diff mbox series

[V4,10/13] PCI / VFIO: Add 'override_only' support for VFIO PCI sub system

Message ID 20210825135139.79034-11-yishaih@nvidia.com (mailing list archive)
State New, archived
Headers show
Series Introduce vfio_pci_core subsystem | expand

Commit Message

Yishai Hadas Aug. 25, 2021, 1:51 p.m. UTC
From: Max Gurtovoy <mgurtovoy@nvidia.com>

Expose an 'override_only' helper macro (i.e.
PCI_DRIVER_OVERRIDE_DEVICE_VFIO) for VFIO PCI sub system and add the
required code to prefix its matching entries with "vfio_" in
modules.alias file.

It allows VFIO device drivers to include match entries in the
modules.alias file produced by kbuild that are not used for normal
driver autoprobing and module autoloading. Drivers using these match
entries can be connected to the PCI device manually, by userspace, using
the existing driver_override sysfs.

For example the resulting modules.alias may have:

  alias pci:v000015B3d00001021sv*sd*bc*sc*i* mlx5_core
  alias vfio_pci:v000015B3d00001021sv*sd*bc*sc*i* mlx5_vfio_pci
  alias vfio_pci:v*d*sv*sd*bc*sc*i* vfio_pci

In this example mlx5_core and mlx5_vfio_pci match to the same PCI
device. The kernel will autoload and autobind to mlx5_core but the
kernel and udev mechanisms will ignore mlx5_vfio_pci.

When userspace wants to change a device to the VFIO subsystem it can
implement a generic algorithm:

   1) Identify the sysfs path to the device:
    /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0

   2) Get the modalias string from the kernel:
    $ cat /sys/bus/pci/devices/0000:01:00.0/modalias
    pci:v000015B3d00001021sv000015B3sd00000001bc02sc00i00

   3) Prefix it with vfio_:
    vfio_pci:v000015B3d00001021sv000015B3sd00000001bc02sc00i00

   4) Search modules.alias for the above string and select the entry that
      has the fewest *'s:
    alias vfio_pci:v000015B3d00001021sv*sd*bc*sc*i* mlx5_vfio_pci

   5) modprobe the matched module name:
    $ modprobe mlx5_vfio_pci

   6) cat the matched module name to driver_override:
    echo mlx5_vfio_pci > /sys/bus/pci/devices/0000:01:00.0/driver_override

   7) unbind device from original module
     echo 0000:01:00.0 > /sys/bus/pci/devices/0000:01:00.0/driver/unbind

   8) probe PCI drivers (or explicitly bind to mlx5_vfio_pci)
    echo 0000:01:00.0 > /sys/bus/pci/drivers_probe

The algorithm is independent of bus type. In future the other buses with
VFIO device drivers, like platform and ACPI, can use this algorithm as
well.

This patch is the infrastructure to provide the information in the
modules.alias to userspace. Convert the only VFIO pci_driver which results
in one new line in the modules.alias:

  alias vfio_pci:v*d*sv*sd*bc*sc*i* vfio_pci

Later series introduce additional HW specific VFIO PCI drivers, such as
mlx5_vfio_pci.

Signed-off-by: Max Gurtovoy <mgurtovoy@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
---
 drivers/vfio/pci/vfio_pci.c       |  9 ++++++++-
 include/linux/mod_devicetable.h   |  4 ++++
 include/linux/pci.h               | 14 ++++++++++++++
 scripts/mod/devicetable-offsets.c |  1 +
 scripts/mod/file2alias.c          |  8 ++++++--
 5 files changed, 33 insertions(+), 3 deletions(-)

