[pci PATCH v3 0/3] Add support for unmanaged SR-IOV

[pci PATCH v3 0/3] Add support for unmanaged SR-IOV

[Alexander Duyck]

This series is meant to add support for SR-IOV on devices when the VFs are
not managed by the kernel. Examples of recent patches attempting to do this
include:
virto - https://patchwork.kernel.org/patch/10241225/
pci-stub - https://patchwork.kernel.org/patch/10109935/
vfio - https://patchwork.kernel.org/patch/10103353/
uio - https://patchwork.kernel.org/patch/9974031/

Since this is quickly blowing up into a multi-driver problem it is probably
best to implement this solution as generically as possible.

This series is an attempt to do that. What we do with this patch set is
provide a generic framework to enable SR-IOV in the case that the PF driver
doesn't support managing the VFs itself.

I based my patch set originally on the patch by Mark Rustad but there isn't
much left after going through and cleaning out the bits that were no longer
needed, and after incorporating the feedback from David Miller. At this point
the only items to be fully reused was his patch description which is now
present in patch 3 of the set.

I have included the authors of the original 4 patches above in the Cc here.
My hope is to get feedback and/or review on if this works for their use
cases.

My hope is that for now the pci-stub and uio driver approaches can be
addressed using the current patch that enables vfio-pci support. The only
limitation is that it is also setting the taint flag until we have a better
solution.

v2: Reduced scope back to just virtio_pci and vfio-pci
    Broke into 3 patch set from single patch
    Changed autoprobe behavior to always set when num_vfs is set non-zero
v3: Updated Documentation to clarify when sriov_unmanaged_autoprobe is used
    Wrapped vfio_pci_sriov_configure to fix build errors w/o SR-IOV in kernel

Cc: Mark Rustad <mark.d.rustad@intel.com>
Cc: Maximilian Heyne <mheyne@amazon.de>
Cc: Liang-Min Wang <liang-min.wang@intel.com>
Cc: David Woodhouse <dwmw@amazon.co.uk>

---

Alexander Duyck (3):
      pci-iov: Add support for unmanaged SR-IOV
      vfio: Add support for unmanaged or userspace managed SR-IOV
      virtio_pci: Add support for unmanaged SR-IOV on virtio_pci devices


 Documentation/ABI/testing/sysfs-bus-pci |   24 +++++++++++++
 drivers/pci/iov.c                       |   37 +++++++++++++++++++
 drivers/pci/pci-driver.c                |    2 +
 drivers/pci/pci-sysfs.c                 |   29 +++++++++++++++
 drivers/pci/pci.h                       |    4 ++
 drivers/vfio/pci/vfio_pci.c             |   59 +++++++++++++++++++++++++++++++
 drivers/virtio/virtio_pci_common.c      |    4 ++
 include/linux/pci.h                     |    1 +
 8 files changed, 158 insertions(+), 2 deletions(-)

--

[pci PATCH v3 1/3] pci-iov: Add support for unmanaged SR-IOV

[Alexander Duyck]

From: Alexander Duyck <alexander.h.duyck@intel.com>

This patch is meant to add some basic functionality to support for SR-IOV
on devices when the VFs are not managed by the kernel. The functions
provided here can be used by drivers such as vfio-pci and virtio to enable
SR-IOV on devices that are either managed by userspace, or by some sort of
firmware entity respectively.

A new sysfs value called sriov_unmanaged_autoprobe has been added. This
value is used as the drivers_autoprobe setting of the VFs when they are
being managed by an external entity such as userspace or device firmware
instead of being managed by the kernel.

