[v2,2/2] vfio: add virtio pci quirk
diff mbox

Message ID 1472523968-9540-3-git-send-email-mst@redhat.com
State New
Headers show

Commit Message

Michael S. Tsirkin Aug. 30, 2016, 2:27 a.m. UTC
Modern virtio pci devices can set VIRTIO_F_IOMMU_PLATFORM
to signal they are safe to use with an IOMMU.

Without this bit, exposing the device to userspace is unsafe, so probe
and fail VFIO initialization unless noiommu is enabled.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 drivers/vfio/pci/vfio_pci_private.h |   1 +
 drivers/vfio/pci/vfio_pci.c         |  14 ++++
 drivers/vfio/pci/vfio_pci_virtio.c  | 140 ++++++++++++++++++++++++++++++++++++
 drivers/vfio/pci/Makefile           |   1 +
 4 files changed, 156 insertions(+)
 create mode 100644 drivers/vfio/pci/vfio_pci_virtio.c

Comments

Alex Williamson Aug. 30, 2016, 3:23 a.m. UTC | #1
On Tue, 30 Aug 2016 05:27:17 +0300
"Michael S. Tsirkin" <mst@redhat.com> wrote:

> Modern virtio pci devices can set VIRTIO_F_IOMMU_PLATFORM
> to signal they are safe to use with an IOMMU.
> 
> Without this bit, exposing the device to userspace is unsafe, so probe
> and fail VFIO initialization unless noiommu is enabled.
> 
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> ---
>  drivers/vfio/pci/vfio_pci_private.h |   1 +
>  drivers/vfio/pci/vfio_pci.c         |  14 ++++
>  drivers/vfio/pci/vfio_pci_virtio.c  | 140 ++++++++++++++++++++++++++++++++++++
>  drivers/vfio/pci/Makefile           |   1 +
>  4 files changed, 156 insertions(+)
>  create mode 100644 drivers/vfio/pci/vfio_pci_virtio.c
> 
> diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h
> index 2128de8..2bd5616 100644
> --- a/drivers/vfio/pci/vfio_pci_private.h
> +++ b/drivers/vfio/pci/vfio_pci_private.h
> @@ -139,4 +139,5 @@ static inline int vfio_pci_igd_init(struct vfio_pci_device *vdev)
>  	return -ENODEV;
>  }
>  #endif
> +extern int vfio_pci_virtio_quirk(struct vfio_pci_device *vdev, bool noiommu);
>  #endif /* VFIO_PCI_PRIVATE_H */
> diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> index d624a52..e93bf0c 100644
> --- a/drivers/vfio/pci/vfio_pci.c
> +++ b/drivers/vfio/pci/vfio_pci.c
> @@ -1236,6 +1236,20 @@ static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>  		return ret;
>  	}
>  
> +	if (pdev->vendor == PCI_VENDOR_ID_REDHAT_QUMRANET) {

Perhaps a vfio_pci_is_virtio() like vga below?  Let's test the device
ID range initially as well, this test raised a big red flag for me
whether all devices within this vendor ID were virtio.

> +		bool noiommu = vfio_is_noiommu_group_dev(&pdev->dev);

I think you can use iommu_present() for this and avoid patch 1of2.
noiommu is mutually exclusive to an iommu being present.  Seems like
all of this logic should be in the quirk itself, I'm not sure what it
buys to get the value here but wait until later to use it.  Using
iommu_present() could also move this test much earlier in
vfio_pci_probe() making the exit path easier.

> +
> +		ret = vfio_pci_virtio_quirk(vdev, noiommu);
> +		if (ret) {
> +			dev_warn(&vdev->pdev->dev,
> +				 "Failed to setup Virtio for VFIO\n");
> +			vfio_del_group_dev(&pdev->dev);
> +			vfio_iommu_group_put(group, &pdev->dev);
> +			kfree(vdev);
> +			return ret;
> +		}
> +	}
> +
>  	if (vfio_pci_is_vga(pdev)) {
>  		vga_client_register(pdev, vdev, NULL, vfio_pci_set_vga_decode);
>  		vga_set_legacy_decoding(pdev,
> diff --git a/drivers/vfio/pci/vfio_pci_virtio.c b/drivers/vfio/pci/vfio_pci_virtio.c
> new file mode 100644
> index 0000000..e1ecffd
> --- /dev/null
> +++ b/drivers/vfio/pci/vfio_pci_virtio.c
> @@ -0,0 +1,140 @@
> +/*
> + * VFIO PCI Intel Graphics support
      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> + *
> + * Copyright (C) 2016 Red Hat, Inc.  All rights reserved.
> + *	Author: Alex Williamson <alex.williamson@redhat.com>

Update.

> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * Register a device specific region through which to provide read-only
> + * access to the Intel IGD opregion.  The register defining the opregion
> + * address is also virtualized to prevent user modification.
> + */
> +
> +#include <linux/io.h>
> +#include <linux/pci.h>
> +#include <linux/uaccess.h>

Are io.h and uaccess.h needed?

> +#include <linux/vfio.h>
> +#include <linux/virtio_pci.h>
> +#include <linux/virtio_config.h>
> +
> +#include "vfio_pci_private.h"
> +
> +/**
> + * virtio_pci_find_capability - walk capabilities to find device info.
> + * @dev: the pci device
> + * @cfg_type: the VIRTIO_PCI_CAP_* value we seek
> + *
> + * Returns offset of the capability, or 0.
> + */
> +static inline int virtio_pci_find_capability(struct pci_dev *dev, u8 cfg_type)

Does inlining this really make sense?

> +{
> +	int pos;
> +
> +	for (pos = pci_find_capability(dev, PCI_CAP_ID_VNDR);
> +	     pos > 0;
> +	     pos = pci_find_next_capability(dev, pos, PCI_CAP_ID_VNDR)) {
> +		u8 type;
> +		pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
> +							 cfg_type),
> +				     &type);
> +
> +		if (type != cfg_type)
> +			continue;
> +
> +		/* Ignore structures with reserved BAR values */
> +		if (type != VIRTIO_PCI_CAP_PCI_CFG) {
> +			u8 bar;
> +
> +			pci_read_config_byte(dev, pos +
> +					     offsetof(struct virtio_pci_cap,
> +						      bar),
> +					     &bar);
> +			if (bar > 0x5)

s/0x5/PCI_STD_RESOURCE_END/

> +				continue;
> +		}
> +
> +		return pos;
> +	}
> +	return 0;
> +}
> +
> +
> +int vfio_pci_virtio_quirk(struct vfio_pci_device *vdev, bool noiommu)
> +{
> +	struct pci_dev *dev = vdev->pdev;

Please use *pdev for consistency with the rest of drivers/vfio/pci/*

Also, is there any reason to pass the vfio_pci_device?  There's nothing
vfio here otherwise and we could remove more #includes.