Comments

Bjorn Helgaas Aug. 25, 2021, 3:55 p.m. UTC | #1
On Wed, Aug 25, 2021 at 04:51:36PM +0300, Yishai Hadas wrote:
> From: Max Gurtovoy <mgurtovoy@nvidia.com>
> 
> Expose an 'override_only' helper macro (i.e.
> PCI_DRIVER_OVERRIDE_DEVICE_VFIO) for VFIO PCI sub system and add the
> required code to prefix its matching entries with "vfio_" in
> modules.alias file.
> 
> It allows VFIO device drivers to include match entries in the
> modules.alias file produced by kbuild that are not used for normal
> driver autoprobing and module autoloading. Drivers using these match
> entries can be connected to the PCI device manually, by userspace, using
> the existing driver_override sysfs.
> 
> For example the resulting modules.alias may have:
> 
>   alias pci:v000015B3d00001021sv*sd*bc*sc*i* mlx5_core
>   alias vfio_pci:v000015B3d00001021sv*sd*bc*sc*i* mlx5_vfio_pci
>   alias vfio_pci:v*d*sv*sd*bc*sc*i* vfio_pci
> 
> In this example mlx5_core and mlx5_vfio_pci match to the same PCI
> device. The kernel will autoload and autobind to mlx5_core but the
> kernel and udev mechanisms will ignore mlx5_vfio_pci.
> 
> When userspace wants to change a device to the VFIO subsystem it can
> implement a generic algorithm:
> 
>    1) Identify the sysfs path to the device:
>     /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0
> 
>    2) Get the modalias string from the kernel:
>     $ cat /sys/bus/pci/devices/0000:01:00.0/modalias
>     pci:v000015B3d00001021sv000015B3sd00000001bc02sc00i00
> 
>    3) Prefix it with vfio_:
>     vfio_pci:v000015B3d00001021sv000015B3sd00000001bc02sc00i00
> 
>    4) Search modules.alias for the above string and select the entry that
>       has the fewest *'s:
>     alias vfio_pci:v000015B3d00001021sv*sd*bc*sc*i* mlx5_vfio_pci
> 
>    5) modprobe the matched module name:
>     $ modprobe mlx5_vfio_pci
> 
>    6) cat the matched module name to driver_override:
>     echo mlx5_vfio_pci > /sys/bus/pci/devices/0000:01:00.0/driver_override
> 
>    7) unbind device from original module
>      echo 0000:01:00.0 > /sys/bus/pci/devices/0000:01:00.0/driver/unbind
> 
>    8) probe PCI drivers (or explicitly bind to mlx5_vfio_pci)
>     echo 0000:01:00.0 > /sys/bus/pci/drivers_probe
> 
> The algorithm is independent of bus type. In future the other buses with
> VFIO device drivers, like platform and ACPI, can use this algorithm as
> well.
> 
> This patch is the infrastructure to provide the information in the
> modules.alias to userspace. Convert the only VFIO pci_driver which results
> in one new line in the modules.alias:
> 
>   alias vfio_pci:v*d*sv*sd*bc*sc*i* vfio_pci
> 
> Later series introduce additional HW specific VFIO PCI drivers, such as
> mlx5_vfio_pci.
> 
> Signed-off-by: Max Gurtovoy <mgurtovoy@nvidia.com>
> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
> Signed-off-by: Yishai Hadas <yishaih@nvidia.com>

