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[PATCH] util: Add phys_port_name support on virPCIGetNetName



Current virPCIGetNetName() logic is to get net device name by checking
it's phys_port_id, if caller provide it, or by it's index (eg, by it's
position at sysfs net directory). This approach worked fine up until
linux kernel version 5.8, where NVIDIA Mellanox driver implemented
linking of VFs' representors to PCI device in switchdev mode. This mean
that device's sysfs net directory will hold multiple net devices. Ex.:

$ ls '/sys/bus/pci/devices/0000:82:00.0/net'
ens1f0  eth0  eth1

Most switch devices support phys_port_name instead of phys_port_id, so
virPCIGetNetName() will try to get PF name by it's index - 0. The
problem here is that the PF nedev entry may not be the first.

To fix that, for switch devices, we introduce a new logic to select the
PF uplink netdev according to the content of phys_port_name. Extend
virPCIGetNetName() with physPortNameRegex variable to get proper device
by it's phys_port_name scheme, for ex., "p[0-9]+$" to get PF,
"pf[0-9]+vf[0-9]+$" to get VF or "p1$" to get exact net device. So now
virPCIGetNetName() logic work in following sequence:
 - filter by phys_port_id, if it's provided,
 or
 - filter by phys_port_name, if it's regex provided,
 or
 - get net device by it's index (position) in sysfs net directory.
Also, make getting content of iface sysfs files more generic.

Signed-off-by: Dmytro Linkin <dlinkin nvidia com>
Reviewed-by: Adrian Chiris <adrianc nvidia com>
---
 src/hypervisor/virhostdev.c |  2 +-
 src/util/virnetdev.c        | 74 ++++++++++++++++++++++++++++++++++++---------
 src/util/virnetdev.h        |  4 +++
 src/util/virpci.c           | 63 ++++++++++++++++++++++++++++++++++++--
 src/util/virpci.h           |  6 ++++
 5 files changed, 130 insertions(+), 19 deletions(-)

diff --git a/src/hypervisor/virhostdev.c b/src/hypervisor/virhostdev.c
index 69102b8..1f5c347 100644
--- a/src/hypervisor/virhostdev.c
+++ b/src/hypervisor/virhostdev.c
@@ -333,7 +333,7 @@ virHostdevNetDevice(virDomainHostdevDefPtr hostdev,
          * type='hostdev'>, and it is only those devices that should
          * end up calling this function.
          */
-        if (virPCIGetNetName(sysfs_path, 0, NULL, linkdev) < 0)
+        if (virPCIGetNetName(sysfs_path, 0, NULL, NULL, linkdev) < 0)
             return -1;
 
         if (!(*linkdev)) {
diff --git a/src/util/virnetdev.c b/src/util/virnetdev.c
index b42fa86..99e3b35 100644
--- a/src/util/virnetdev.c
+++ b/src/util/virnetdev.c
@@ -1112,6 +1112,29 @@ virNetDevGetPCIDevice(const char *devName)
 }
 
 
+/* A wrapper to get content of file from ifname SYSFS_NET_DIR
+ */
+static int
+virNetDevGetSysfsFileValue(const char *ifname,
+                           const char *fileName,
+                           char **sysfsFileData)
+{
+    g_autofree char *sysfsFile = NULL;
+
+    *sysfsFileData = NULL;
+
+    if (virNetDevSysfsFile(&sysfsFile, ifname, fileName) < 0)
+        return -1;
+
+    /* a failure to read just means the driver doesn't support
+     * <fileName>, so set success now and ignore the return from
+     * virFileReadAllQuiet().
+     */
+
+    ignore_value(virFileReadAllQuiet(sysfsFile, 1024, sysfsFileData));
+    return 0;
+}
+
 /**
  * virNetDevGetPhysPortID:
  *
@@ -1130,20 +1153,29 @@ int
 virNetDevGetPhysPortID(const char *ifname,
                        char **physPortID)
 {
-    g_autofree char *physPortIDFile = NULL;
-
-    *physPortID = NULL;
-
-    if (virNetDevSysfsFile(&physPortIDFile, ifname, "phys_port_id") < 0)
-        return -1;
+    return virNetDevGetSysfsFileValue(ifname, "phys_port_id", physPortID);
+}
 
-    /* a failure to read just means the driver doesn't support
-     * phys_port_id, so set success now and ignore the return from
-     * virFileReadAllQuiet().
-     */
 