> +	int common, cfg;
> +	u32 features;
> +	u32 offset;
> +	u8 bar;
> +
> +	/* Without an IOMMU, we don't care */
> +	if (noiommu)
> +		return 0;
> +
> +        /* Virtio only owns devices >= 0x1000 and <= 0x107f: leave the rest. */
> +        if (dev->device < 0x1000 || dev->device > 0x107f)
> +                return 0;

Whitespace

> +
> +	/* Check whether device enforces the IOMMU correctly */
> +
> +	/*
> +	 * All modern devices must have common and cfg capabilities. We use cfg
> +	 * capability for access so that we don't need to worry about resource
> +	 * availability. Slow but sure.
> +	 * Note that all vendor-specific fields we access are little-endian
> +	 * which matches what pci config accessors expect, so they do byteswap
> +	 * for us if appropriate.
> +	 */
> +	common = virtio_pci_find_capability(dev, VIRTIO_PCI_CAP_COMMON_CFG);
> +	cfg = virtio_pci_find_capability(dev, VIRTIO_PCI_CAP_PCI_CFG);
> +	if (!cfg || !common) {
> +                dev_warn(&dev->dev,
> +                         "Virtio device lacks common or pci cfg.\n");

Whitespace

> +		return -ENODEV;
> +	}
> +
> +	pci_read_config_byte(dev, common + offsetof(struct virtio_pci_cap,
> +						    bar),
> +			     &bar);
> +	pci_read_config_dword(dev, common + offsetof(struct virtio_pci_cap,
> +						    offset),
> +			     &offset);
> +
> +	/* Program cfg capability for dword access into common cfg. */
> +	pci_write_config_byte(dev, cfg + offsetof(struct virtio_pci_cfg_cap,
> +						  cap.bar),
> +			      bar);
> +	pci_write_config_dword(dev, cfg + offsetof(struct virtio_pci_cfg_cap,
> +						   cap.length),
> +			       0x4);
> +
> +	/* Select features dword that has VIRTIO_F_IOMMU_PLATFORM. */
> +	pci_write_config_dword(dev, cfg + offsetof(struct virtio_pci_cfg_cap,
> +						  cap.offset),
> +			       offset + offsetof(struct virtio_pci_common_cfg,
> +						 device_feature_select));
> +	pci_write_config_dword(dev, cfg + offsetof(struct virtio_pci_cfg_cap,
> +						  pci_cfg_data),
> +			       VIRTIO_F_IOMMU_PLATFORM / 32);
> +
> +	/* Get the features dword. */
> +	pci_write_config_dword(dev, cfg + offsetof(struct virtio_pci_cfg_cap,
> +						  cap.offset),
> +			       offset + offsetof(struct virtio_pci_common_cfg,
> +						 device_feature));
> +	pci_read_config_dword(dev, cfg + offsetof(struct virtio_pci_cfg_cap,
> +						  pci_cfg_data),
> +			      &features);
> +
> +	/* Does this device obey the platform's IOMMU? If not it's an error. */
> +	if (!(features & (0x1 << (VIRTIO_F_IOMMU_PLATFORM % 32)))) {
> +                dev_warn(&dev->dev,
> +                         "Virtio device lacks VIRTIO_F_IOMMU_PLATFORM.\n");

Whitespace

> +		return -ENODEV;
> +	}
> +
> +	return 0;
> +}
> diff --git a/drivers/vfio/pci/Makefile b/drivers/vfio/pci/Makefile
> index 76d8ec0..e9b20e7 100644
> --- a/drivers/vfio/pci/Makefile
> +++ b/drivers/vfio/pci/Makefile
> @@ -1,5 +1,6 @@
>  
>  vfio-pci-y := vfio_pci.o vfio_pci_intrs.o vfio_pci_rdwr.o vfio_pci_config.o
> +vfio-pci-y += vfio_pci_virtio.o
>  vfio-pci-$(CONFIG_VFIO_PCI_IGD) += vfio_pci_igd.o
>  
>  obj-$(CONFIG_VFIO_PCI) += vfio-pci.o

Thanks,
Alex
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Michael S. Tsirkin Aug. 30, 2016, 3:48 a.m. UTC | #2
On Mon, Aug 29, 2016 at 09:23:25PM -0600, Alex Williamson wrote:
> On Tue, 30 Aug 2016 05:27:17 +0300
> "Michael S. Tsirkin" <mst@redhat.com> wrote:
> 
> > Modern virtio pci devices can set VIRTIO_F_IOMMU_PLATFORM
> > to signal they are safe to use with an IOMMU.
> > 
> > Without this bit, exposing the device to userspace is unsafe, so probe
> > and fail VFIO initialization unless noiommu is enabled.
> > 
> > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> > ---
> >  drivers/vfio/pci/vfio_pci_private.h |   1 +
> >  drivers/vfio/pci/vfio_pci.c         |  14 ++++
> >  drivers/vfio/pci/vfio_pci_virtio.c  | 140 ++++++++++++++++++++++++++++++++++++
> >  drivers/vfio/pci/Makefile           |   1 +
> >  4 files changed, 156 insertions(+)
> >  create mode 100644 drivers/vfio/pci/vfio_pci_virtio.c
> > 
> > diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h
> > index 2128de8..2bd5616 100644
> > --- a/drivers/vfio/pci/vfio_pci_private.h
> > +++ b/drivers/vfio/pci/vfio_pci_private.h
> > @@ -139,4 +139,5 @@ static inline int vfio_pci_igd_init(struct vfio_pci_device *vdev)
> >  	return -ENODEV;
> >  }
> >  #endif
> > +extern int vfio_pci_virtio_quirk(struct vfio_pci_device *vdev, bool noiommu);
> >  #endif /* VFIO_PCI_PRIVATE_H */
> > diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> > index d624a52..e93bf0c 100644
> > --- a/drivers/vfio/pci/vfio_pci.c
> > +++ b/drivers/vfio/pci/vfio_pci.c
> > @@ -1236,6 +1236,20 @@ static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> >  		return ret;
> >  	}
> >  
> > +	if (pdev->vendor == PCI_VENDOR_ID_REDHAT_QUMRANET) {
> 
> Perhaps a vfio_pci_is_virtio() like vga below?  Let's test the device
> ID range initially as well, this test raised a big red flag for me
> whether all devices within this vendor ID were virtio.
> 
> > +		bool noiommu = vfio_is_noiommu_group_dev(&pdev->dev);
> 
> I think you can use iommu_present() for this and avoid patch 1of2.

So in presence of an IOMMU in the system, is it impossible to bind the
noiommu device?

I did not test this yet.