Acked-by: Bjorn Helgaas <bhelgaas@google.com>  # for pci.h

> ---
>  drivers/vfio/pci/vfio_pci.c       |  9 ++++++++-
>  include/linux/mod_devicetable.h   |  4 ++++
>  include/linux/pci.h               | 14 ++++++++++++++
>  scripts/mod/devicetable-offsets.c |  1 +
>  scripts/mod/file2alias.c          |  8 ++++++--
>  5 files changed, 33 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> index 163e560c4495..85fd638a5955 100644
> --- a/drivers/vfio/pci/vfio_pci.c
> +++ b/drivers/vfio/pci/vfio_pci.c
> @@ -178,9 +178,16 @@ static int vfio_pci_sriov_configure(struct pci_dev *pdev, int nr_virtfn)
>  	return vfio_pci_core_sriov_configure(pdev, nr_virtfn);
>  }
>  
> +static const struct pci_device_id vfio_pci_table[] = {
> +	{ PCI_DRIVER_OVERRIDE_DEVICE_VFIO(PCI_ANY_ID, PCI_ANY_ID) }, /* match all by default */
> +	{}
> +};
> +
> +MODULE_DEVICE_TABLE(pci, vfio_pci_table);
> +
>  static struct pci_driver vfio_pci_driver = {
>  	.name			= "vfio-pci",
> -	.id_table		= NULL, /* only dynamic ids */
> +	.id_table		= vfio_pci_table,
>  	.probe			= vfio_pci_probe,
>  	.remove			= vfio_pci_remove,
>  	.sriov_configure	= vfio_pci_sriov_configure,
> diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h
> index 2e3ba6d9ece0..f0325a172f87 100644
> --- a/include/linux/mod_devicetable.h
> +++ b/include/linux/mod_devicetable.h
> @@ -16,6 +16,10 @@ typedef unsigned long kernel_ulong_t;
>  
>  #define PCI_ANY_ID (~0)
>  
> +enum {
> +	PCI_ID_F_VFIO_DRIVER_OVERRIDE	= 1 << 0,
> +};
> +
>  /**
>   * struct pci_device_id - PCI device ID structure
>   * @vendor:		Vendor ID to match (or PCI_ANY_ID)
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 0506b1a8c921..527a1dfd1d06 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -916,6 +916,20 @@ struct pci_driver {
>  	.vendor = (vend), .device = (dev), .subvendor = PCI_ANY_ID, \
>  	.subdevice = PCI_ANY_ID, .override_only = (driver_override)
>  
> +/**
> + * PCI_DRIVER_OVERRIDE_DEVICE_VFIO - macro used to describe a VFIO
> + *                                   "driver_override" PCI device.
> + * @vend: the 16 bit PCI Vendor ID
> + * @dev: the 16 bit PCI Device ID
> + *
> + * This macro is used to create a struct pci_device_id that matches a
> + * specific device. The subvendor and subdevice fields will be set to
> + * PCI_ANY_ID and the driver_override will be set to
> + * PCI_ID_F_VFIO_DRIVER_OVERRIDE.
> + */
> +#define PCI_DRIVER_OVERRIDE_DEVICE_VFIO(vend, dev) \
> +	PCI_DEVICE_DRIVER_OVERRIDE(vend, dev, PCI_ID_F_VFIO_DRIVER_OVERRIDE)
> +
>  /**
>   * PCI_DEVICE_SUB - macro used to describe a specific PCI device with subsystem
>   * @vend: the 16 bit PCI Vendor ID
> diff --git a/scripts/mod/devicetable-offsets.c b/scripts/mod/devicetable-offsets.c
> index 9bb6c7edccc4..cc3625617a0e 100644
> --- a/scripts/mod/devicetable-offsets.c
> +++ b/scripts/mod/devicetable-offsets.c
> @@ -42,6 +42,7 @@ int main(void)
>  	DEVID_FIELD(pci_device_id, subdevice);
>  	DEVID_FIELD(pci_device_id, class);
>  	DEVID_FIELD(pci_device_id, class_mask);
> +	DEVID_FIELD(pci_device_id, override_only);
>  
>  	DEVID(ccw_device_id);
>  	DEVID_FIELD(ccw_device_id, match_flags);
> diff --git a/scripts/mod/file2alias.c b/scripts/mod/file2alias.c
> index 7c97fa8e36bc..c3edbf73157e 100644
> --- a/scripts/mod/file2alias.c
> +++ b/scripts/mod/file2alias.c
> @@ -426,7 +426,7 @@ static int do_ieee1394_entry(const char *filename,
>  	return 1;
>  }
>  
> -/* Looks like: pci:vNdNsvNsdNbcNscNiN. */
> +/* Looks like: pci:vNdNsvNsdNbcNscNiN or <prefix>_pci:vNdNsvNsdNbcNscNiN. */
>  static int do_pci_entry(const char *filename,
>  			void *symval, char *alias)
>  {
> @@ -440,8 +440,12 @@ static int do_pci_entry(const char *filename,
>  	DEF_FIELD(symval, pci_device_id, subdevice);
>  	DEF_FIELD(symval, pci_device_id, class);
>  	DEF_FIELD(symval, pci_device_id, class_mask);
> +	DEF_FIELD(symval, pci_device_id, override_only);
>  
> -	strcpy(alias, "pci:");
> +	if (override_only & PCI_ID_F_VFIO_DRIVER_OVERRIDE)
> +		strcpy(alias, "vfio_pci:");
> +	else
> +		strcpy(alias, "pci:");
>  	ADD(alias, "v", vendor != PCI_ANY_ID, vendor);
>  	ADD(alias, "d", device != PCI_ANY_ID, device);
>  	ADD(alias, "sv", subvendor != PCI_ANY_ID, subvendor);
> -- 
> 2.18.1
>
Alex Williamson Aug. 25, 2021, 10:05 p.m. UTC | #2
On Wed, 25 Aug 2021 16:51:36 +0300
Yishai Hadas <yishaih@nvidia.com> wrote:
> diff --git a/scripts/mod/file2alias.c b/scripts/mod/file2alias.c
> index 7c97fa8e36bc..c3edbf73157e 100644
> --- a/scripts/mod/file2alias.c
> +++ b/scripts/mod/file2alias.c
> @@ -426,7 +426,7 @@ static int do_ieee1394_entry(const char *filename,
>  	return 1;
>  }
>  
> -/* Looks like: pci:vNdNsvNsdNbcNscNiN. */
> +/* Looks like: pci:vNdNsvNsdNbcNscNiN or <prefix>_pci:vNdNsvNsdNbcNscNiN. */
>  static int do_pci_entry(const char *filename,
>  			void *symval, char *alias)
>  {
> @@ -440,8 +440,12 @@ static int do_pci_entry(const char *filename,
>  	DEF_FIELD(symval, pci_device_id, subdevice);
>  	DEF_FIELD(symval, pci_device_id, class);
>  	DEF_FIELD(symval, pci_device_id, class_mask);
> +	DEF_FIELD(symval, pci_device_id, override_only);
>  
> -	strcpy(alias, "pci:");
> +	if (override_only & PCI_ID_F_VFIO_DRIVER_OVERRIDE)
> +		strcpy(alias, "vfio_pci:");
> +	else
> +		strcpy(alias, "pci:");

