Re: [libvirt] [PATCH V3] nodedev: Fix failing to parse PCI address for non-PCI network devices

Commit 8708ca01c added virNetDevSwitchdevFeature() to check if a network device has Switchdev capabilities. virNetDevSwitchdevFeature() attempts to retrieve the PCI device associated with the network device, ignoring non-PCI devices. It does so via the following call chain virNetDevSwitchdevFeature()->virNetDevGetPCIDevice()-> virPCIGetDeviceAddressFromSysfsLink() For non-PCI network devices (qeth, Xen vif, etc), virPCIGetDeviceAddressFromSysfsLink() will report an error when virPCIDeviceAddressParse() fails. virPCIDeviceAddressParse() also logs an error. After commit 8708ca01c there are now two errors reported for each non-PCI network device even though the errors are harmless. To avoid the errors, introduce virNetDevIsPCIDevice() and use it in virNetDevGetPCIDevice() before attempting to retrieve the associated PCI device. virNetDevIsPCIDevice() uses the 'subsystem' property of the device to determine if it is PCI. See the sysfs rules in kernel documentation for more details https://www.kernel.org/doc/html/latest/admin-guide/sysfs-rules.html --- V2: https://www.redhat.com/archives/libvir-list/2018-January/msg00233.html Changes in V3: Implement checking if netdev is PCI in virnetdev.c instead of virpci.c Addressed other comments from eskultet src/util/virnetdev.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 46 insertions(+) diff --git a/src/util/virnetdev.c b/src/util/virnetdev.c index eb2d119bf..baf4a71fe 100644 --- a/src/util/virnetdev.c +++ b/src/util/virnetdev.c @@ -22,6 +22,7 @@ #include <config.h> +#include "dirname.h" #include "virnetdev.h" #include "virnetlink.h" #include "virmacaddr.h" @@ -1147,6 +1148,48 @@ virNetDevSysfsDeviceFile(char **pf_sysfs_device_link, const char *ifname, return 0; } +/** + * Determine if the device path specified in devpath is a PCI Device + * by resolving the 'subsystem'-link in devpath and looking for + * 'pci' in the last component. For more information see the rules + * for accessing sysfs in the kernel docs + * + * https://www.kernel.org/doc/html/latest/admin-guide/sysfs-rules.html + * + * Returns true if devpath's susbsystem is pci, false otherwise. + */ +static bool +virNetDevIsPCIDevice(const char *devpath) +{ + char *subsys_link = NULL; + char *abs_path = NULL; + char *subsys = NULL; + bool ret = false; + + if (virAsprintf(&subsys_link, "%s/subsystem", devpath) < 0) + return false; + + if (!virFileExists(subsys_link)) + goto cleanup; + + if (virFileIsLink(subsys_link) != 1) + goto cleanup; +