If yes this is something we'll need to fix as well -
we do want to allow binding noiommu to a legacy virtio device.



> noiommu is mutually exclusive to an iommu being present.  Seems like
> all of this logic should be in the quirk itself, I'm not sure what it
> buys to get the value here but wait until later to use it.  Using
> iommu_present() could also move this test much earlier in
> vfio_pci_probe() making the exit path easier.
> 
> > +
> > +		ret = vfio_pci_virtio_quirk(vdev, noiommu);
> > +		if (ret) {
> > +			dev_warn(&vdev->pdev->dev,
> > +				 "Failed to setup Virtio for VFIO\n");
> > +			vfio_del_group_dev(&pdev->dev);
> > +			vfio_iommu_group_put(group, &pdev->dev);
> > +			kfree(vdev);
> > +			return ret;
> > +		}
> > +	}
> > +
> >  	if (vfio_pci_is_vga(pdev)) {
> >  		vga_client_register(pdev, vdev, NULL, vfio_pci_set_vga_decode);
> >  		vga_set_legacy_decoding(pdev,
> > diff --git a/drivers/vfio/pci/vfio_pci_virtio.c b/drivers/vfio/pci/vfio_pci_virtio.c
> > new file mode 100644
> > index 0000000..e1ecffd
> > --- /dev/null
> > +++ b/drivers/vfio/pci/vfio_pci_virtio.c
> > @@ -0,0 +1,140 @@
> > +/*
> > + * VFIO PCI Intel Graphics support
>       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > + *
> > + * Copyright (C) 2016 Red Hat, Inc.  All rights reserved.
> > + *	Author: Alex Williamson <alex.williamson@redhat.com>
> 
> Update.
> 
> > + *
> > + * This program is free software; you can redistribute it and/or modify
> > + * it under the terms of the GNU General Public License version 2 as
> > + * published by the Free Software Foundation.
> > + *
> > + * Register a device specific region through which to provide read-only
> > + * access to the Intel IGD opregion.  The register defining the opregion
> > + * address is also virtualized to prevent user modification.
> > + */
> > +
> > +#include <linux/io.h>
> > +#include <linux/pci.h>
> > +#include <linux/uaccess.h>
> 
> Are io.h and uaccess.h needed?
> 
> > +#include <linux/vfio.h>
> > +#include <linux/virtio_pci.h>
> > +#include <linux/virtio_config.h>
> > +
> > +#include "vfio_pci_private.h"
> > +
> > +/**
> > + * virtio_pci_find_capability - walk capabilities to find device info.
> > + * @dev: the pci device
> > + * @cfg_type: the VIRTIO_PCI_CAP_* value we seek
> > + *
> > + * Returns offset of the capability, or 0.
> > + */
> > +static inline int virtio_pci_find_capability(struct pci_dev *dev, u8 cfg_type)
> 
> Does inlining this really make sense?
> 
> > +{
> > +	int pos;
> > +
> > +	for (pos = pci_find_capability(dev, PCI_CAP_ID_VNDR);
> > +	     pos > 0;
> > +	     pos = pci_find_next_capability(dev, pos, PCI_CAP_ID_VNDR)) {
> > +		u8 type;
> > +		pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
> > +							 cfg_type),
> > +				     &type);
> > +
> > +		if (type != cfg_type)
> > +			continue;
> > +
> > +		/* Ignore structures with reserved BAR values */
> > +		if (type != VIRTIO_PCI_CAP_PCI_CFG) {
> > +			u8 bar;
> > +
> > +			pci_read_config_byte(dev, pos +
> > +					     offsetof(struct virtio_pci_cap,
> > +						      bar),
> > +					     &bar);
> > +			if (bar > 0x5)
> 
> s/0x5/PCI_STD_RESOURCE_END/
> 
> > +				continue;
> > +		}
> > +
> > +		return pos;
> > +	}
> > +	return 0;
> > +}
> > +
> > +
> > +int vfio_pci_virtio_quirk(struct vfio_pci_device *vdev, bool noiommu)
> > +{
> > +	struct pci_dev *dev = vdev->pdev;
> 
> Please use *pdev for consistency with the rest of drivers/vfio/pci/*
> 
> Also, is there any reason to pass the vfio_pci_device?  There's nothing
> vfio here otherwise and we could remove more #includes.
> 
> > +	int common, cfg;
> > +	u32 features;
> > +	u32 offset;
> > +	u8 bar;
> > +
> > +	/* Without an IOMMU, we don't care */
> > +	if (noiommu)
> > +		return 0;
> > +
> > +        /* Virtio only owns devices >= 0x1000 and <= 0x107f: leave the rest. */
> > +        if (dev->device < 0x1000 || dev->device > 0x107f)
> > +                return 0;
> 
> Whitespace
> 
> > +
> > +	/* Check whether device enforces the IOMMU correctly */
> > +
> > +	/*
> > +	 * All modern devices must have common and cfg capabilities. We use cfg
> > +	 * capability for access so that we don't need to worry about resource
> > +	 * availability. Slow but sure.
> > +	 * Note that all vendor-specific fields we access are little-endian
> > +	 * which matches what pci config accessors expect, so they do byteswap
> > +	 * for us if appropriate.
> > +	 */
> > +	common = virtio_pci_find_capability(dev, VIRTIO_PCI_CAP_COMMON_CFG);
> > +	cfg = virtio_pci_find_capability(dev, VIRTIO_PCI_CAP_PCI_CFG);
> > +	if (!cfg || !common) {
> > +                dev_warn(&dev->dev,
> > +                         "Virtio device lacks common or pci cfg.\n");
> 
> Whitespace
> 
> > +		return -ENODEV;
> > +	}
> > +
> > +	pci_read_config_byte(dev, common + offsetof(struct virtio_pci_cap,
> > +						    bar),
> > +			     &bar);
> > +	pci_read_config_dword(dev, common + offsetof(struct virtio_pci_cap,
> > +						    offset),
> > +			     &offset);
> > +
> > +	/* Program cfg capability for dword access into common cfg. */
> > +	pci_write_config_byte(dev, cfg + offsetof(struct virtio_pci_cfg_cap,
> > +						  cap.bar),
> > +			      bar);
> > +	pci_write_config_dword(dev, cfg + offsetof(struct virtio_pci_cfg_cap,
> > +						   cap.length),
> > +			       0x4);
> > +
> > +	/* Select features dword that has VIRTIO_F_IOMMU_PLATFORM. */
> > +	pci_write_config_dword(dev, cfg + offsetof(struct virtio_pci_cfg_cap,
> > +						  cap.offset),
> > +			       offset + offsetof(struct virtio_pci_common_cfg,
> > +						 device_feature_select));
> > +	pci_write_config_dword(dev, cfg + offsetof(struct virtio_pci_cfg_cap,
> > +						  pci_cfg_data),
> > +			       VIRTIO_F_IOMMU_PLATFORM / 32);
> > +
> > +	/* Get the features dword. */
> > +	pci_write_config_dword(dev, cfg + offsetof(struct virtio_pci_cfg_cap,
> > +						  cap.offset),
> > +			       offset + offsetof(struct virtio_pci_common_cfg,
> > +						 device_feature));
> > +	pci_read_config_dword(dev, cfg + offsetof(struct virtio_pci_cfg_cap,
> > +						  pci_cfg_data),
> > +			      &features);
> > +
> > +	/* Does this device obey the platform's IOMMU? If not it's an error. */
> > +	if (!(features & (0x1 << (VIRTIO_F_IOMMU_PLATFORM % 32)))) {
> > +                dev_warn(&dev->dev,
> > +                         "Virtio device lacks VIRTIO_F_IOMMU_PLATFORM.\n");
> 
> Whitespace
> 
> > +		return -ENODEV;
> > +	}
> > +
> > +	return 0;
> > +}
> > diff --git a/drivers/vfio/pci/Makefile b/drivers/vfio/pci/Makefile
> > index 76d8ec0..e9b20e7 100644
> > --- a/drivers/vfio/pci/Makefile
> > +++ b/drivers/vfio/pci/Makefile
> > @@ -1,5 +1,6 @@
> >  
> >  vfio-pci-y := vfio_pci.o vfio_pci_intrs.o vfio_pci_rdwr.o vfio_pci_config.o
> > +vfio-pci-y += vfio_pci_virtio.o
> >  vfio-pci-$(CONFIG_VFIO_PCI_IGD) += vfio_pci_igd.o
> >  
> >  obj-$(CONFIG_VFIO_PCI) += vfio-pci.o
> 
> Thanks,
> Alex
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Alex Williamson Aug. 30, 2016, 3:52 a.m. UTC | #3
On Mon, 29 Aug 2016 21:23:25 -0600
Alex Williamson <alex.williamson@redhat.com> wrote:

> On Tue, 30 Aug 2016 05:27:17 +0300
> "Michael S. Tsirkin" <mst@redhat.com> wrote:
> 
> > Modern virtio pci devices can set VIRTIO_F_IOMMU_PLATFORM
> > to signal they are safe to use with an IOMMU.
> > 
> > Without this bit, exposing the device to userspace is unsafe, so probe
> > and fail VFIO initialization unless noiommu is enabled.
> > 
> > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> > ---
> >  drivers/vfio/pci/vfio_pci_private.h |   1 +
> >  drivers/vfio/pci/vfio_pci.c         |  14 ++++
> >  drivers/vfio/pci/vfio_pci_virtio.c  | 140 ++++++++++++++++++++++++++++++++++++
> >  drivers/vfio/pci/Makefile           |   1 +
> >  4 files changed, 156 insertions(+)
> >  create mode 100644 drivers/vfio/pci/vfio_pci_virtio.c
> > 
> > diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h
> > index 2128de8..2bd5616 100644
> > --- a/drivers/vfio/pci/vfio_pci_private.h
> > +++ b/drivers/vfio/pci/vfio_pci_private.h
> > @@ -139,4 +139,5 @@ static inline int vfio_pci_igd_init(struct vfio_pci_device *vdev)
> >  	return -ENODEV;
> >  }
> >  #endif
> > +extern int vfio_pci_virtio_quirk(struct vfio_pci_device *vdev, bool noiommu);
> >  #endif /* VFIO_PCI_PRIVATE_H */
> > diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> > index d624a52..e93bf0c 100644
> > --- a/drivers/vfio/pci/vfio_pci.c
> > +++ b/drivers/vfio/pci/vfio_pci.c
> > @@ -1236,6 +1236,20 @@ static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> >  		return ret;
> >  	}
> >  
> > +	if (pdev->vendor == PCI_VENDOR_ID_REDHAT_QUMRANET) {  
> 
> Perhaps a vfio_pci_is_virtio() like vga below?  Let's test the device
> ID range initially as well, this test raised a big red flag for me
> whether all devices within this vendor ID were virtio.
> 
> > +		bool noiommu = vfio_is_noiommu_group_dev(&pdev->dev);  
> 
> I think you can use iommu_present() for this and avoid patch 1of2.
> noiommu is mutually exclusive to an iommu being present.  Seems like
> all of this logic should be in the quirk itself, I'm not sure what it
> buys to get the value here but wait until later to use it.  Using
> iommu_present() could also move this test much earlier in
> vfio_pci_probe() making the exit path easier.

Except then I'm reintroducing the bug fixed by 16ab8a5cbea4 since
iommu_present() assumes an IOMMU API based device.  I'll try to think if
there's another way to avoid adding the is_noiommu function.  Thanks,