I'm a little concerned that we're allowing unknown, non-zero
override_only values to fall through to create "pci:" alias matches.
Should this be something like:

	if (override_only & PCI_ID_F_VFIO_DRIVER_OVERRIDE) {
		strcpy(alias, "vfio_pci:");
	} else if (override_only) {
		warn("Unknown PCI driver_override alias %08X\n",
			driver_override);
		return 0;
	} else {
		strcpy(alias, "pci:");
	}

And then if we can only have a single bit set in override_only (I
can't think of a use case for a single entry to have multiple
override options), should PCI_DEVICE_DRIVER_OVERRIDE() be defined to
take a "driver_override_shift" value where .driver_override is assigned
(1 << driver_override_shift)?  That would encode the semantics in the
prototypes a little better.  Thanks,

Alex

>  	ADD(alias, "v", vendor != PCI_ANY_ID, vendor);
>  	ADD(alias, "d", device != PCI_ANY_ID, device);
>  	ADD(alias, "sv", subvendor != PCI_ANY_ID, subvendor);
Jason Gunthorpe Aug. 25, 2021, 10:24 p.m. UTC | #3
On Wed, Aug 25, 2021 at 04:05:46PM -0600, Alex Williamson wrote:
> On Wed, 25 Aug 2021 16:51:36 +0300
> Yishai Hadas <yishaih@nvidia.com> wrote:
> > diff --git a/scripts/mod/file2alias.c b/scripts/mod/file2alias.c
> > index 7c97fa8e36bc..c3edbf73157e 100644
> > +++ b/scripts/mod/file2alias.c
> > @@ -426,7 +426,7 @@ static int do_ieee1394_entry(const char *filename,
> >  	return 1;
> >  }
> >  
> > -/* Looks like: pci:vNdNsvNsdNbcNscNiN. */
> > +/* Looks like: pci:vNdNsvNsdNbcNscNiN or <prefix>_pci:vNdNsvNsdNbcNscNiN. */
> >  static int do_pci_entry(const char *filename,
> >  			void *symval, char *alias)
> >  {
> > @@ -440,8 +440,12 @@ static int do_pci_entry(const char *filename,
> >  	DEF_FIELD(symval, pci_device_id, subdevice);
> >  	DEF_FIELD(symval, pci_device_id, class);
> >  	DEF_FIELD(symval, pci_device_id, class_mask);
> > +	DEF_FIELD(symval, pci_device_id, override_only);
> >  
> > -	strcpy(alias, "pci:");
> > +	if (override_only & PCI_ID_F_VFIO_DRIVER_OVERRIDE)
> > +		strcpy(alias, "vfio_pci:");
> > +	else
> > +		strcpy(alias, "pci:");
> 
> I'm a little concerned that we're allowing unknown, non-zero
> override_only values to fall through to create "pci:" alias matches.
> Should this be something like:
> 
> 	if (override_only & PCI_ID_F_VFIO_DRIVER_OVERRIDE) {

Should probably be == not &, since in this new arrangement it is
really more of an enum than a bit flags... A switch would be OK here
too

> 		strcpy(alias, "vfio_pci:");
> 	} else if (override_only) {
> 		warn("Unknown PCI driver_override alias %08X\n",
> 			driver_override);
> 		return 0;
> 	} else {
> 		strcpy(alias, "pci:");
> 	}

It seems reasonable to me to throw a warn, it signals to a future
developer that kbuild is not working right.