One side effect of this change is that the sriov_drivers_autoprobe and
sriov_unmanaged_autoprobe will only apply their updates when SR-IOV is
disabled. Attempts to update them when SR-IOV is in use will only update
the local value and will not update sriov->autoprobe.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
---

v3: Updated documentation to better explain sriov_unmanaged_autoprobe use

 Documentation/ABI/testing/sysfs-bus-pci |   24 ++++++++++++++++++++
 drivers/pci/iov.c                       |   37 +++++++++++++++++++++++++++++++
 drivers/pci/pci-driver.c                |    2 +-
 drivers/pci/pci-sysfs.c                 |   29 ++++++++++++++++++++++++
 drivers/pci/pci.h                       |    4 +++
 include/linux/pci.h                     |    1 +
 6 files changed, 95 insertions(+), 2 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci
index 44d4b2be92fd..d9d20611fc91 100644
--- a/Documentation/ABI/testing/sysfs-bus-pci
+++ b/Documentation/ABI/testing/sysfs-bus-pci
@@ -323,3 +323,27 @@ Description:
 
 		This is similar to /sys/bus/pci/drivers_autoprobe, but
 		affects only the VFs associated with a specific PF.
+
+What:		/sys/bus/pci/devices/.../sriov_unmanaged_autoprobe
+Date:		March 2018
+Contact:	Alexander Duyck <alexander.h.duyck@intel.com>
+Description:
+		This file is associated with the PF of a device that
+		supports SR-IOV.  It determines whether newly-enabled VFs
+		are immediately bound to a driver when the PF driver does
+		not manage the VFs itself.  It initially contains 0, which
+		means the kernel will not automatically bind VFs to a driver.
+		If an application writes 1 to the file before enabling VFs,
+		the kernel will bind VFs to a compatible driver immediately
+		after they are enabled.
+
+		Currently the use of this setting is limited to drivers that
+		make use of pci_sriov_configure_unmanaged. Examples might
+		include drivers such as virtio_net which could expose a PCI
+		function that resembles a VF with the extra SR-IOV related
+		bits, or a PF attached to a vfio interface which is being
+		managed by userspace instead of the kernel directly.
+
+		This overrides /sys/bus/pci/devices/.../sriov_drivers_autoprobe
+		when a PF driver does not provide functionality to manage the
+		VFs when SR-IOV is enabled.
diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
index 677924ae0350..3dcec1fa86bd 100644
--- a/drivers/pci/iov.c
+++ b/drivers/pci/iov.c
@@ -446,6 +446,7 @@ static int sriov_init(struct pci_dev *dev, int pos)
 	pci_read_config_word(dev, pos + PCI_SRIOV_VF_DID, &iov->vf_device);
 	iov->pgsz = pgsz;
 	iov->self = dev;
+	iov->autoprobe = true;
 	iov->drivers_autoprobe = true;
 	pci_read_config_dword(dev, pos + PCI_SRIOV_CAP, &iov->cap);
 	pci_read_config_byte(dev, pos + PCI_SRIOV_FUNC_LINK, &iov->link);
@@ -683,6 +684,9 @@ int pci_enable_sriov(struct pci_dev *dev, int nr_virtfn)
 	if (!dev->is_physfn)
 		return -ENOSYS;
 
