From: Niklas Schnelle <schnelle@linux.ibm.com>
Date: Thu, 22 Jul 2021 11:44:08 +0200
Subject: s390/pci: simplify CLP List PCI handling
Git-commit: cc049eecfb7adc4bfecd05eb25e425d8def96fce
Patch-mainline: v5.15-rc1
References: jsc#PED-592

Currently clp_get_state() and clp_refresh_fh() awkwardly use the
clp_list_pci() callback mechanism to find the entry for a specific FID
and update its zdev, respectively return its state.

This is both needlessly complex and means we are always going through
the entire PCI function list even if the FID has already been found.
Instead lets introduce a clp_find_pci() function to find a specific
entry and share the CLP List PCI request handling code with
clp_list_pci().

With that in place we can also easily make the function handle a simple
out parameter instead of directly altering the zdev allowing easier
access to the updated function handle by the caller.

Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 arch/s390/include/asm/pci.h |    6 -
 arch/s390/pci/pci.c         |   28 ++++---
 arch/s390/pci/pci_clp.c     |  155 +++++++++++++++++++++++---------------------
 3 files changed, 102 insertions(+), 87 deletions(-)

--- a/arch/s390/include/asm/pci.h
+++ b/arch/s390/include/asm/pci.h
@@ -216,10 +216,10 @@ void zpci_remove_reserved_devices(void);
 int clp_setup_writeback_mio(void);
 int clp_scan_pci_devices(void);
 int clp_query_pci_fn(struct zpci_dev *zdev);
-int clp_enable_fh(struct zpci_dev *, u8);
-int clp_disable_fh(struct zpci_dev *);
+int clp_enable_fh(struct zpci_dev *zdev, u32 *fh, u8 nr_dma_as);
+int clp_disable_fh(struct zpci_dev *zdev, u32 *fh);
 int clp_get_state(u32 fid, enum zpci_state *state);
-int clp_refresh_fh(u32 fid);
+int clp_refresh_fh(u32 fid, u32 *fh);
 
 /* UID */
 void update_uid_checking(bool new);
--- a/arch/s390/pci/pci.c
+++ b/arch/s390/pci/pci.c
@@ -659,12 +659,14 @@ void zpci_free_domain(int domain)
 
 int zpci_enable_device(struct zpci_dev *zdev)
 {
+	u32 fh = zdev->fh;
 	int rc;
 
-	if (clp_enable_fh(zdev, ZPCI_NR_DMA_SPACES)) {
+	if (clp_enable_fh(zdev, &fh, ZPCI_NR_DMA_SPACES)) {
 		rc = -EIO;
 		goto out;
 	}
+	zdev->fh = fh;
 
 	rc = zpci_dma_init_device(zdev);
 	if (rc)
@@ -673,29 +675,33 @@ int zpci_enable_device(struct zpci_dev *
 	return 0;
 
 out_dma:
-	clp_disable_fh(zdev);
+	clp_disable_fh(zdev, &fh);
 out:
+	zdev->fh = fh;
 	return rc;
 }
 
 int zpci_disable_device(struct zpci_dev *zdev)
 {
+	u32 fh = zdev->fh;
 	int cc, rc = 0;
 
 	zpci_dma_exit_device(zdev);
-	/*
-	 * The zPCI function may already be disabled by the platform, this is
-	 * detected in clp_disable_fh() which becomes a no-op.
-	 */
-	cc = clp_disable_fh(zdev);
-	if (cc == CLP_RC_SETPCIFN_ALRDY) {
+	if (!zdev_enabled(zdev))
+		return 0;
+	cc = clp_disable_fh(zdev, &fh);
+	if (!cc) {
+		zdev->fh = fh;
+	} else if (cc == CLP_RC_SETPCIFN_ALRDY) {
 		pr_info("Disabling PCI function %08x had no effect as it was already disabled\n",
 			zdev->fid);
 		/* Function is already disabled - update handle */
-		rc = clp_refresh_fh(zdev->fid);
-		if (!rc)
+		rc = clp_refresh_fh(zdev->fid, &fh);
+		if (!rc) {
+			zdev->fh = fh;
 			rc = -EINVAL;
-	} else if (cc) {
+		}
+	} else {
 		rc = -EIO;
 	}
 	return rc;
--- a/arch/s390/pci/pci_clp.c
+++ b/arch/s390/pci/pci_clp.c
@@ -215,17 +215,19 @@ out:
 /**
  * clp_set_pci_fn() - Execute a command on a PCI function
  * @zdev: Function that will be affected
+ * @fh: Out parameter for updated function handle
  * @nr_dma_as: DMA address space number
  * @command: The command code to execute
  *
  * Returns: 0 on success, < 0 for Linux errors (e.g. -ENOMEM), and
  * > 0 for non-success platform responses
  */
-static int clp_set_pci_fn(struct zpci_dev *zdev, u8 nr_dma_as, u8 command)
+static int clp_set_pci_fn(struct zpci_dev *zdev, u32 *fh, u8 nr_dma_as, u8 command)
 {
 	struct clp_req_rsp_set_pci *rrb;
 	int rc, retries = 100;
 
