[PATCH V3] vfio: platform: support No-IOMMU mode

[PATCH V3] vfio: platform: support No-IOMMU mode

[Peng Fan]

The vfio No-IOMMU mode was supported by this
'commit 03a76b60f8ba2797 ("vfio: Include No-IOMMU mode")',
but it only support vfio-pci.

Using vfio_iommu_group_get/put, but not iommu_group_get/put,
the platform devices can be exposed to userspace with
CONFIG_VFIO_NOIOMMU and the "enable_unsafe_noiommu_mode"
option enabled.

>From 'commit 03a76b60f8ba2797 ("vfio: Include No-IOMMU mode")',
"This should make it very clear that this mode is not safe.
Additionally, CAP_SYS_RAWIO privileges are necessary to work
with groups and containers using this mode.  Groups making
use of this support are named /dev/vfio/noiommu-$GROUP and
can only make use of the special VFIO_NOIOMMU_IOMMU for the
container.  Use of this mode, specifically binding a device
without a native IOMMU group to a VFIO bus driver will taint
the kernel and should therefore not be considered supported."

Signed-off-by: Peng Fan <van.freenix@gmail.com>
Cc: Eric Auger <eric.auger@linaro.org>
Cc: Baptiste Reynal <b.reynal@virtualopensystems.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
---

V3:
 The platform device can be programmed to do DMA without
 caring out mmap + VFIO_IOMMU_MAP_DMA which are not
 support by noiommu. So drop the last sentence of commit log
 in V2, which is misleading.

V2:
 Rename subject to support No-IOMMU
 Add more commit log.
 I wrote a simple program following this
 https://github.com/virtualopensystems/vfio-host-test/blob/master/src_test/vfio_device_test.c
 ,no dma support. The device's register can be
 accessed in userspace using command './vfio_dev_test 30b60000.usdhc 0 1 platform'

 drivers/vfio/platform/vfio_platform_common.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
index e65b142..993b2f9 100644
--- a/drivers/vfio/platform/vfio_platform_common.c
+++ b/drivers/vfio/platform/vfio_platform_common.c
@@ -561,7 +561,7 @@ int vfio_platform_probe_common(struct vfio_platform_device *vdev,
 
 	vdev->device = dev;
 
-	group = iommu_group_get(dev);
+	group = vfio_iommu_group_get(dev);
 	if (!group) {
 		pr_err("VFIO: No IOMMU group for device %s\n", vdev->name);
 		return -EINVAL;
@@ -569,7 +569,7 @@ int vfio_platform_probe_common(struct vfio_platform_device *vdev,
 
 	ret = vfio_add_group_dev(dev, &vfio_platform_ops, vdev);
 	if (ret) {
-		iommu_group_put(group);
+		vfio_iommu_group_put(group, dev);
 		return ret;
 	}
 
@@ -589,7 +589,7 @@ struct vfio_platform_device *vfio_platform_remove_common(struct device *dev)
 
 	if (vdev) {
 		vfio_platform_put_reset(vdev);
-		iommu_group_put(dev->iommu_group);
+		vfio_iommu_group_put(dev->iommu_group, dev);
 	}
 
 	return vdev;
-- 
2.6.2

Re: [PATCH V3] vfio: platform: support No-IOMMU mode

[Peng Fan]

Hi,

Kindly ping.. Any comments on V3?