Alex

> 
> > +
> > +		ret = vfio_pci_virtio_quirk(vdev, noiommu);
> > +		if (ret) {
> > +			dev_warn(&vdev->pdev->dev,
> > +				 "Failed to setup Virtio for VFIO\n");
> > +			vfio_del_group_dev(&pdev->dev);
> > +			vfio_iommu_group_put(group, &pdev->dev);
> > +			kfree(vdev);
> > +			return ret;
> > +		}
> > +	}
> > +
> >  	if (vfio_pci_is_vga(pdev)) {
> >  		vga_client_register(pdev, vdev, NULL, vfio_pci_set_vga_decode);
> >  		vga_set_legacy_decoding(pdev,
> > diff --git a/drivers/vfio/pci/vfio_pci_virtio.c b/drivers/vfio/pci/vfio_pci_virtio.c
> > new file mode 100644
> > index 0000000..e1ecffd
> > --- /dev/null
> > +++ b/drivers/vfio/pci/vfio_pci_virtio.c
> > @@ -0,0 +1,140 @@
> > +/*
> > + * VFIO PCI Intel Graphics support  
>       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > + *
> > + * Copyright (C) 2016 Red Hat, Inc.  All rights reserved.
> > + *	Author: Alex Williamson <alex.williamson@redhat.com>  
> 
> Update.
> 
> > + *
> > + * This program is free software; you can redistribute it and/or modify
> > + * it under the terms of the GNU General Public License version 2 as
> > + * published by the Free Software Foundation.
> > + *
> > + * Register a device specific region through which to provide read-only
> > + * access to the Intel IGD opregion.  The register defining the opregion
> > + * address is also virtualized to prevent user modification.
> > + */
> > +
> > +#include <linux/io.h>
> > +#include <linux/pci.h>
> > +#include <linux/uaccess.h>  
> 
> Are io.h and uaccess.h needed?
> 
> > +#include <linux/vfio.h>
> > +#include <linux/virtio_pci.h>
> > +#include <linux/virtio_config.h>
> > +
> > +#include "vfio_pci_private.h"
> > +
> > +/**
> > + * virtio_pci_find_capability - walk capabilities to find device info.
> > + * @dev: the pci device
> > + * @cfg_type: the VIRTIO_PCI_CAP_* value we seek
> > + *
> > + * Returns offset of the capability, or 0.
> > + */
> > +static inline int virtio_pci_find_capability(struct pci_dev *dev, u8 cfg_type)  
> 
> Does inlining this really make sense?
> 
> > +{
> > +	int pos;
> > +
> > +	for (pos = pci_find_capability(dev, PCI_CAP_ID_VNDR);
> > +	     pos > 0;
> > +	     pos = pci_find_next_capability(dev, pos, PCI_CAP_ID_VNDR)) {
> > +		u8 type;
> > +		pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
> > +							 cfg_type),
> > +				     &type);
> > +
> > +		if (type != cfg_type)
> > +			continue;
> > +
> > +		/* Ignore structures with reserved BAR values */
> > +		if (type != VIRTIO_PCI_CAP_PCI_CFG) {
> > +			u8 bar;
> > +
> > +			pci_read_config_byte(dev, pos +
> > +					     offsetof(struct virtio_pci_cap,
> > +						      bar),
> > +					     &bar);
> > +			if (bar > 0x5)  
> 
> s/0x5/PCI_STD_RESOURCE_END/
> 
> > +				continue;
> > +		}
> > +
> > +		return pos;
> > +	}
> > +	return 0;
> > +}
> > +
> > +
> > +int vfio_pci_virtio_quirk(struct vfio_pci_device *vdev, bool noiommu)
> > +{
> > +	struct pci_dev *dev = vdev->pdev;  
> 
> Please use *pdev for consistency with the rest of drivers/vfio/pci/*
> 
> Also, is there any reason to pass the vfio_pci_device?  There's nothing
> vfio here otherwise and we could remove more #includes.
> 
> > +	int common, cfg;
> > +	u32 features;
> > +	u32 offset;
> > +	u8 bar;
> > +
> > +	/* Without an IOMMU, we don't care */
> > +	if (noiommu)
> > +		return 0;
> > +
> > +        /* Virtio only owns devices >= 0x1000 and <= 0x107f: leave the rest. */
> > +        if (dev->device < 0x1000 || dev->device > 0x107f)
> > +                return 0;  
> 
> Whitespace
> 
> > +
> > +	/* Check whether device enforces the IOMMU correctly */
> > +
> > +	/*
> > +	 * All modern devices must have common and cfg capabilities. We use cfg
> > +	 * capability for access so that we don't need to worry about resource
> > +	 * availability. Slow but sure.
> > +	 * Note that all vendor-specific fields we access are little-endian
> > +	 * which matches what pci config accessors expect, so they do byteswap
> > +	 * for us if appropriate.
> > +	 */
> > +	common = virtio_pci_find_capability(dev, VIRTIO_PCI_CAP_COMMON_CFG);
> > +	cfg = virtio_pci_find_capability(dev, VIRTIO_PCI_CAP_PCI_CFG);
> > +	if (!cfg || !common) {
> > +                dev_warn(&dev->dev,
> > +                         "Virtio device lacks common or pci cfg.\n");  
> 
> Whitespace
> 
> > +		return -ENODEV;
> > +	}
> > +
> > +	pci_read_config_byte(dev, common + offsetof(struct virtio_pci_cap,
> > +						    bar),
> > +			     &bar);
> > +	pci_read_config_dword(dev, common + offsetof(struct virtio_pci_cap,
> > +						    offset),
> > +			     &offset);
> > +
> > +	/* Program cfg capability for dword access into common cfg. */