+	*fh = 0;
 	rrb = clp_alloc_block(GFP_KERNEL);
 	if (!rrb)
 		return -ENOMEM;
@@ -249,7 +251,7 @@ static int clp_set_pci_fn(struct zpci_de
 	} while (rrb->response.hdr.rsp == CLP_RC_SETPCIFN_BUSY);
 
 	if (!rc && rrb->response.hdr.rsp == CLP_RC_OK) {
-		zdev->fh = rrb->response.fh;
+		*fh = rrb->response.fh;
 	} else {
 		zpci_err("Set PCI FN:\n");
 		zpci_err_clp(rrb->response.hdr.rsp, rc);
@@ -294,31 +296,62 @@ int clp_setup_writeback_mio(void)
 	return rc;
 }
 
-int clp_enable_fh(struct zpci_dev *zdev, u8 nr_dma_as)
+int clp_enable_fh(struct zpci_dev *zdev, u32 *fh, u8 nr_dma_as)
 {
 	int rc;
 
-	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);
+	rc = clp_set_pci_fn(zdev, fh, nr_dma_as, CLP_SET_ENABLE_PCI_FN);
+	zpci_dbg(3, "ena fid:%x, fh:%x, rc:%d\n", zdev->fid, *fh, rc);
 	if (!rc && zpci_use_mio(zdev)) {
-		rc = clp_set_pci_fn(zdev, nr_dma_as, CLP_SET_ENABLE_MIO);
+		rc = clp_set_pci_fn(zdev, fh, nr_dma_as, CLP_SET_ENABLE_MIO);
 		zpci_dbg(3, "ena mio fid:%x, fh:%x, rc:%d\n",
-				zdev->fid, zdev->fh, rc);
+				zdev->fid, *fh, rc);
 		if (rc)
-			clp_disable_fh(zdev);
+			clp_disable_fh(zdev, fh);
 	}
 	return rc;
 }
 
-int clp_disable_fh(struct zpci_dev *zdev)
+int clp_disable_fh(struct zpci_dev *zdev, u32 *fh)
 {
 	int rc;
 
 	if (!zdev_enabled(zdev))
 		return 0;
 
-	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);
+	rc = clp_set_pci_fn(zdev, fh, 0, CLP_SET_DISABLE_PCI_FN);
+	zpci_dbg(3, "dis fid:%x, fh:%x, rc:%d\n", zdev->fid, *fh, rc);
+	return rc;
+}
+
+static int clp_list_pci_req(struct clp_req_rsp_list_pci *rrb,
+			    u64 *resume_token, int *nentries)
+{
+	int rc;
+
+	memset(rrb, 0, sizeof(*rrb));
+	rrb->request.hdr.len = sizeof(rrb->request);
+	rrb->request.hdr.cmd = CLP_LIST_PCI;
+	/* store as many entries as possible */
+	rrb->response.hdr.len = CLP_BLK_SIZE - LIST_PCI_HDR_LEN;
+	rrb->request.resume_token = *resume_token;
+
+	/* Get PCI function handle list */
+	rc = clp_req(rrb, CLP_LPS_PCI);
+	if (rc || rrb->response.hdr.rsp != CLP_RC_OK) {
+		zpci_err("List PCI FN:\n");
+		zpci_err_clp(rrb->response.hdr.rsp, rc);
+		return -EIO;
+	}
+
+	update_uid_checking(rrb->response.uid_checking);
+	WARN_ON_ONCE(rrb->response.entry_size !=
+		sizeof(struct clp_fh_list_entry));
+
+	*nentries = (rrb->response.hdr.len - LIST_PCI_HDR_LEN) /
+		rrb->response.entry_size;
+	*resume_token = rrb->response.resume_token;
+
 	return rc;
 }
 
