[PATCH] uio/uio_pci_generic: Add SR-IOV support

[David Woodhouse <dwmw2@infradead.org>]

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From: David Woodhouse <dwmw@amazon.co.uk>

Allow userspace to configure SR-IOV VFs through sysfs.

Currently, we need an in-kernel driver to permit this. But sometimes
*all* we want to do is enable the VFs so that we can assign them to
guests; we don't actually need to deal with the PF in any other way
from the host kernel. So let's make it possible to use UIO for that.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
---
It's not entirely clear to me why we require the driver to "enable"
SR-IOV like this anyway — were there some which needed to do something
special and device-specific instead of just falling through to
pci_{en,dis}able_sriov(), such that we need to effectively whitelist
this in the driver rather than blacklisting the "problematic" ones via
PCI quirks?

 drivers/uio/uio_pci_generic.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/uio/uio_pci_generic.c b/drivers/uio/uio_pci_generic.c
index a56fdf9..bd196f0 100644
--- a/drivers/uio/uio_pci_generic.c
+++ b/drivers/uio/uio_pci_generic.c
@@ -108,15 +108,27 @@ static void remove(struct pci_dev *pdev)
 	struct uio_pci_generic_dev *gdev = pci_get_drvdata(pdev);
 
 	uio_unregister_device(&gdev->info);
+	pci_disable_sriov(pdev);
 	pci_disable_device(pdev);
 	kfree(gdev);
 }
 
+static int sriov_configure(struct pci_dev *pdev, int num_vfs)
+{
+	if (!num_vfs) {
+		pci_disable_sriov(pdev);
+		return 0;
+	}
+
+	return pci_enable_sriov(pdev, num_vfs);
+}
+
 static struct pci_driver uio_pci_driver = {
 	.name = "uio_pci_generic",
 	.id_table = NULL, /* only dynamic id's */
 	.probe = probe,
 	.remove = remove,
+	.sriov_configure = sriov_configure,
 };
 
 module_pci_driver(uio_pci_driver);
-- 
2.7.4

-- 
dwmw2

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