_rescan_pci_devices_simple(u32 *fid)
 {
 	struct clp_req_rsp_list_pci *rrb;
 	int rc;
@@ -410,7 +414,7 @@ int clp_rescan_pci_devices_simple(void)
 	if (!rrb)
 		return -ENOMEM;
 
-	rc = clp_list_pci(rrb, NULL, __clp_update);
+	rc = clp_list_pci(rrb, fid, __clp_update);
 
 	clp_free_block(rrb);
 	return rc;
-- 
2.25.1