Thanks,
Peng.
On Mon, May 23, 2016 at 05:47:30PM +0800, Peng Fan wrote:
>The vfio No-IOMMU mode was supported by this
>'commit 03a76b60f8ba2797 ("vfio: Include No-IOMMU mode")',
>but it only support vfio-pci.
>
>Using vfio_iommu_group_get/put, but not iommu_group_get/put,
>the platform devices can be exposed to userspace with
>CONFIG_VFIO_NOIOMMU and the "enable_unsafe_noiommu_mode"
>option enabled.
>
>From 'commit 03a76b60f8ba2797 ("vfio: Include No-IOMMU mode")',
>"This should make it very clear that this mode is not safe.
>Additionally, CAP_SYS_RAWIO privileges are necessary to work
>with groups and containers using this mode.  Groups making
>use of this support are named /dev/vfio/noiommu-$GROUP and
>can only make use of the special VFIO_NOIOMMU_IOMMU for the
>container.  Use of this mode, specifically binding a device
>without a native IOMMU group to a VFIO bus driver will taint
>the kernel and should therefore not be considered supported."
>
>Signed-off-by: Peng Fan <van.freenix@gmail.com>
>Cc: Eric Auger <eric.auger@linaro.org>
>Cc: Baptiste Reynal <b.reynal@virtualopensystems.com>
>Cc: Alex Williamson <alex.williamson@redhat.com>
>---
>
>V3:
> The platform device can be programmed to do DMA without
> caring out mmap + VFIO_IOMMU_MAP_DMA which are not
> support by noiommu. So drop the last sentence of commit log
> in V2, which is misleading.
>
>V2:
> Rename subject to support No-IOMMU
> Add more commit log.
> I wrote a simple program following this
> https://github.com/virtualopensystems/vfio-host-test/blob/master/src_test/vfio_device_test.c
> ,no dma support. The device's register can be
> accessed in userspace using command './vfio_dev_test 30b60000.usdhc 0 1 platform'
>
> drivers/vfio/platform/vfio_platform_common.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
>diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
>index e65b142..993b2f9 100644
>--- a/drivers/vfio/platform/vfio_platform_common.c
>+++ b/drivers/vfio/platform/vfio_platform_common.c
>@@ -561,7 +561,7 @@ int vfio_platform_probe_common(struct vfio_platform_device *vdev,
> 
> 	vdev->device = dev;
> 
>-	group = iommu_group_get(dev);
>+	group = vfio_iommu_group_get(dev);
> 	if (!group) {
> 		pr_err("VFIO: No IOMMU group for device %s\n", vdev->name);
> 		return -EINVAL;
>@@ -569,7 +569,7 @@ int vfio_platform_probe_common(struct vfio_platform_device *vdev,
> 
> 	ret = vfio_add_group_dev(dev, &vfio_platform_ops, vdev);
> 	if (ret) {
>-		iommu_group_put(group);
>+		vfio_iommu_group_put(group, dev);
> 		return ret;
> 	}
> 
>@@ -589,7 +589,7 @@ struct vfio_platform_device *vfio_platform_remove_common(struct device *dev)
> 
> 	if (vdev) {
> 		vfio_platform_put_reset(vdev);
>-		iommu_group_put(dev->iommu_group);
>+		vfio_iommu_group_put(dev->iommu_group, dev);
> 	}
> 
> 	return vdev;
>-- 
>2.6.2
>

Re: [PATCH V3] vfio: platform: support No-IOMMU mode

[Auger Eric]

Hi Peng
Le 23/05/2016 à 11:47, Peng Fan a écrit :
> The vfio No-IOMMU mode was supported by this
> 'commit 03a76b60f8ba2797 ("vfio: Include No-IOMMU mode")',
> but it only support vfio-pci.
> 
> Using vfio_iommu_group_get/put, but not iommu_group_get/put,
> the platform devices can be exposed to userspace with
> CONFIG_VFIO_NOIOMMU and the "enable_unsafe_noiommu_mode"
> option enabled.
> 
> From 'commit 03a76b60f8ba2797 ("vfio: Include No-IOMMU mode")',
> "This should make it very clear that this mode is not safe.
> Additionally, CAP_SYS_RAWIO privileges are necessary to work
> with groups and containers using this mode.  Groups making
> use of this support are named /dev/vfio/noiommu-$GROUP and
> can only make use of the special VFIO_NOIOMMU_IOMMU for the
> container.  Use of this mode, specifically binding a device
> without a native IOMMU group to a VFIO bus driver will taint
> the kernel and should therefore not be considered supported."
> 
> Signed-off-by: Peng Fan <van.freenix@gmail.com>
> Cc: Eric Auger <eric.auger@linaro.org>
> Cc: Baptiste Reynal <b.reynal@virtualopensystems.com>
> Cc: Alex Williamson <alex.williamson@redhat.com>
Looks good to me.
Reviewed-by: Eric Auger <eric.auger@redhat.com>

as a reminder may conflict with HiDma ACPI reset series.

Best Regards

Eric


> ---
> 
> V3:
>  The platform device can be programmed to do DMA without
>  caring out mmap + VFIO_IOMMU_MAP_DMA which are not
>  support by noiommu. So drop the last sentence of commit log
>  in V2, which is misleading.
> 
> V2:
>  Rename subject to support No-IOMMU
>  Add more commit log.
>  I wrote a simple program following this
>  https://github.com/virtualopensystems/vfio-host-test/blob/master/src_test/vfio_device_test.c
>  ,no dma support. The device's register can be
>  accessed in userspace using command './vfio_dev_test 30b60000.usdhc 0 1 platform'
> 
>  drivers/vfio/platform/vfio_platform_common.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
> index e65b142..993b2f9 100644
> --- a/drivers/vfio/platform/vfio_platform_common.c
> +++ b/drivers/vfio/platform/vfio_platform_common.c
> @@ -561,7 +561,7 @@ int vfio_platform_probe_common(struct vfio_platform_device *vdev,
>  
>  	vdev->device = dev;
>  
> -	group = iommu_group_get(dev);
> +	group = vfio_iommu_group_get(dev);
>  	if (!group) {
>  		pr_err("VFIO: No IOMMU group for device %s\n", vdev->name);
>  		return -EINVAL;
> @@ -569,7 +569,7 @@ int vfio_platform_probe_common(struct vfio_platform_device *vdev,
>  
>  	ret = vfio_add_group_dev(dev, &vfio_platform_ops, vdev);
>  	if (ret) {
> -		iommu_group_put(group);
> +		vfio_iommu_group_put(group, dev);
>  		return ret;
>  	}
>  
> @@ -589,7 +589,7 @@ struct vfio_platform_device *vfio_platform_remove_common(struct device *dev)
>  
>  	if (vdev) {
>  		vfio_platform_put_reset(vdev);
> -		iommu_group_put(dev->iommu_group);
> +		vfio_iommu_group_put(dev->iommu_group, dev);
>  	}
>  
>  	return vdev;
> 

