[dpdk-dev] [PATCH v2 1/1] bus/pci: optimise scanning with whitelist/blacklist

[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>
---
v2:
 - Added function to validate ignorance of device based on PCI address.
 - Marked device validation function as experimental.

 drivers/bus/pci/bsd/pci.c               | 15 ++++++++++-
 drivers/bus/pci/linux/pci.c             |  3 +++
 drivers/bus/pci/pci_common.c            | 34 +++++++++++++++++++++++++
 drivers/bus/pci/private.h               | 12 +++++++++
 drivers/bus/pci/rte_bus_pci_version.map |  5 ++++
 5 files changed, 68 insertions(+), 1 deletion(-)

diff --git a/drivers/bus/pci/bsd/pci.c b/drivers/bus/pci/bsd/pci.c
index ebbfeb13a..074f4556e 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_addr pci_addr;
+
+	memset(&pci_addr, 0, sizeof(struct rte_pci_addr));
 
 	/* for debug purposes, PCI can be disabled */
 	if (!rte_eal_has_pci())
@@ -357,9 +360,19 @@ rte_pci_scan(void)
 			goto error;
 		}
 
-		for (i = 0; i < conf_io.num_matches; i++)
+		for (i = 0; i < conf_io.num_matches; i++) {
+			pci_addr.domain = matches[i].pc_sel.pc_domain;
+			pci_addr.bus = matches[i].pc_sel.pc_bus;
+			pci_addr.devid = matches[i].pc_sel.pc_dev;
+			pci_addr.function = matches[i].pc_sel.pc_func;
+
+			/* Check that device should be ignored or not  */
+			if (pci_addr_ignore_device(&pci_addr))
+				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 71b0a3053..92bdad826 100644
--- a/drivers/bus/pci/linux/pci.c
+++ b/drivers/bus/pci/linux/pci.c
@@ -487,6 +487,9 @@ rte_pci_scan(void)
 		if (parse_pci_addr_format(e->d_name, sizeof(e->d_name), &addr) != 0)
 			continue;
 
+		if (pci_addr_ignore_device(&addr))
+			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..a350a1993 100644
--- a/drivers/bus/pci/pci_common.c
+++ b/drivers/bus/pci/pci_common.c
@@ -589,6 +589,40 @@ pci_dma_unmap(struct rte_device *dev, void *addr, uint64_t iova, size_t len)
 	return -1;
 }
 
+static struct rte_devargs *
+pci_addr_devargs_lookup(const struct rte_pci_addr *pci_addr)
+{
+	struct rte_devargs *devargs;
+	struct rte_pci_addr addr;
+
+	RTE_EAL_DEVARGS_FOREACH("pci", devargs) {
+		devargs->bus->parse(devargs->name, &addr);
+		if (!rte_pci_addr_cmp(pci_addr, &addr))
+			return devargs;
+	}
+	return NULL;
+}
+
+bool
+pci_addr_ignore_device(const struct rte_pci_addr *pci_addr)
+{
+	struct rte_devargs *devargs = pci_addr_devargs_lookup(pci_addr);
+
+	switch (rte_pci_bus.bus.conf.scan_mode) {
+	case RTE_BUS_SCAN_WHITELIST:
+		if (devargs && devargs->policy == RTE_DEV_WHITELISTED)
+			return false;
+		break;
+	case RTE_BUS_SCAN_UNDEFINED:
+	case RTE_BUS_SCAN_BLACKLIST:
+		if (devargs == NULL ||
+		    devargs->policy != RTE_DEV_BLACKLISTED)
+			return false;
+		break;
+	}
+	return true;
+}
+
 static bool
 pci_ignore_device(const struct rte_pci_device *dev)
 {
diff --git a/drivers/bus/pci/private.h b/drivers/bus/pci/private.h
index a205d4d9f..25075b806 100644
--- a/drivers/bus/pci/private.h
+++ b/drivers/bus/pci/private.h
@@ -42,6 +42,18 @@ int rte_pci_scan(void);
 void
 pci_name_set(struct rte_pci_device *dev);
 
+/**
+ * Validate whether a device with given pci address should be ignored or not.
+ *
+ * @param pci_addr
+ *	PCI address of device to be validated
+ * @return
+ *	1: if device is to be ignored,
+ *	0: if device is to be scanned,
+ */
+__rte_experimental
+bool pci_addr_ignore_device(const struct rte_pci_addr *pci_addr);
+
 /**
  * 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
diff --git a/drivers/bus/pci/rte_bus_pci_version.map b/drivers/bus/pci/rte_bus_pci_version.map
index 012d817e1..da4ae2640 100644
--- a/drivers/bus/pci/rte_bus_pci_version.map
+++ b/drivers/bus/pci/rte_bus_pci_version.map
@@ -16,3 +16,8 @@ DPDK_20.0 {
 
 	local: *;
 };
+
+EXPERIMENTAL {
+	# added in 20.05
+	pci_addr_ignore_device;
+};
-- 
2.17.1