[dpdk-dev] [PATCH] bus/pci: restricted bus scanning to allowed devices

[Sunil Kumar Kori <skori@marvell.com>]

rte_bus_scan API scans all the available PCI devices irrespective of white
or black listing parameters then further devices are probed based on white
or black listing parameters. So unnecessary CPU cycles are wasted during
rte_pci_scan.

For Octeontx2 platform with core frequency 2.4 Ghz, rte_bus_scan consumes
around 26ms to scan around 90 PCI devices but all may not be used by the
application. So for the application which uses 2 NICs, rte_bus_scan
consumes few microseconds and rest time is saved with this patch.

Patch restricts devices to be scanned as per below mentioned conditions:
 - All devices will be scanned if no parameters are passed.
 - Only white listed devices will be scanned if white list is available.
 - All devices, except black listed, will be scanned if black list is
   available.

Signed-off-by: Sunil Kumar Kori <skori@marvell.com>
---
 drivers/bus/pci/bsd/pci.c    | 18 +++++++++++++++++-
 drivers/bus/pci/linux/pci.c  | 11 +++++++++++
 drivers/bus/pci/pci_common.c |  4 ++--
 drivers/bus/pci/private.h    | 20 ++++++++++++++++++++
 4 files changed, 50 insertions(+), 3 deletions(-)

diff --git a/drivers/bus/pci/bsd/pci.c b/drivers/bus/pci/bsd/pci.c
index ebbfeb13a..58fa7a241 100644
--- a/drivers/bus/pci/bsd/pci.c
+++ b/drivers/bus/pci/bsd/pci.c
@@ -338,6 +338,9 @@ rte_pci_scan(void)
 			.match_buf_len = sizeof(matches),
 			.matches = &matches[0],
 	};
+	struct rte_pci_device dummy_dev;
+
+	memset(&dummy_dev, 0, sizeof(struct rte_pci_device));
 
 	/* for debug purposes, PCI can be disabled */
 	if (!rte_eal_has_pci())
@@ -357,9 +360,22 @@ rte_pci_scan(void)
 			goto error;
 		}
 
-		for (i = 0; i < conf_io.num_matches; i++)
+		for (i = 0; i < conf_io.num_matches; i++) {
+			/* Create dummy pci device to get devargs */
+			dummy_dev.addr.domain = matches[i].pc_sel.pc_domain;
+			dummy_dev.addr.bus = matches[i].pc_sel.pc_bus;
+			dummy_dev.addr.devid = matches[i].pc_sel.pc_dev;
+			dummy_dev.addr.function = matches[i].pc_sel.pc_func;
+			dummy_dev.device.devargs =
+						pci_devargs_lookup(&dummy_dev);
+
+			/* Check that device should be ignored or not  */
+			if (pci_ignore_device(&dummy_dev))
+				continue;
+
 			if (pci_scan_one(fd, &matches[i]) < 0)
 				goto error;
+		}
 
 		dev_count += conf_io.num_matches;
 	} while(conf_io.status == PCI_GETCONF_MORE_DEVS);
diff --git a/drivers/bus/pci/linux/pci.c b/drivers/bus/pci/linux/pci.c
index 740a2cdad..f6335810b 100644
--- a/drivers/bus/pci/linux/pci.c
+++ b/drivers/bus/pci/linux/pci.c
@@ -458,6 +458,9 @@ rte_pci_scan(void)
 	DIR *dir;
 	char dirname[PATH_MAX];
 	struct rte_pci_addr addr;
+	struct rte_pci_device dummy_dev;
+
+	memset(&dummy_dev, 0, sizeof(struct rte_pci_device));
 
 	/* for debug purposes, PCI can be disabled */
 	if (!rte_eal_has_pci())
@@ -482,6 +485,14 @@ rte_pci_scan(void)
 		if (parse_pci_addr_format(e->d_name, sizeof(e->d_name), &addr) != 0)
 			continue;
 
+		/* Create dummy pci device to get devargs */
+		dummy_dev.addr = addr;
+		dummy_dev.device.devargs = pci_devargs_lookup(&dummy_dev);
+
+		/* Check that device should be ignored or not  */
+		if (pci_ignore_device(&dummy_dev))
+			continue;
+
 		snprintf(dirname, sizeof(dirname), "%s/%s",
 				rte_pci_get_sysfs_path(), e->d_name);
 
diff --git a/drivers/bus/pci/pci_common.c b/drivers/bus/pci/pci_common.c
index 3f5542076..ec063e832 100644
--- a/drivers/bus/pci/pci_common.c
+++ b/drivers/bus/pci/pci_common.c
@@ -42,7 +42,7 @@ const char *rte_pci_get_sysfs_path(void)
 	return path;
 }
 
-static struct rte_devargs *pci_devargs_lookup(struct rte_pci_device *dev)
+struct rte_devargs *pci_devargs_lookup(struct rte_pci_device *dev)
 {
 	struct rte_devargs *devargs;
 	struct rte_pci_addr addr;
@@ -589,7 +589,7 @@ pci_dma_unmap(struct rte_device *dev, void *addr, uint64_t iova, size_t len)
 	return -1;
 }
 
-static bool
+bool
 pci_ignore_device(const struct rte_pci_device *dev)
 {
 	struct rte_devargs *devargs = dev->device.devargs;
diff --git a/drivers/bus/pci/private.h b/drivers/bus/pci/private.h
index a205d4d9f..fc47768c6 100644
--- a/drivers/bus/pci/private.h
+++ b/drivers/bus/pci/private.h
@@ -42,6 +42,26 @@ int rte_pci_scan(void);
 void
 pci_name_set(struct rte_pci_device *dev);
 
+/**
+ * Get the devargs of a PCI device.
+ *
+ * @param pci_dev
+ *	PCI device to be validated
+ * @return
+ *	devargs on succes, NULL otherwise
+ */
+struct rte_devargs *pci_devargs_lookup(struct rte_pci_device *pci_dev);
+
+/**
+ * Validate whether a pci device should be ignored or not.
+ *
+ * @param pci_dev
+ *	PCI device to be validated
+ * @return
+ *	1 if device is to be ignored, 0 otherwise
+ */
+bool pci_ignore_device(const struct rte_pci_device *pci_dev);
+
 /**
  * Add a PCI device to the PCI Bus (append to PCI Device list). This function
  * also updates the bus references of the PCI Device (and the generic device
-- 
2.17.1