-    ignore_value(virFileReadAllQuiet(physPortIDFile, 1024, physPortID));
-    return 0;
+/**
+ * virNetDevGetPhysPortName:
+ *
+ * @ifname: name of a netdev
+ *
+ * @physPortName: pointer to char* that will receive @ifname's
+ *                phys_port_name from sysfs (null terminated
+ *                string). Could be NULL if @ifname's net driver doesn't
+ *                support phys_port_name (most netdev drivers
+ *                don't). Caller is responsible for freeing the string
+ *                when finished.
+ *
+ * Returns 0 on success or -1 on failure.
+ */
+int
+virNetDevGetPhysPortName(const char *ifname,
+                         char **physPortName)
+{
+    return virNetDevGetSysfsFileValue(ifname, "phys_port_name", physPortName);
 }
 
 
@@ -1200,7 +1232,7 @@ virNetDevGetVirtualFunctions(const char *pfname,
         }
 
         if (virPCIGetNetName(pci_sysfs_device_link, 0,
-                             pfPhysPortID, &((*vfname)[i])) < 0) {
+                             pfPhysPortID, NULL, &((*vfname)[i])) < 0) {
             goto cleanup;
         }
 
@@ -1295,7 +1327,8 @@ virNetDevGetPhysicalFunction(const char *ifname, char **pfname)
         return -1;
 
     if (virPCIGetNetName(physfn_sysfs_path, 0,
-                         vfPhysPortID, pfname) < 0) {
+                         vfPhysPortID,
+                         VIR_PF_PHYS_PORT_NAME_REGEX, pfname) < 0) {
         return -1;
     }
 
@@ -1358,7 +1391,7 @@ virNetDevPFGetVF(const char *pfname, int vf, char **vfname)
      * isn't bound to a netdev driver, it won't have a netdev name,
      * and vfname will be NULL).
      */
-    return virPCIGetNetName(virtfnSysfsPath, 0, pfPhysPortID, vfname);
+    return virPCIGetNetName(virtfnSysfsPath, 0, pfPhysPortID, NULL, vfname);
 }
 
 
@@ -1403,6 +1436,17 @@ virNetDevGetPhysPortID(const char *ifname G_GNUC_UNUSED,
 }
 
 int
+virNetDevGetPhysPortName(const char *ifname G_GNUC_UNUSED,
+                       char **physPortName)
+{
+    /* this actually should never be called, and is just here to
+     * satisfy the linker.
+     */
+    *physPortName = NULL;
+    return 0;
+}
+
+int
 virNetDevGetVirtualFunctions(const char *pfname G_GNUC_UNUSED,
                              char ***vfname G_GNUC_UNUSED,
                              virPCIDeviceAddressPtr **virt_fns G_GNUC_UNUSED,
diff --git a/src/util/virnetdev.h b/src/util/virnetdev.h
index 55e3948..712421d 100644
--- a/src/util/virnetdev.h
+++ b/src/util/virnetdev.h
@@ -229,6 +229,10 @@ int virNetDevGetPhysPortID(const char *ifname,
                            char **physPortID)
     ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2)
     G_GNUC_WARN_UNUSED_RESULT;
+int virNetDevGetPhysPortName(const char *ifname,
+                           char **physPortName)
+    ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2)
+    G_GNUC_WARN_UNUSED_RESULT;
 
 int virNetDevGetVirtualFunctions(const char *pfname,
                                  char ***vfname,
diff --git a/src/util/virpci.c b/src/util/virpci.c
index 47c671d..18b3f66 100644
--- a/src/util/virpci.c
+++ b/src/util/virpci.c
@@ -2409,8 +2409,10 @@ virPCIDeviceAddressGetSysfsFile(virPCIDeviceAddressPtr addr,
  * virPCIGetNetName:
  * @device_link_sysfs_path: sysfs path to the PCI device
  * @idx: used to choose which netdev when there are several
- *       (ignored if physPortID is set)
+ *       (ignored if physPortID or physPortNameRegex is set)
  * @physPortID: match this string in the netdev's phys_port_id
+ *       (or NULL to ignore and use phys_port_name or idx instead)
+ * @physPortNameRegex: match this regex with netdev's phys_port_name
  *       (or NULL to ignore and use idx instead)
  * @netname: used to return the name of the netdev
  *       (set to NULL (but returns success) if there is no netdev)
@@ -2421,11 +2423,13 @@ int
 virPCIGetNetName(const char *device_link_sysfs_path,
                  size_t idx,
                  char *physPortID,
+                 char *physPortNameRegex,
                  char **netname)
 {
     g_autofree char *pcidev_sysfs_net_path = NULL;
     g_autofree char *firstEntryName = NULL;
     g_autofree char *thisPhysPortID = NULL;
+    g_autofree char *thisPhysPortName = NULL;
     int ret = -1;
     DIR *dir = NULL;
     struct dirent *entry = NULL;
@@ -2466,6 +2470,41 @@ virPCIGetNetName(const char *device_link_sysfs_path,
 