+	/* Update autoprobe setting to reflect managed device */
+	dev->sriov->autoprobe = dev->sriov->drivers_autoprobe;
+
 	return sriov_enable(dev, nr_virtfn);
 }
 EXPORT_SYMBOL_GPL(pci_enable_sriov);
@@ -807,3 +811,36 @@ int pci_sriov_get_totalvfs(struct pci_dev *dev)
 	return dev->sriov->total_VFs;
 }
 EXPORT_SYMBOL_GPL(pci_sriov_get_totalvfs);
+
+/**
+ * pci_sriov_configure_unmanaged - helper to configure unmanaged SR-IOV
+ * @dev: the PCI device
+ * @nr_virtfn: number of virtual functions to enable, 0 to disable
+ *
+ * Used to provide generic enable/disable SR-IOV option for devices
+ * that do not manage the VFs generated by their driver, or have no
+ * driver present.
+ */
+int pci_sriov_configure_unmanaged(struct pci_dev *dev, int nr_virtfn)
+{
+	int err;
+
+	might_sleep();
+
+	if (!dev->is_physfn)
+		return -ENODEV;
+
+	if (!nr_virtfn) {
+		sriov_disable(dev);
+
+		return 0;
+	}
+
+	/* Update autoprobe setting to reflect unmanaged device */
+	dev->sriov->autoprobe = dev->sriov->unmanaged_autoprobe;
+
+	err = sriov_enable(dev, nr_virtfn);
+
+	return err ? err : nr_virtfn;
+}
+EXPORT_SYMBOL_GPL(pci_sriov_configure_unmanaged);
diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index 3bed6beda051..2cc68dff6130 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -398,7 +398,7 @@ void __weak pcibios_free_irq(struct pci_dev *dev)
 #ifdef CONFIG_PCI_IOV
 static inline bool pci_device_can_probe(struct pci_dev *pdev)
 {
-	return (!pdev->is_virtfn || pdev->physfn->sriov->drivers_autoprobe);
+	return (!pdev->is_virtfn || pdev->physfn->sriov->autoprobe);
 }
 #else
 static inline bool pci_device_can_probe(struct pci_dev *pdev)
diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index eb6bee8724cc..6f78fa73e317 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -710,6 +710,30 @@ static ssize_t sriov_drivers_autoprobe_store(struct device *dev,
 	return count;
 }
 
+static ssize_t sriov_unmanaged_autoprobe_show(struct device *dev,
+					      struct device_attribute *attr,
+					      char *buf)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+
+	return sprintf(buf, "%u\n", pdev->sriov->unmanaged_autoprobe);
+}
+
+static ssize_t sriov_unmanaged_autoprobe_store(struct device *dev,
+					       struct device_attribute *attr,
+					       const char *buf, size_t count)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+	bool unmanaged_autoprobe;
+
+	if (kstrtobool(buf, &unmanaged_autoprobe) < 0)
+		return -EINVAL;
+
+	pdev->sriov->unmanaged_autoprobe = unmanaged_autoprobe;
+
+	return count;
+}
+
 static struct device_attribute sriov_totalvfs_attr = __ATTR_RO(sriov_totalvfs);
 static struct device_attribute sriov_numvfs_attr =
 		__ATTR(sriov_numvfs, (S_IRUGO|S_IWUSR|S_IWGRP),
@@ -720,6 +744,10 @@ static ssize_t sriov_drivers_autoprobe_store(struct device *dev,
 static struct device_attribute sriov_drivers_autoprobe_attr =
 		__ATTR(sriov_drivers_autoprobe, (S_IRUGO|S_IWUSR|S_IWGRP),
 		       sriov_drivers_autoprobe_show, sriov_drivers_autoprobe_store);
+static struct device_attribute sriov_unmanaged_autoprobe_attr =
+		__ATTR(sriov_unmanaged_autoprobe, (S_IRUGO|S_IWUSR|S_IWGRP),
+		       sriov_unmanaged_autoprobe_show,
+		       sriov_unmanaged_autoprobe_store);
 #endif /* CONFIG_PCI_IOV */
 
 static ssize_t driver_override_store(struct device *dev,
@@ -1789,6 +1817,7 @@ static umode_t pcie_dev_attrs_are_visible(struct kobject *kobj,
 	&sriov_stride_attr.attr,
 	&sriov_vf_device_attr.attr,
 	&sriov_drivers_autoprobe_attr.attr,
+	&sriov_unmanaged_autoprobe_attr.attr,
 	NULL,
 };
 
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index fcd81911b127..b5f8b034f02d 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -272,7 +272,9 @@ struct pci_sriov {
 	struct pci_dev	*dev;		/* Lowest numbered PF */
 	struct pci_dev	*self;		/* This PF */
 	resource_size_t	barsz[PCI_SRIOV_NUM_BARS];	/* VF BAR size */
-	bool		drivers_autoprobe; /* Auto probing of VFs by driver */
+	bool		autoprobe;	/* Auto probing of VFs by VF driver */
+	bool		drivers_autoprobe;	/* "" managed by PF driver */
+	bool		unmanaged_autoprobe;	/* "" unmanaged by kernel */
 };
 
