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Subject[RFC PATCH V2] virtio_pci: Add SR-IOV support
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Hardware-realized virtio-pci devices can implement SR-IOV, so this
patch enables its use. The device in question is an upcoming Intel
NIC that implements both a virtio-net PF and virtio-net VFs. These
are hardware realizations of what has been up to now been a software
interface.

The device in question has the following 4-part PCI IDs:

PF: device: 1af4 vendor: 1041 subvendor: 8086 subdevice: 15fe
VF: device: 1af4 vendor: 1041 subvendor: 8086 subdevice: 05fe

The patch needs no check for device ID, because the callback will
never be made for devices that do not assert the capability or
when run on a platform incapable of SR-IOV.

One reason for this patch is because the hardware requires the
vendor ID of a VF to be the same as the vendor ID of the PF that
created it. So it seemed logical to simply have a fully-functioning
virtio-net PF create the VFs. This patch makes that possible.

Signed-off-by: Mark Rustad <mark.d.rustad@intel.com>
Reviewed-by: Alexander Duyck <alexander.h.duyck@intel.com>
---
Changes in V2:
- Simplified logic from previous version, removed added driver variable
- Disable SR-IOV on driver removal excapt when VFs are assigned
- Sent as RFC to virtio-dev, linux-pci, netdev, lkml and others
---
drivers/virtio/virtio_pci_common.c | 47 ++++++++++++++++++++++++++++++++++++
1 file changed, 47 insertions(+)

diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
index 48d4d1cf1cb6..78b53ffc4cee 100644
--- a/drivers/virtio/virtio_pci_common.c
+++ b/drivers/virtio/virtio_pci_common.c
@@ -572,6 +572,47 @@ static int virtio_pci_probe(struct pci_dev *pci_dev,
return rc;
}

+#ifdef CONFIG_PCI_IOV
+static int virtio_pci_sriov_disable(struct pci_dev *pci_dev)
+{
+ /* If vfs are assigned we cannot shut down SR-IOV without causing
+ * issues, so just leave the hardware available.
+ */
+ if (pci_vfs_assigned(pci_dev)) {
+ dev_warn(&pci_dev->dev,
+ "Unloading driver while VFs are assigned - VFs will not be deallocated\n");
+ return -EPERM;
+ }
+ pci_disable_sriov(pci_dev);
+ return 0;
+}
+
+static int virtio_pci_sriov_enable(struct pci_dev *pci_dev, int num_vfs)
+{
+ int rc = 0;
+
+ if (pci_num_vf(pci_dev))
+ return -EINVAL;
+
+ rc = pci_enable_sriov(pci_dev, num_vfs);
+ if (rc) {
+ dev_warn(&pci_dev->dev, "Failed to enable PCI sriov: %d\n", rc);
+ return rc;
+ }
+ dev_info(&pci_dev->dev, "SR-IOV enabled with %d VFs\n", num_vfs);
+ return num_vfs;
+}
+
+static int virtio_pci_sriov_configure(struct pci_dev *dev, int num_vfs)
+{
+ if (num_vfs)
+ return virtio_pci_sriov_enable(dev, num_vfs);
+ if (!pci_num_vf(dev))
+ return -EINVAL;
+ return virtio_pci_sriov_disable(dev);
+}
+#endif /* CONFIG_PCI_IOV */
+
static void virtio_pci_remove(struct pci_dev *pci_dev)
{
struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev);
@@ -584,6 +625,9 @@ static void virtio_pci_remove(struct pci_dev *pci_dev)
else
virtio_pci_modern_remove(vp_dev);

+#ifdef CONFIG_PCI_IOV
+ virtio_pci_sriov_disable(pci_dev);
+#endif
pci_disable_device(pci_dev);
put_device(dev);
}
@@ -596,6 +640,9 @@ static void virtio_pci_remove(struct pci_dev *pci_dev)
#ifdef CONFIG_PM_SLEEP
.driver.pm = &virtio_pci_pm_ops,
#endif
+#ifdef CONFIG_PCI_IOV
+ .sriov_configure = virtio_pci_sriov_configure,
+#endif
};

module_pci_driver(virtio_pci_driver);
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