                 continue;
             }
+        } else if (physPortNameRegex) {
+            /* Most switch devices use phys_port_name instead of
+             * phys_port_id.
+             * NOTE: VFs' representors net devices can be linked to PF's PCI
+             * device, which mean that there'll be multiple net devices
+             * instances and to get a proper net device need to match on
+             * specific regex.
+             * To get PF netdev, for ex., used following regex:
+             * "(p[0-9]+$)|(p[0-9]+s[0-9]+$)"
+             * or to get exact VF's netdev next regex is used:
+             * "pf0vf1$"
+             */
+            if (virNetDevGetPhysPortName(entry->d_name, &thisPhysPortName) < 0)
+                goto cleanup;
+
+            if (thisPhysPortName) {
+                /* if this one doesn't match, keep looking */
+                if (!virStringMatch(thisPhysPortName, physPortNameRegex)) {
+                    VIR_FREE(thisPhysPortName);
+                    /* Save the first entry we find to use as a failsafe
+                     * in case we fail to match on regex.
+                     */
+                    if (!firstEntryName)
+                        firstEntryName = g_strdup(entry->d_name);
+
+                    continue;
+                }
+            } else {
+                /* Save the first entry we find to use as a failsafe in case
+                 * phys_port_name is not supported.
+                 */
+                if (!firstEntryName)
+                    firstEntryName = g_strdup(entry->d_name);
+                continue;
+            }
         } else {
             if (i++ < idx)
                 continue;
@@ -2494,6 +2533,22 @@ virPCIGetNetName(const char *device_link_sysfs_path,
                                  "phys_port_id '%s' under PCI device at %s"),
                                physPortID, device_link_sysfs_path);
             }
+        } else if (physPortNameRegex) {
+            if (firstEntryName) {
+                /* We didn't match the provided phys_port_name regex, probably
+                 * because kernel or NIC driver doesn't support it, so just
+                 * return first netname we found.
+                 */
+                *netname = firstEntryName;
+                firstEntryName = NULL;
+                ret = 0;
+            } else {
+                virReportError(VIR_ERR_INTERNAL_ERROR,
+                               _("Could not find network device with "
+                                 "phys_port_name matching regex '%s' "
+                                 "under PCI device at %s"),
+                               physPortNameRegex, device_link_sysfs_path);
+            }
         } else {
             ret = 0; /* no netdev at the given index is *not* an error */
         }
@@ -2539,7 +2594,7 @@ virPCIGetVirtualFunctionInfo(const char *vf_sysfs_device_path,
      * correct.
      */
     if (pfNetDevIdx == -1) {
-        if (virPCIGetNetName(vf_sysfs_device_path, 0, NULL, &vfname) < 0)
+        if (virPCIGetNetName(vf_sysfs_device_path, 0, NULL, NULL, &vfname) < 0)
             goto cleanup;
 
         if (vfname) {
@@ -2550,7 +2605,8 @@ virPCIGetVirtualFunctionInfo(const char *vf_sysfs_device_path,
     }
 
     if (virPCIGetNetName(pf_sysfs_device_path,
-                         pfNetDevIdx, vfPhysPortID, pfname) < 0) {
+                         pfNetDevIdx, vfPhysPortID,
+                         VIR_PF_PHYS_PORT_NAME_REGEX, pfname) < 0) {
         goto cleanup;
     }
 
@@ -2688,6 +2744,7 @@ int
 virPCIGetNetName(const char *device_link_sysfs_path G_GNUC_UNUSED,
                  size_t idx G_GNUC_UNUSED,
                  char *physPortID G_GNUC_UNUSED,
+                 char *physPortNameScheme G_GNUC_UNUSED,
                  char **netname G_GNUC_UNUSED)
 {
     virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _(unsupported));
diff --git a/src/util/virpci.h b/src/util/virpci.h
index b3322ba..6ea0873 100644
--- a/src/util/virpci.h
+++ b/src/util/virpci.h
@@ -55,6 +55,11 @@ struct _virZPCIDeviceAddress {
 
 #define VIR_PCI_DEVICE_ADDRESS_FMT "%04x:%02x:%02x.%d"
 
+/* Represents format of PF's phys_port_name in switchdev mode:
+ * 'p%u' or 'p%us%u'. New line checked since value is readed from sysfs file.
+ */
+# define VIR_PF_PHYS_PORT_NAME_REGEX ((char *)"(p[0-9]+$)|(p[0-9]+s[0-9]+$)")
+
 struct _virPCIDeviceAddress {
     unsigned int domain;
     unsigned int bus;
@@ -232,6 +237,7 @@ int virPCIDeviceAddressGetSysfsFile(virPCIDeviceAddressPtr addr,
 int virPCIGetNetName(const char *device_link_sysfs_path,
                      size_t idx,
                      char *physPortID,
+                     char *physPortNameRegex,
                      char **netname);
 
 int virPCIGetSysfsFile(char *virPCIDeviceName,
-- 
1.8.3.1


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