> And then if we can only have a single bit set in override_only (I
> can't think of a use case for a single entry to have multiple
> override options), should PCI_DEVICE_DRIVER_OVERRIDE() be defined to
> take a "driver_override_shift" value where .driver_override is assigned
> (1 << driver_override_shift)?  That would encode the semantics in the
> prototypes a little better.  

I think it is just an enum of overrides, no reason to make it one hot
encoded. Previously when it was flags the bit encode had a certain
amount of logic, but no longer.

Jason
Alex Williamson Aug. 25, 2021, 10:33 p.m. UTC | #4
On Wed, 25 Aug 2021 19:24:43 -0300
Jason Gunthorpe <jgg@nvidia.com> wrote:

> On Wed, Aug 25, 2021 at 04:05:46PM -0600, Alex Williamson wrote:
> > On Wed, 25 Aug 2021 16:51:36 +0300
> > Yishai Hadas <yishaih@nvidia.com> wrote:  
> > > diff --git a/scripts/mod/file2alias.c b/scripts/mod/file2alias.c
> > > index 7c97fa8e36bc..c3edbf73157e 100644
> > > +++ b/scripts/mod/file2alias.c
> > > @@ -426,7 +426,7 @@ static int do_ieee1394_entry(const char *filename,
> > >  	return 1;
> > >  }
> > >  
> > > -/* Looks like: pci:vNdNsvNsdNbcNscNiN. */
> > > +/* Looks like: pci:vNdNsvNsdNbcNscNiN or <prefix>_pci:vNdNsvNsdNbcNscNiN. */
> > >  static int do_pci_entry(const char *filename,
> > >  			void *symval, char *alias)
> > >  {
> > > @@ -440,8 +440,12 @@ static int do_pci_entry(const char *filename,
> > >  	DEF_FIELD(symval, pci_device_id, subdevice);
> > >  	DEF_FIELD(symval, pci_device_id, class);
> > >  	DEF_FIELD(symval, pci_device_id, class_mask);
> > > +	DEF_FIELD(symval, pci_device_id, override_only);
> > >  
> > > -	strcpy(alias, "pci:");
> > > +	if (override_only & PCI_ID_F_VFIO_DRIVER_OVERRIDE)
> > > +		strcpy(alias, "vfio_pci:");
> > > +	else
> > > +		strcpy(alias, "pci:");  
> > 
> > I'm a little concerned that we're allowing unknown, non-zero
> > override_only values to fall through to create "pci:" alias matches.
> > Should this be something like:
> > 
> > 	if (override_only & PCI_ID_F_VFIO_DRIVER_OVERRIDE) {  
> 
> Should probably be == not &, since in this new arrangement it is
> really more of an enum than a bit flags... A switch would be OK here
> too
> 
> > 		strcpy(alias, "vfio_pci:");
> > 	} else if (override_only) {
> > 		warn("Unknown PCI driver_override alias %08X\n",
> > 			driver_override);
> > 		return 0;
> > 	} else {
> > 		strcpy(alias, "pci:");
> > 	}  
> 
> It seems reasonable to me to throw a warn, it signals to a future
> developer that kbuild is not working right.
> 
> > And then if we can only have a single bit set in override_only (I
> > can't think of a use case for a single entry to have multiple
> > override options), should PCI_DEVICE_DRIVER_OVERRIDE() be defined to
> > take a "driver_override_shift" value where .driver_override is assigned
> > (1 << driver_override_shift)?  That would encode the semantics in the
> > prototypes a little better.    
> 
> I think it is just an enum of overrides, no reason to make it one hot
> encoded. Previously when it was flags the bit encode had a certain
> amount of logic, but no longer.

Yeah, a switch statement handling pci:/vfio_pci:/warn rather than
testing bits would clear things up for me.  Thanks,

Alex
diff mbox series

Patch

diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index 163e560c4495..85fd638a5955 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -178,9 +178,16 @@  static int vfio_pci_sriov_configure(struct pci_dev *pdev, int nr_virtfn)
 	return vfio_pci_core_sriov_configure(pdev, nr_virtfn);
 }
 