 /* pci_dev priv_flags */
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 024a1beda008..553860a08131 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1953,6 +1953,7 @@ static inline void pci_mmcfg_late_init(void) { }
 int pci_vfs_assigned(struct pci_dev *dev);
 int pci_sriov_set_totalvfs(struct pci_dev *dev, u16 numvfs);
 int pci_sriov_get_totalvfs(struct pci_dev *dev);
+int pci_sriov_configure_unmanaged(struct pci_dev *dev, int nr_virtfn);
 resource_size_t pci_iov_resource_size(struct pci_dev *dev, int resno);
 void pci_vf_drivers_autoprobe(struct pci_dev *dev, bool probe);
 #else

[pci PATCH v3 2/3] vfio: Add support for unmanaged or userspace managed SR-IOV

[Alexander Duyck]

From: Alexander Duyck <alexander.h.duyck@intel.com>

This patch is meant to allow assignment of an SR-IOV enabled PF, as in VFs
have been generated, with vfio-pci. My understanding is the primary use
case for this is something like DPDK running the PF while the VFs are all
assigned to guests.

A secondary effect of this is that it provides an interface through which
it would be possible to enable SR-IOV on drivers that may not have a
physical function that actually manages the device.

Enabling SR-IOV should be pretty straight forward. As long as there are no
userspace processes currently controlling the interface the number of VFs
can be changed, and VFs will be generated without drivers being loaded on
the host. Once the userspace process begins controlling the interface the
number of VFs cannot be updated via the sysfs until the control is
released.

Note the VFs will have drivers load on them in the host if the
sriov_unmanaged_autoprobe is updated to a value of 1. However the behavior
of the VFs in such a setup cannot be guaranteed as the PF will not be
available until the userspace process starts and begins to manage the
device.

For now I am leaving the value as locked when the PF is being controlled
from userspace as a form of synchronization. Basically this way we cannot
have the number of VFs change out from under the process so it should not
require any notification framework, and the configuration can just be read
out via configuration space accesses.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
---
 drivers/vfio/pci/vfio_pci.c |   59 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 59 insertions(+)

diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index b0f759476900..8025d7336071 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -1224,6 +1224,8 @@ static void vfio_pci_remove(struct pci_dev *pdev)
 				VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM);
 	}
 
+	pci_disable_sriov(pdev);
+
 	if (!disable_idle_d3)
 		pci_set_power_state(pdev, PCI_D0);
 }
@@ -1260,12 +1262,69 @@ static pci_ers_result_t vfio_pci_aer_err_detected(struct pci_dev *pdev,
 	.error_detected = vfio_pci_aer_err_detected,
 };
 