@@ -326,38 +359,40 @@ static int clp_list_pci(struct clp_req_r
 			void (*cb)(struct clp_fh_list_entry *, void *))
 {
 	u64 resume_token = 0;
-	int entries, i, rc;
+	int nentries, i, rc;
 
 	do {
-		memset(rrb, 0, sizeof(*rrb));
-		rrb->request.hdr.len = sizeof(rrb->request);
-		rrb->request.hdr.cmd = CLP_LIST_PCI;
-		/* store as many entries as possible */
-		rrb->response.hdr.len = CLP_BLK_SIZE - LIST_PCI_HDR_LEN;
-		rrb->request.resume_token = resume_token;
-
-		/* Get PCI function handle list */
-		rc = clp_req(rrb, CLP_LPS_PCI);
-		if (rc || rrb->response.hdr.rsp != CLP_RC_OK) {
-			zpci_err("List PCI FN:\n");
-			zpci_err_clp(rrb->response.hdr.rsp, rc);
-			rc = -EIO;
-			goto out;
-		}
+		rc = clp_list_pci_req(rrb, &resume_token, &nentries);
+		if (rc)
+			return rc;
+		for (i = 0; i < nentries; i++)
+			cb(&rrb->response.fh_list[i], data);
+	} while (resume_token);
 
-		update_uid_checking(rrb->response.uid_checking);
-		WARN_ON_ONCE(rrb->response.entry_size !=
-			sizeof(struct clp_fh_list_entry));
+	return rc;
+}
 
-		entries = (rrb->response.hdr.len - LIST_PCI_HDR_LEN) /
-			rrb->response.entry_size;
+static int clp_find_pci(struct clp_req_rsp_list_pci *rrb, u32 fid,
+			struct clp_fh_list_entry *entry)
+{
+	struct clp_fh_list_entry *fh_list;
+	u64 resume_token = 0;
+	int nentries, i, rc;
 
-		resume_token = rrb->response.resume_token;
-		for (i = 0; i < entries; i++)
-			cb(&rrb->response.fh_list[i], data);
+	do {
+		rc = clp_list_pci_req(rrb, &resume_token, &nentries);
+		if (rc)
+			return rc;
+		for (i = 0; i < nentries; i++) {
+			fh_list = rrb->response.fh_list;
+			if (fh_list[i].fid == fid) {
+				*entry = fh_list[i];
+				return 0;
+			}
+		}
 	} while (resume_token);
-out:
-	return rc;
+
+	return -ENODEV;
 }
 
 static void __clp_add(struct clp_fh_list_entry *entry, void *data)
@@ -387,67 +422,41 @@ int clp_scan_pci_devices(void)
 	return rc;
 }
 
-static void __clp_refresh_fh(struct clp_fh_list_entry *entry, void *data)
-{
-	struct zpci_dev *zdev;
-	u32 fid = *((u32 *)data);
-
-	if (!entry->vendor_id || fid != entry->fid)
-		return;
-
-	zdev = get_zdev_by_fid(fid);
-	if (!zdev)
-		return;
-
-	zdev->fh = entry->fh;
-}
-
 /*
- * Refresh the function handle of the function matching @fid
+ * Get the current function handle of the function matching @fid
  */
-int clp_refresh_fh(u32 fid)
+int clp_refresh_fh(u32 fid, u32 *fh)
 {
 	struct clp_req_rsp_list_pci *rrb;
+	struct clp_fh_list_entry entry;
 	int rc;
 
 	rrb = clp_alloc_block(GFP_NOWAIT);
 	if (!rrb)
 		return -ENOMEM;
 
-	rc = clp_list_pci(rrb, &fid, __clp_refresh_fh);
+	rc = clp_find_pci(rrb, fid, &entry);
+	if (!rc)
+		*fh = entry.fh;
 
 	clp_free_block(rrb);
 	return rc;
 }
 
-struct clp_state_data {
-	u32 fid;
-	enum zpci_state state;
-};
-
-static void __clp_get_state(struct clp_fh_list_entry *entry, void *data)
-{
-	struct clp_state_data *sd = data;
-
-	if (entry->fid != sd->fid)
-		return;
-
-	sd->state = entry->config_state;
-}
-
 int clp_get_state(u32 fid, enum zpci_state *state)
 {
 	struct clp_req_rsp_list_pci *rrb;
-	struct clp_state_data sd = {fid, ZPCI_FN_STATE_RESERVED};
+	struct clp_fh_list_entry entry;
 	int rc;
 
+	*state = ZPCI_FN_STATE_RESERVED;
 	rrb = clp_alloc_block(GFP_ATOMIC);
 	if (!rrb)
 		return -ENOMEM;
 
-	rc = clp_list_pci(rrb, &sd, __clp_get_state);
+	rc = clp_find_pci(rrb, fid, &entry);
 	if (!rc)
-		*state = sd.state;
+		*state = entry.config_state;
 
 	clp_free_block(rrb);
 	return rc;