+static const struct pci_device_id vfio_pci_table[] = {
+	{ PCI_DRIVER_OVERRIDE_DEVICE_VFIO(PCI_ANY_ID, PCI_ANY_ID) }, /* match all by default */
+	{}
+};
+
+MODULE_DEVICE_TABLE(pci, vfio_pci_table);
+
 static struct pci_driver vfio_pci_driver = {
 	.name			= "vfio-pci",
-	.id_table		= NULL, /* only dynamic ids */
+	.id_table		= vfio_pci_table,
 	.probe			= vfio_pci_probe,
 	.remove			= vfio_pci_remove,
 	.sriov_configure	= vfio_pci_sriov_configure,
diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h
index 2e3ba6d9ece0..f0325a172f87 100644
--- a/include/linux/mod_devicetable.h
+++ b/include/linux/mod_devicetable.h
@@ -16,6 +16,10 @@  typedef unsigned long kernel_ulong_t;
 
 #define PCI_ANY_ID (~0)
 
+enum {
+	PCI_ID_F_VFIO_DRIVER_OVERRIDE	= 1 << 0,
+};
+
 /**
  * struct pci_device_id - PCI device ID structure
  * @vendor:		Vendor ID to match (or PCI_ANY_ID)
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 0506b1a8c921..527a1dfd1d06 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -916,6 +916,20 @@  struct pci_driver {
 	.vendor = (vend), .device = (dev), .subvendor = PCI_ANY_ID, \
 	.subdevice = PCI_ANY_ID, .override_only = (driver_override)
 
+/**
+ * PCI_DRIVER_OVERRIDE_DEVICE_VFIO - macro used to describe a VFIO
+ *                                   "driver_override" PCI device.
+ * @vend: the 16 bit PCI Vendor ID
+ * @dev: the 16 bit PCI Device ID
+ *
+ * This macro is used to create a struct pci_device_id that matches a
+ * specific device. The subvendor and subdevice fields will be set to
+ * PCI_ANY_ID and the driver_override will be set to
+ * PCI_ID_F_VFIO_DRIVER_OVERRIDE.
+ */
+#define PCI_DRIVER_OVERRIDE_DEVICE_VFIO(vend, dev) \
+	PCI_DEVICE_DRIVER_OVERRIDE(vend, dev, PCI_ID_F_VFIO_DRIVER_OVERRIDE)
+
 /**
  * PCI_DEVICE_SUB - macro used to describe a specific PCI device with subsystem
  * @vend: the 16 bit PCI Vendor ID
diff --git a/scripts/mod/devicetable-offsets.c b/scripts/mod/devicetable-offsets.c
index 9bb6c7edccc4..cc3625617a0e 100644
--- a/scripts/mod/devicetable-offsets.c
+++ b/scripts/mod/devicetable-offsets.c
@@ -42,6 +42,7 @@  int main(void)
 	DEVID_FIELD(pci_device_id, subdevice);
 	DEVID_FIELD(pci_device_id, class);
 	DEVID_FIELD(pci_device_id, class_mask);
+	DEVID_FIELD(pci_device_id, override_only);
 
 	DEVID(ccw_device_id);
 	DEVID_FIELD(ccw_device_id, match_flags);
diff --git a/scripts/mod/file2alias.c b/scripts/mod/file2alias.c
index 7c97fa8e36bc..c3edbf73157e 100644
--- a/scripts/mod/file2alias.c
+++ b/scripts/mod/file2alias.c
@@ -426,7 +426,7 @@  static int do_ieee1394_entry(const char *filename,
 	return 1;
 }
 
-/* Looks like: pci:vNdNsvNsdNbcNscNiN. */
+/* Looks like: pci:vNdNsvNsdNbcNscNiN or <prefix>_pci:vNdNsvNsdNbcNscNiN. */
 static int do_pci_entry(const char *filename,
 			void *symval, char *alias)
 {
@@ -440,8 +440,12 @@  static int do_pci_entry(const char *filename,
 	DEF_FIELD(symval, pci_device_id, subdevice);
 	DEF_FIELD(symval, pci_device_id, class);
 	DEF_FIELD(symval, pci_device_id, class_mask);
+	DEF_FIELD(symval, pci_device_id, override_only);
 
-	strcpy(alias, "pci:");
+	if (override_only & PCI_ID_F_VFIO_DRIVER_OVERRIDE)
+		strcpy(alias, "vfio_pci:");
+	else
+		strcpy(alias, "pci:");
 	ADD(alias, "v", vendor != PCI_ANY_ID, vendor);
 	ADD(alias, "d", device != PCI_ANY_ID, device);
 	ADD(alias, "sv", subvendor != PCI_ANY_ID, subvendor);