thr3ads.net - Linux Virtualization - [EXT] Re: [RFC PATCH v2] iommu/virtio: Use page size bitmap supported by endpoint [Apr 2020]

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Robin Murphy

2020-Apr-01 13:00 UTC

[RFC PATCH v2] iommu/virtio: Use page size bitmap supported by endpoint

On 2020-04-01 12:38 pm, Bharat Bhushan wrote:> Different endpoint can support different page size, probe
> endpoint if it supports specific page size otherwise use
> global page sizes.
> 
> Signed-off-by: Bharat Bhushan <bbhushan2 at marvell.com>
> ---
>   drivers/iommu/virtio-iommu.c      | 33 +++++++++++++++++++++++++++----
>   include/uapi/linux/virtio_iommu.h |  7 +++++++
>   2 files changed, 36 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/iommu/virtio-iommu.c b/drivers/iommu/virtio-iommu.c
> index cce329d71fba..c794cb5b7b3e 100644
> --- a/drivers/iommu/virtio-iommu.c
> +++ b/drivers/iommu/virtio-iommu.c
> @@ -78,6 +78,7 @@ struct viommu_endpoint {
>   	struct viommu_dev		*viommu;
>   	struct viommu_domain		*vdomain;
>   	struct list_head		resv_regions;
> +	u64				pgsize_bitmap;
>   };
>   
>   struct viommu_request {
> @@ -415,6 +416,20 @@ static int viommu_replay_mappings(struct viommu_domain
*vdomain)
>   	return ret;
>   }
>   
> +static int viommu_set_pgsize_bitmap(struct viommu_endpoint *vdev,
> +				    struct virtio_iommu_probe_pgsize_mask *mask,
> +				    size_t len)
> +
> +{
> +	u64 pgsize_bitmap = le64_to_cpu(mask->pgsize_bitmap);
> +
> +	if (len < sizeof(*mask))
> +		return -EINVAL;
> +
> +	vdev->pgsize_bitmap = pgsize_bitmap;
> +	return 0;
> +}
> +
>   static int viommu_add_resv_mem(struct viommu_endpoint *vdev,
>   			       struct virtio_iommu_probe_resv_mem *mem,
>   			       size_t len)
> @@ -494,11 +509,13 @@ static int viommu_probe_endpoint(struct viommu_dev
*viommu, struct device *dev)
>   	while (type != VIRTIO_IOMMU_PROBE_T_NONE &&
>   	       cur < viommu->probe_size) {
>   		len = le16_to_cpu(prop->length) + sizeof(*prop);
> -
>   		switch (type) {
>   		case VIRTIO_IOMMU_PROBE_T_RESV_MEM:
>   			ret = viommu_add_resv_mem(vdev, (void *)prop, len);
>   			break;
> +		case VIRTIO_IOMMU_PROBE_T_PAGE_SIZE_MASK:
> +			ret = viommu_set_pgsize_bitmap(vdev, (void *)prop, len);
> +			break;
>   		default:
>   			dev_err(dev, "unknown viommu prop 0x%x\n", type);
>   		}
> @@ -607,16 +624,23 @@ static struct iommu_domain
*viommu_domain_alloc(unsigned type)
>   	return &vdomain->domain;
>   }
>   
> -static int viommu_domain_finalise(struct viommu_dev *viommu,
> +static int viommu_domain_finalise(struct viommu_endpoint *vdev,
>   				  struct iommu_domain *domain)
>   {
>   	int ret;
>   	struct viommu_domain *vdomain = to_viommu_domain(domain);
> +	struct viommu_dev *viommu = vdev->viommu;
>   
>   	vdomain->viommu		= viommu;
>   	vdomain->map_flags	= viommu->map_flags;
>   
> -	domain->pgsize_bitmap	= viommu->pgsize_bitmap;
> +	/* Devices in same domain must support same size pages */
AFAICS what the code appears to do is enforce that the first endpoint 
attached to any domain has the same pgsize_bitmap as the most recently 
probed viommu_dev instance, then ignore any subsequent endpoints 
attached to the same domain. Thus I'm not sure that comment is accurate.

