linux-kernel - [RFC 1/2] PCI/IOV: Introduce pci_iov_sysfs

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Message-Id: <20200506154139.90609-2-schnelle@linux.ibm.com>
Date:   Wed,  6 May 2020 17:41:38 +0200
From:   Niklas Schnelle <schnelle@...ux.ibm.com>
To:     Bjorn Helgaas <bhelgaas@...gle.com>
Cc:     linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        Pierre Morel <pmorel@...ux.ibm.com>,
        Peter Oberparleiter <oberpar@...ux.ibm.com>
Subject: [RFC 1/2] PCI/IOV: Introduce pci_iov_sysfs_link() function

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@...ux.ibm.com>
---
 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