+#ifdef CONFIG_PCI_IOV
+static int vfio_pci_sriov_configure(struct pci_dev *pdev, int nr_virtfn)
+{
+	struct vfio_pci_device *vdev;
+	struct vfio_device *device;
+	int err;
+
+	device = vfio_device_get_from_dev(&pdev->dev);
+	if (device == NULL)
+		return -ENODEV;
+
+	vdev = vfio_device_data(device);
+	if (vdev == NULL) {
+		vfio_device_put(device);
+		return -ENODEV;
+	}
+
+	/*
+	 * If a userspace process is already using this device just return
+	 * busy and don't allow for any changes.
+	 */
+	if (vdev->refcnt) {
+		pci_warn(pdev,
+			 "PF is currently in use, blocked until released by user\n");
+		return -EBUSY;
+	}
+
+	err = pci_sriov_configure_unmanaged(pdev, nr_virtfn);
+	if (err <= 0)
+		return err;
+
+	/*
+	 * We are now leaving VFs in the control of some unknown PF entity.
+	 *
+	 * Best case is a well behaved userspace PF is expected and any VMs
+	 * that the VFs will be assigned to are dependent on the userspace
+	 * entity anyway. An example being NFV where maybe the PF is acting
+	 * as an accelerated interface for a firewall or switch.
+	 *
+	 * Worst case is somebody really messed up and just enabled SR-IOV
+	 * on a device they were planning to assign to a VM somwhere.
+	 *
+	 * In either case it is probably best for us to set the taint flag
+	 * and warn the user since this could get really ugly really quick
+	 * if this wasn't what they were planning to do.
+	 */
+	add_taint(TAINT_USER, LOCKDEP_STILL_OK);
+	pci_warn(pdev,
+		 "Adding kernel taint for vfio-pci now managing SR-IOV PF device\n");
+
+	return nr_virtfn;
+}
+#endif /* CONFIG_PCI_IOV */
+
 static struct pci_driver vfio_pci_driver = {
 	.name		= "vfio-pci",
 	.id_table	= NULL, /* only dynamic ids */
 	.probe		= vfio_pci_probe,
 	.remove		= vfio_pci_remove,
 	.err_handler	= &vfio_err_handlers,
+#ifdef CONFIG_PCI_IOV
+	.sriov_configure = vfio_pci_sriov_configure,
+#endif
 };
 
 struct vfio_devices {

[pci PATCH v3 3/3] virtio_pci: Add support for unmanaged SR-IOV on virtio_pci devices

[Alexander Duyck]

From: Alexander Duyck <alexander.h.duyck@intel.com>

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

The patch currently 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>
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
---
 drivers/virtio/virtio_pci_common.c |    4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
index 48d4d1cf1cb6..ca1549393255 100644
--- a/drivers/virtio/virtio_pci_common.c
+++ b/drivers/virtio/virtio_pci_common.c
@@ -584,6 +584,7 @@ static void virtio_pci_remove(struct pci_dev *pci_dev)
 	else
 		virtio_pci_modern_remove(vp_dev);
 
+	pci_disable_sriov(pci_dev);
 	pci_disable_device(pci_dev);
 	put_device(dev);
 }
@@ -596,6 +597,9 @@ 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 = pci_sriov_configure_unmanaged,
+#endif
 };
 
 module_pci_driver(virtio_pci_driver);

Re: [pci PATCH v3 0/3] Add support for unmanaged SR-IOV

[Christoph Hellwig]

On Tue, Mar 06, 2018 at 11:29:08AM -0800, Alexander Duyck wrote:
> This series is meant to add support for SR-IOV on devices when the VFs are
> not managed by the kernel. Examples of recent patches attempting to do this
> include:
> virto - https://patchwork.kernel.org/patch/10241225/
> pci-stub - https://patchwork.kernel.org/patch/10109935/
> vfio - https://patchwork.kernel.org/patch/10103353/
> uio - https://patchwork.kernel.org/patch/9974031/

nvme and ema seems to be existing examples.  Care to throw in
conversions while you're at it?

Re: [pci PATCH v3 0/3] Add support for unmanaged SR-IOV

[Alexander Duyck]

On Tue, Mar 6, 2018 at 10:46 PM, Christoph Hellwig <hch@infradead.org> wrote:
> On Tue, Mar 06, 2018 at 11:29:08AM -0800, Alexander Duyck wrote:
>> This series is meant to add support for SR-IOV on devices when the VFs are
>> not managed by the kernel. Examples of recent patches attempting to do this
>> include:
>> virto - https://patchwork.kernel.org/patch/10241225/
>> pci-stub - https://patchwork.kernel.org/patch/10109935/
>> vfio - https://patchwork.kernel.org/patch/10103353/
>> uio - https://patchwork.kernel.org/patch/9974031/
>
> nvme and ema seems to be existing examples.  Care to throw in
> conversions while you're at it?

Yeah, I can do that. I assume you meant "ena" not "ema".

I'm probably looking at doing a v4 that will drop the vfio userspace
driver bits for now as it sounds like there are additional issues that
still need to be addressed.

Thanks.

- Alex