> > +	pci_write_config_byte(dev, cfg + offsetof(struct virtio_pci_cfg_cap,
> > +						  cap.bar),
> > +			      bar);
> > +	pci_write_config_dword(dev, cfg + offsetof(struct virtio_pci_cfg_cap,
> > +						   cap.length),
> > +			       0x4);
> > +
> > +	/* Select features dword that has VIRTIO_F_IOMMU_PLATFORM. */
> > +	pci_write_config_dword(dev, cfg + offsetof(struct virtio_pci_cfg_cap,
> > +						  cap.offset),
> > +			       offset + offsetof(struct virtio_pci_common_cfg,
> > +						 device_feature_select));
> > +	pci_write_config_dword(dev, cfg + offsetof(struct virtio_pci_cfg_cap,
> > +						  pci_cfg_data),
> > +			       VIRTIO_F_IOMMU_PLATFORM / 32);
> > +
> > +	/* Get the features dword. */
> > +	pci_write_config_dword(dev, cfg + offsetof(struct virtio_pci_cfg_cap,
> > +						  cap.offset),
> > +			       offset + offsetof(struct virtio_pci_common_cfg,
> > +						 device_feature));
> > +	pci_read_config_dword(dev, cfg + offsetof(struct virtio_pci_cfg_cap,
> > +						  pci_cfg_data),
> > +			      &features);
> > +
> > +	/* Does this device obey the platform's IOMMU? If not it's an error. */
> > +	if (!(features & (0x1 << (VIRTIO_F_IOMMU_PLATFORM % 32)))) {
> > +                dev_warn(&dev->dev,
> > +                         "Virtio device lacks VIRTIO_F_IOMMU_PLATFORM.\n");  
> 
> Whitespace
> 
> > +		return -ENODEV;
> > +	}
> > +
> > +	return 0;
> > +}
> > diff --git a/drivers/vfio/pci/Makefile b/drivers/vfio/pci/Makefile
> > index 76d8ec0..e9b20e7 100644
> > --- a/drivers/vfio/pci/Makefile
> > +++ b/drivers/vfio/pci/Makefile
> > @@ -1,5 +1,6 @@
> >  
> >  vfio-pci-y := vfio_pci.o vfio_pci_intrs.o vfio_pci_rdwr.o vfio_pci_config.o
> > +vfio-pci-y += vfio_pci_virtio.o
> >  vfio-pci-$(CONFIG_VFIO_PCI_IGD) += vfio_pci_igd.o
> >  
> >  obj-$(CONFIG_VFIO_PCI) += vfio-pci.o  
> 
> Thanks,
> Alex
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Michael S. Tsirkin Aug. 30, 2016, 3:57 a.m. UTC | #4
On Mon, Aug 29, 2016 at 09:52:20PM -0600, Alex Williamson wrote:
> On Mon, 29 Aug 2016 21:23:25 -0600
> Alex Williamson <alex.williamson@redhat.com> wrote:
> 
> > On Tue, 30 Aug 2016 05:27:17 +0300
> > "Michael S. Tsirkin" <mst@redhat.com> wrote:
> > 
> > > Modern virtio pci devices can set VIRTIO_F_IOMMU_PLATFORM
> > > to signal they are safe to use with an IOMMU.
> > > 
> > > Without this bit, exposing the device to userspace is unsafe, so probe
> > > and fail VFIO initialization unless noiommu is enabled.
> > > 
> > > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> > > ---
> > >  drivers/vfio/pci/vfio_pci_private.h |   1 +
> > >  drivers/vfio/pci/vfio_pci.c         |  14 ++++
> > >  drivers/vfio/pci/vfio_pci_virtio.c  | 140 ++++++++++++++++++++++++++++++++++++
> > >  drivers/vfio/pci/Makefile           |   1 +
> > >  4 files changed, 156 insertions(+)
> > >  create mode 100644 drivers/vfio/pci/vfio_pci_virtio.c
> > > 
> > > diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h
> > > index 2128de8..2bd5616 100644
> > > --- a/drivers/vfio/pci/vfio_pci_private.h
> > > +++ b/drivers/vfio/pci/vfio_pci_private.h
> > > @@ -139,4 +139,5 @@ static inline int vfio_pci_igd_init(struct vfio_pci_device *vdev)
> > >  	return -ENODEV;
> > >  }
> > >  #endif
> > > +extern int vfio_pci_virtio_quirk(struct vfio_pci_device *vdev, bool noiommu);
> > >  #endif /* VFIO_PCI_PRIVATE_H */
> > > diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> > > index d624a52..e93bf0c 100644
> > > --- a/drivers/vfio/pci/vfio_pci.c
> > > +++ b/drivers/vfio/pci/vfio_pci.c
> > > @@ -1236,6 +1236,20 @@ static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> > >  		return ret;
> > >  	}
> > >  
> > > +	if (pdev->vendor == PCI_VENDOR_ID_REDHAT_QUMRANET) {  
> > 
> > Perhaps a vfio_pci_is_virtio() like vga below?  Let's test the device
> > ID range initially as well, this test raised a big red flag for me
> > whether all devices within this vendor ID were virtio.
> > 
> > > +		bool noiommu = vfio_is_noiommu_group_dev(&pdev->dev);  
> > 
> > I think you can use iommu_present() for this and avoid patch 1of2.
> > noiommu is mutually exclusive to an iommu being present.  Seems like
> > all of this logic should be in the quirk itself, I'm not sure what it
> > buys to get the value here but wait until later to use it.  Using
> > iommu_present() could also move this test much earlier in
> > vfio_pci_probe() making the exit path easier.
> 
> Except then I'm reintroducing the bug fixed by 16ab8a5cbea4 since
> iommu_present() assumes an IOMMU API based device.  I'll try to think if
> there's another way to avoid adding the is_noiommu function.  Thanks,
> 
> Alex

