[RFC 1/2] PCI/IOV: Introduce pci_iov_sysfs_link() function

From: Niklas Schnelle
Date: Wed May 06 2020 - 11:41:48 EST


currently pci_iov_add_virtfn() scans the SR-IOV bars, adds the VF to the
bus and also creates the sysfs links between the newly added VF and its
parent PF.

With pdev->no_vf_scan fencing off the entire pci_iov_add_virtfn() call
s390 as the sole pdev->no_vf_scan user thus ends up missing these sysfs
links which are required for example by QEMU/libvirt.
Instead of duplicating the code introduce a new pci_iov_sysfs_link()
function for establishing sysfs links.

Signed-off-by: Niklas Schnelle <schnelle@xxxxxxxxxxxxx>
---
drivers/pci/iov.c | 36 ++++++++++++++++++++++++------------
include/linux/pci.h | 8 ++++++++
2 files changed, 32 insertions(+), 12 deletions(-)

diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
index 4d1f392b05f9..d0ddf5f5484c 100644
--- a/drivers/pci/iov.c
+++ b/drivers/pci/iov.c
@@ -113,7 +113,6 @@ resource_size_t pci_iov_resource_size(struct pci_dev *dev, int resno)
static void pci_read_vf_config_common(struct pci_dev *virtfn)
{
struct pci_dev *physfn = virtfn->physfn;
-
/*
* Some config registers are the same across all associated VFs.
* Read them once from VF0 so we can skip reading them from the
@@ -133,12 +132,34 @@ static void pci_read_vf_config_common(struct pci_dev *virtfn)
&physfn->sriov->subsystem_device);
}

+int pci_iov_sysfs_link(struct pci_dev *dev,
+ struct pci_dev *virtfn, int id)
+{
+ int rc;
+ char buf[VIRTFN_ID_LEN];
+
+ sprintf(buf, "virtfn%u", id);
+ rc = sysfs_create_link(&dev->dev.kobj, &virtfn->dev.kobj, buf);
+ if (rc)
+ goto failed;
+ rc = sysfs_create_link(&virtfn->dev.kobj, &dev->dev.kobj, "physfn");
+ if (rc)
+ goto failed1;
+
+ kobject_uevent(&virtfn->dev.kobj, KOBJ_CHANGE);
+
+ return 0;
+failed1:
+ sysfs_remove_link(&dev->dev.kobj, buf);
+failed:
+ return rc;
+}
+
int pci_iov_add_virtfn(struct pci_dev *dev, int id)
{
int i;
int rc = -ENOMEM;
u64 size;
- char buf[VIRTFN_ID_LEN];
struct pci_dev *virtfn;
struct resource *res;
struct pci_sriov *iov = dev->sriov;
@@ -182,23 +203,14 @@ int pci_iov_add_virtfn(struct pci_dev *dev, int id)
}

pci_device_add(virtfn, virtfn->bus);
-
- sprintf(buf, "virtfn%u", id);
- rc = sysfs_create_link(&dev->dev.kobj, &virtfn->dev.kobj, buf);
+ rc = pci_iov_sysfs_link(dev, virtfn, id);
if (rc)
goto failed1;
- rc = sysfs_create_link(&virtfn->dev.kobj, &dev->dev.kobj, "physfn");
- if (rc)
- goto failed2;
-
- kobject_uevent(&virtfn->dev.kobj, KOBJ_CHANGE);

pci_bus_add_device(virtfn);

return 0;

-failed2:
- sysfs_remove_link(&dev->dev.kobj, buf);
failed1:
pci_stop_and_remove_bus_device(virtfn);
pci_dev_put(dev);
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 83ce1cdf5676..e97d27ac350a 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -2048,6 +2048,8 @@ int pci_iov_virtfn_devfn(struct pci_dev *dev, int id);

int pci_enable_sriov(struct pci_dev *dev, int nr_virtfn);
void pci_disable_sriov(struct pci_dev *dev);
+
+int pci_iov_sysfs_link(struct pci_dev *dev, struct pci_dev *virtfn, int id);
int pci_iov_add_virtfn(struct pci_dev *dev, int id);
void pci_iov_remove_virtfn(struct pci_dev *dev, int id);
int pci_num_vf(struct pci_dev *dev);
@@ -2073,6 +2075,12 @@ static inline int pci_iov_virtfn_devfn(struct pci_dev *dev, int id)
}
static inline int pci_enable_sriov(struct pci_dev *dev, int nr_virtfn)
{ return -ENODEV; }
+
+static inline int pci_iov_sysfs_link(struct pci_dev *dev,
+ struct pci_dev *virtfn, int id)
+{
+ return -ENODEV;
+}
static inline int pci_iov_add_virtfn(struct pci_dev *dev, int id)
{
return -ENOSYS;
--
2.17.1