Re: [PATCH V3] vfio: platform: support No-IOMMU mode

[Alex Williamson]

On Sun, 12 Jun 2016 17:02:00 +0800
Peng Fan <van.freenix@gmail.com> wrote:

> Hi,
> 
> Kindly ping.. Any comments on V3?
> 
> Thanks,
> Peng.
> On Mon, May 23, 2016 at 05:47:30PM +0800, Peng Fan wrote:
> >The vfio No-IOMMU mode was supported by this
> >'commit 03a76b60f8ba2797 ("vfio: Include No-IOMMU mode")',
> >but it only support vfio-pci.
> >
> >Using vfio_iommu_group_get/put, but not iommu_group_get/put,
> >the platform devices can be exposed to userspace with
> >CONFIG_VFIO_NOIOMMU and the "enable_unsafe_noiommu_mode"
> >option enabled.
> >
> >From 'commit 03a76b60f8ba2797 ("vfio: Include No-IOMMU mode")',
> >"This should make it very clear that this mode is not safe.
> >Additionally, CAP_SYS_RAWIO privileges are necessary to work
> >with groups and containers using this mode.  Groups making
> >use of this support are named /dev/vfio/noiommu-$GROUP and
> >can only make use of the special VFIO_NOIOMMU_IOMMU for the
> >container.  Use of this mode, specifically binding a device
> >without a native IOMMU group to a VFIO bus driver will taint
> >the kernel and should therefore not be considered supported."
> >
> >Signed-off-by: Peng Fan <van.freenix@gmail.com>
> >Cc: Eric Auger <eric.auger@linaro.org>
> >Cc: Baptiste Reynal <b.reynal@virtualopensystems.com>
> >Cc: Alex Williamson <alex.williamson@redhat.com>
> >---

Applied with Eric's R-b to next branch for v4.8.  Thanks!

Alex

> >
> >V3:
> > The platform device can be programmed to do DMA without
> > caring out mmap + VFIO_IOMMU_MAP_DMA which are not
> > support by noiommu. So drop the last sentence of commit log
> > in V2, which is misleading.
> >
> >V2:
> > Rename subject to support No-IOMMU
> > Add more commit log.
> > I wrote a simple program following this
> > https://github.com/virtualopensystems/vfio-host-test/blob/master/src_test/vfio_device_test.c
> > ,no dma support. The device's register can be
> > accessed in userspace using command './vfio_dev_test 30b60000.usdhc 0 1 platform'
> >
> > drivers/vfio/platform/vfio_platform_common.c | 6 +++---
> > 1 file changed, 3 insertions(+), 3 deletions(-)
> >
> >diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
> >index e65b142..993b2f9 100644
> >--- a/drivers/vfio/platform/vfio_platform_common.c
> >+++ b/drivers/vfio/platform/vfio_platform_common.c
> >@@ -561,7 +561,7 @@ int vfio_platform_probe_common(struct vfio_platform_device *vdev,
> > 
> > 	vdev->device = dev;
> > 
> >-	group = iommu_group_get(dev);
> >+	group = vfio_iommu_group_get(dev);
> > 	if (!group) {
> > 		pr_err("VFIO: No IOMMU group for device %s\n", vdev->name);
> > 		return -EINVAL;
> >@@ -569,7 +569,7 @@ int vfio_platform_probe_common(struct vfio_platform_device *vdev,
> > 
> > 	ret = vfio_add_group_dev(dev, &vfio_platform_ops, vdev);
> > 	if (ret) {
> >-		iommu_group_put(group);
> >+		vfio_iommu_group_put(group, dev);
> > 		return ret;
> > 	}
> > 
> >@@ -589,7 +589,7 @@ struct vfio_platform_device *vfio_platform_remove_common(struct device *dev)
> > 
> > 	if (vdev) {
> > 		vfio_platform_put_reset(vdev);
> >-		iommu_group_put(dev->iommu_group);
> >+		vfio_iommu_group_put(dev->iommu_group, dev);
> > 	}
> > 
> > 	return vdev;
> >-- 
> >2.6.2
> >