FWIW I'm only too happy if you take over this patch.
You need Jason's recent patchset to QEMU to test,
but otherwise no special hardware is required.

> > 
> > > +
> > > +		ret = vfio_pci_virtio_quirk(vdev, noiommu);
> > > +		if (ret) {
> > > +			dev_warn(&vdev->pdev->dev,
> > > +				 "Failed to setup Virtio for VFIO\n");
> > > +			vfio_del_group_dev(&pdev->dev);
> > > +			vfio_iommu_group_put(group, &pdev->dev);
> > > +			kfree(vdev);
> > > +			return ret;
> > > +		}
> > > +	}
> > > +
> > >  	if (vfio_pci_is_vga(pdev)) {
> > >  		vga_client_register(pdev, vdev, NULL, vfio_pci_set_vga_decode);
> > >  		vga_set_legacy_decoding(pdev,
> > > diff --git a/drivers/vfio/pci/vfio_pci_virtio.c b/drivers/vfio/pci/vfio_pci_virtio.c
> > > new file mode 100644
> > > index 0000000..e1ecffd
> > > --- /dev/null
> > > +++ b/drivers/vfio/pci/vfio_pci_virtio.c
> > > @@ -0,0 +1,140 @@
> > > +/*
> > > + * VFIO PCI Intel Graphics support  
> >       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > > + *
> > > + * Copyright (C) 2016 Red Hat, Inc.  All rights reserved.
> > > + *	Author: Alex Williamson <alex.williamson@redhat.com>  
> > 
> > Update.
> > 
> > > + *
> > > + * This program is free software; you can redistribute it and/or modify
> > > + * it under the terms of the GNU General Public License version 2 as
> > > + * published by the Free Software Foundation.
> > > + *
> > > + * Register a device specific region through which to provide read-only
> > > + * access to the Intel IGD opregion.  The register defining the opregion
> > > + * address is also virtualized to prevent user modification.
> > > + */
> > > +
> > > +#include <linux/io.h>
> > > +#include <linux/pci.h>
> > > +#include <linux/uaccess.h>  
> > 
> > Are io.h and uaccess.h needed?
> > 
> > > +#include <linux/vfio.h>
> > > +#include <linux/virtio_pci.h>
> > > +#include <linux/virtio_config.h>
> > > +
> > > +#include "vfio_pci_private.h"
> > > +
> > > +/**
> > > + * virtio_pci_find_capability - walk capabilities to find device info.
> > > + * @dev: the pci device
> > > + * @cfg_type: the VIRTIO_PCI_CAP_* value we seek
> > > + *
> > > + * Returns offset of the capability, or 0.
> > > + */
> > > +static inline int virtio_pci_find_capability(struct pci_dev *dev, u8 cfg_type)  
> > 
> > Does inlining this really make sense?
> > 
> > > +{
> > > +	int pos;
> > > +
> > > +	for (pos = pci_find_capability(dev, PCI_CAP_ID_VNDR);
> > > +	     pos > 0;
> > > +	     pos = pci_find_next_capability(dev, pos, PCI_CAP_ID_VNDR)) {
> > > +		u8 type;
> > > +		pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
> > > +							 cfg_type),
> > > +				     &type);
> > > +
> > > +		if (type != cfg_type)
> > > +			continue;
> > > +
> > > +		/* Ignore structures with reserved BAR values */
> > > +		if (type != VIRTIO_PCI_CAP_PCI_CFG) {
> > > +			u8 bar;
> > > +
> > > +			pci_read_config_byte(dev, pos +
> > > +					     offsetof(struct virtio_pci_cap,
> > > +						      bar),
> > > +					     &bar);
> > > +			if (bar > 0x5)  
> > 
> > s/0x5/PCI_STD_RESOURCE_END/
> > 
> > > +				continue;
> > > +		}
> > > +
> > > +		return pos;
> > > +	}
> > > +	return 0;
> > > +}
> > > +
> > > +
> > > +int vfio_pci_virtio_quirk(struct vfio_pci_device *vdev, bool noiommu)
> > > +{
> > > +	struct pci_dev *dev = vdev->pdev;  
> > 
> > Please use *pdev for consistency with the rest of drivers/vfio/pci/*
> > 
> > Also, is there any reason to pass the vfio_pci_device?  There's nothing
> > vfio here otherwise and we could remove more #includes.
> > 
> > > +	int common, cfg;
> > > +	u32 features;
> > > +	u32 offset;
> > > +	u8 bar;
> > > +
> > > +	/* Without an IOMMU, we don't care */
> > > +	if (noiommu)
> > > +		return 0;
> > > +
> > > +        /* Virtio only owns devices >= 0x1000 and <= 0x107f: leave the rest. */
> > > +        if (dev->device < 0x1000 || dev->device > 0x107f)
> > > +                return 0;  
> > 
> > Whitespace
> > 
> > > +
> > > +	/* Check whether device enforces the IOMMU correctly */
> > > +
> > > +	/*
> > > +	 * All modern devices must have common and cfg capabilities. We use cfg
> > > +	 * capability for access so that we don't need to worry about resource
> > > +	 * availability. Slow but sure.
> > > +	 * Note that all vendor-specific fields we access are little-endian
> > > +	 * which matches what pci config accessors expect, so they do byteswap
> > > +	 * for us if appropriate.
> > > +	 */
> > > +	common = virtio_pci_find_capability(dev, VIRTIO_PCI_CAP_COMMON_CFG);
> > > +	cfg = virtio_pci_find_capability(dev, VIRTIO_PCI_CAP_PCI_CFG);
> > > +	if (!cfg || !common) {
> > > +                dev_warn(&dev->dev,
> > > +                         "Virtio device lacks common or pci cfg.\n");  
> > 
> > Whitespace
> > 
> > > +		return -ENODEV;
> > > +	}
> > > +
> > > +	pci_read_config_byte(dev, common + offsetof(struct virtio_pci_cap,
> > > +						    bar),
> > > +			     &bar);
> > > +	pci_read_config_dword(dev, common + offsetof(struct virtio_pci_cap,
> > > +						    offset),
> > > +			     &offset);
> > > +
> > > +	/* Program cfg capability for dword access into common cfg. */
> > > +	pci_write_config_byte(dev, cfg + offsetof(struct virtio_pci_cfg_cap,
> > > +						  cap.bar),
> > > +			      bar);
> > > +	pci_write_config_dword(dev, cfg + offsetof(struct virtio_pci_cfg_cap,
> > > +						   cap.length),
> > > +			       0x4);
> > > +
> > > +	/* Select features dword that has VIRTIO_F_IOMMU_PLATFORM. */
> > > +	pci_write_config_dword(dev, cfg + offsetof(struct virtio_pci_cfg_cap,
> > > +						  cap.offset),
> > > +			       offset + offsetof(struct virtio_pci_common_cfg,
> > > +						 device_feature_select));
> > > +	pci_write_config_dword(dev, cfg + offsetof(struct virtio_pci_cfg_cap,
> > > +						  pci_cfg_data),
> > > +			       VIRTIO_F_IOMMU_PLATFORM / 32);
> > > +
> > > +	/* Get the features dword. */
> > > +	pci_write_config_dword(dev, cfg + offsetof(struct virtio_pci_cfg_cap,
> > > +						  cap.offset),
> > > +			       offset + offsetof(struct virtio_pci_common_cfg,
> > > +						 device_feature));
> > > +	pci_read_config_dword(dev, cfg + offsetof(struct virtio_pci_cfg_cap,
> > > +						  pci_cfg_data),
> > > +			      &features);
> > > +
> > > +	/* Does this device obey the platform's IOMMU? If not it's an error. */
> > > +	if (!(features & (0x1 << (VIRTIO_F_IOMMU_PLATFORM % 32)))) {
> > > +                dev_warn(&dev->dev,
> > > +                         "Virtio device lacks VIRTIO_F_IOMMU_PLATFORM.\n");  
> > 
> > Whitespace
> > 
> > > +		return -ENODEV;
> > > +	}
> > > +
> > > +	return 0;
> > > +}
> > > diff --git a/drivers/vfio/pci/Makefile b/drivers/vfio/pci/Makefile
> > > index 76d8ec0..e9b20e7 100644
> > > --- a/drivers/vfio/pci/Makefile
> > > +++ b/drivers/vfio/pci/Makefile
> > > @@ -1,5 +1,6 @@
> > >  
> > >  vfio-pci-y := vfio_pci.o vfio_pci_intrs.o vfio_pci_rdwr.o vfio_pci_config.o
> > > +vfio-pci-y += vfio_pci_virtio.o
> > >  vfio-pci-$(CONFIG_VFIO_PCI_IGD) += vfio_pci_igd.o
> > >  
> > >  obj-$(CONFIG_VFIO_PCI) += vfio-pci.o  
> > 
> > Thanks,
> > Alex
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kernel test robot Aug. 30, 2016, 9:59 a.m. UTC | #5
Hi Michael,

[auto build test ERROR on vfio/next]
[also build test ERROR on v4.8-rc4 next-20160825]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
[Suggest to use git(>=2.9.0) format-patch --base=<commit> (or --base=auto for convenience) to record what (public, well-known) commit your patch series was built on]
[Check https://git-scm.com/docs/git-format-patch for more information]

url:    https://github.com/0day-ci/linux/commits/Michael-S-Tsirkin/vfio-blacklist-legacy-virtio-devices/20160830-124010
base:   https://github.com/awilliam/linux-vfio.git next
config: x86_64-rhel (attached as .config)
compiler: gcc-6 (Debian 6.1.1-9) 6.1.1 20160705
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

All errors (new ones prefixed by >>):

>> ERROR: "vfio_is_noiommu_group_dev" [drivers/vfio/pci/vfio-pci.ko] undefined!

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

Patch
diff mbox

diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h
index 2128de8..2bd5616 100644
--- a/drivers/vfio/pci/vfio_pci_private.h
+++ b/drivers/vfio/pci/vfio_pci_private.h
@@ -139,4 +139,5 @@  static inline int vfio_pci_igd_init(struct vfio_pci_device *vdev)
 	return -ENODEV;
 }
 #endif
+extern int vfio_pci_virtio_quirk(struct vfio_pci_device *vdev, bool noiommu);
 #endif /* VFIO_PCI_PRIVATE_H */
diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index d624a52..e93bf0c 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -1236,6 +1236,20 @@  static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 		return ret;
 	}
 
+	if (pdev->vendor == PCI_VENDOR_ID_REDHAT_QUMRANET) {
+		bool noiommu = vfio_is_noiommu_group_dev(&pdev->dev);
+
+		ret = vfio_pci_virtio_quirk(vdev, noiommu);
+		if (ret) {
+			dev_warn(&vdev->pdev->dev,
+				 "Failed to setup Virtio for VFIO\n");
+			vfio_del_group_dev(&pdev->dev);
+			vfio_iommu_group_put(group, &pdev->dev);
+			kfree(vdev);
+			return ret;
+		}
+	}
+
 	if (vfio_pci_is_vga(pdev)) {
 		vga_client_register(pdev, vdev, NULL, vfio_pci_set_vga_decode);
 		vga_set_legacy_decoding(pdev,
diff --git a/drivers/vfio/pci/vfio_pci_virtio.c b/drivers/vfio/pci/vfio_pci_virtio.c
new file mode 100644
index 0000000..e1ecffd
--- /dev/null
+++ b/drivers/vfio/pci/vfio_pci_virtio.c
@@ -0,0 +1,140 @@ 
+/*
+ * VFIO PCI Intel Graphics support
+ *
+ * Copyright (C) 2016 Red Hat, Inc.  All rights reserved.
+ *	Author: Alex Williamson <alex.williamson@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * Register a device specific region through which to provide read-only
+ * access to the Intel IGD opregion.  The register defining the opregion
+ * address is also virtualized to prevent user modification.
+ */
+
+#include <linux/io.h>
+#include <linux/pci.h>
+#include <linux/uaccess.h>
+#include <linux/vfio.h>
+#include <linux/virtio_pci.h>
+#include <linux/virtio_config.h>
+
+#include "vfio_pci_private.h"
+
+/**
+ * virtio_pci_find_capability - walk capabilities to find device info.
+ * @dev: the pci device
+ * @cfg_type: the VIRTIO_PCI_CAP_* value we seek
+ *
+ * Returns offset of the capability, or 0.
+ */
+static inline int virtio_pci_find_capability(struct pci_dev *dev, u8 cfg_type)
+{
+	int pos;
+
+	for (pos = pci_find_capability(dev, PCI_CAP_ID_VNDR);
+	     pos > 0;
+	     pos = pci_find_next_capability(dev, pos, PCI_CAP_ID_VNDR)) {
+		u8 type;
+		pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
+							 cfg_type),
+				     &type);
+
+		if (type != cfg_type)
+			continue;
+
+		/* Ignore structures with reserved BAR values */
+		if (type != VIRTIO_PCI_CAP_PCI_CFG) {
+			u8 bar;
+
+			pci_read_config_byte(dev, pos +
+					     offsetof(struct virtio_pci_cap,
+						      bar),
+					     &bar);
+			if (bar > 0x5)
+				continue;
+		}
+
+		return pos;
+	}
+	return 0;
+}
+
+
+int vfio_pci_virtio_quirk(struct vfio_pci_device *vdev, bool noiommu)
+{
+	struct pci_dev *dev = vdev->pdev;
+	int common, cfg;
+	u32 features;
+	u32 offset;
+	u8 bar;
+
+	/* Without an IOMMU, we don't care */
+	if (noiommu)
+		return 0;
+
+        /* Virtio only owns devices >= 0x1000 and <= 0x107f: leave the rest. */
+        if (dev->device < 0x1000 || dev->device > 0x107f)
+                return 0;
+
+	/* Check whether device enforces the IOMMU correctly */
+
+	/*
+	 * All modern devices must have common and cfg capabilities. We use cfg
+	 * capability for access so that we don't need to worry about resource
+	 * availability. Slow but sure.
+	 * Note that all vendor-specific fields we access are little-endian
+	 * which matches what pci config accessors expect, so they do byteswap
+	 * for us if appropriate.
+	 */
+	common = virtio_pci_find_capability(dev, VIRTIO_PCI_CAP_COMMON_CFG);
+	cfg = virtio_pci_find_capability(dev, VIRTIO_PCI_CAP_PCI_CFG);
+	if (!cfg || !common) {
+                dev_warn(&dev->dev,
+                         "Virtio device lacks common or pci cfg.\n");
+		return -ENODEV;
+	}
+
+	pci_read_config_byte(dev, common + offsetof(struct virtio_pci_cap,
+						    bar),
+			     &bar);
+	pci_read_config_dword(dev, common + offsetof(struct virtio_pci_cap,
+						    offset),
+			     &offset);
+
+	/* Program cfg capability for dword access into common cfg. */
+	pci_write_config_byte(dev, cfg + offsetof(struct virtio_pci_cfg_cap,
+						  cap.bar),
+			      bar);
+	pci_write_config_dword(dev, cfg + offsetof(struct virtio_pci_cfg_cap,
+						   cap.length),
+			       0x4);
+
+	/* Select features dword that has VIRTIO_F_IOMMU_PLATFORM. */
+	pci_write_config_dword(dev, cfg + offsetof(struct virtio_pci_cfg_cap,
+						  cap.offset),
+			       offset + offsetof(struct virtio_pci_common_cfg,
+						 device_feature_select));
+	pci_write_config_dword(dev, cfg + offsetof(struct virtio_pci_cfg_cap,
+						  pci_cfg_data),
+			       VIRTIO_F_IOMMU_PLATFORM / 32);
+
+	/* Get the features dword. */
+	pci_write_config_dword(dev, cfg + offsetof(struct virtio_pci_cfg_cap,
+						  cap.offset),
+			       offset + offsetof(struct virtio_pci_common_cfg,
+						 device_feature));
+	pci_read_config_dword(dev, cfg + offsetof(struct virtio_pci_cfg_cap,
+						  pci_cfg_data),
+			      &features);
+
+	/* Does this device obey the platform's IOMMU? If not it's an error. */
+	if (!(features & (0x1 << (VIRTIO_F_IOMMU_PLATFORM % 32)))) {
+                dev_warn(&dev->dev,
+                         "Virtio device lacks VIRTIO_F_IOMMU_PLATFORM.\n");
+		return -ENODEV;
+	}
+
+	return 0;
+}
diff --git a/drivers/vfio/pci/Makefile b/drivers/vfio/pci/Makefile
index 76d8ec0..e9b20e7 100644
--- a/drivers/vfio/pci/Makefile
+++ b/drivers/vfio/pci/Makefile
@@ -1,5 +1,6 @@ 
 
 vfio-pci-y := vfio_pci.o vfio_pci_intrs.o vfio_pci_rdwr.o vfio_pci_config.o
+vfio-pci-y += vfio_pci_virtio.o
 vfio-pci-$(CONFIG_VFIO_PCI_IGD) += vfio_pci_igd.o
 
 obj-$(CONFIG_VFIO_PCI) += vfio-pci.o