Robin.
> +	if ((domain->pgsize_bitmap != viommu->pgsize_bitmap) &&
> +	    (domain->pgsize_bitmap != vdev->pgsize_bitmap))
> +		return -EINVAL;
> +
> +	domain->pgsize_bitmap = vdev->pgsize_bitmap;
> +
>   	domain->geometry	= viommu->geometry;
>   
>   	ret = ida_alloc_range(&viommu->domain_ids,
viommu->first_domain,
> @@ -657,7 +681,7 @@ static int viommu_attach_dev(struct iommu_domain
*domain, struct device *dev)
>   		 * Properly initialize the domain now that we know which viommu
>   		 * owns it.
>   		 */
> -		ret = viommu_domain_finalise(vdev->viommu, domain);
> +		ret = viommu_domain_finalise(vdev, domain);
>   	} else if (vdomain->viommu != vdev->viommu) {
>   		dev_err(dev, "cannot attach to foreign vIOMMU\n");
>   		ret = -EXDEV;
> @@ -875,6 +899,7 @@ static int viommu_add_device(struct device *dev)
>   
>   	vdev->dev = dev;
>   	vdev->viommu = viommu;
> +	vdev->pgsize_bitmap = viommu->pgsize_bitmap;
>   	INIT_LIST_HEAD(&vdev->resv_regions);
>   	fwspec->iommu_priv = vdev;
>   
> diff --git a/include/uapi/linux/virtio_iommu.h
b/include/uapi/linux/virtio_iommu.h
> index 237e36a280cb..dc9d3f40bcd8 100644
> --- a/include/uapi/linux/virtio_iommu.h
> +++ b/include/uapi/linux/virtio_iommu.h
> @@ -111,6 +111,7 @@ struct virtio_iommu_req_unmap {
>   
>   #define VIRTIO_IOMMU_PROBE_T_NONE		0
>   #define VIRTIO_IOMMU_PROBE_T_RESV_MEM		1
> +#define VIRTIO_IOMMU_PROBE_T_PAGE_SIZE_MASK	2
>   
>   #define VIRTIO_IOMMU_PROBE_T_MASK		0xfff
>   
> @@ -119,6 +120,12 @@ struct virtio_iommu_probe_property {
>   	__le16					length;
>   };
>   
> +struct virtio_iommu_probe_pgsize_mask {
> +	struct virtio_iommu_probe_property	head;
> +	__u8					reserved[4];
> +	__u64					pgsize_bitmap;
> +};
> +
>   #define VIRTIO_IOMMU_RESV_MEM_T_RESERVED	0
>   #define VIRTIO_IOMMU_RESV_MEM_T_MSI		1
>   
>

Jean-Philippe Brucker

2020-Apr-01 15:49 UTC

head link

[RFC PATCH v2] iommu/virtio: Use page size bitmap supported by endpoint

On Wed, Apr 01, 2020 at 02:00:13PM +0100, Robin Murphy
wrote:> On 2020-04-01 12:38 pm, Bharat Bhushan wrote:
> > Different endpoint can support different page size, probe
> > endpoint if it supports specific page size otherwise use
> > global page sizes.
> > 
> > Signed-off-by: Bharat Bhushan <bbhushan2 at marvell.com>
> > ---
> >   drivers/iommu/virtio-iommu.c      | 33
+++++++++++++++++++++++++++----
> >   include/uapi/linux/virtio_iommu.h |  7 +++++++
> >   2 files changed, 36 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/iommu/virtio-iommu.c
b/drivers/iommu/virtio-iommu.c
> > index cce329d71fba..c794cb5b7b3e 100644
> > --- a/drivers/iommu/virtio-iommu.c
> > +++ b/drivers/iommu/virtio-iommu.c
> > @@ -78,6 +78,7 @@ struct viommu_endpoint {
> >   	struct viommu_dev		*viommu;
> >   	struct viommu_domain		*vdomain;
> >   	struct list_head		resv_regions;
> > +	u64				pgsize_bitmap;
> >   };
> >   struct viommu_request {
> > @@ -415,6 +416,20 @@ static int viommu_replay_mappings(struct
viommu_domain *vdomain)
> >   	return ret;
> >   }
> > +static int viommu_set_pgsize_bitmap(struct viommu_endpoint *vdev,
> > +				    struct virtio_iommu_probe_pgsize_mask *mask,
> > +				    size_t len)
> > +
> > +{
> > +	u64 pgsize_bitmap = le64_to_cpu(mask->pgsize_bitmap);
> > +
> > +	if (len < sizeof(*mask))
> > +		return -EINVAL;
> > +
> > +	vdev->pgsize_bitmap = pgsize_bitmap;
> > +	return 0;
> > +}
> > +
> >   static int viommu_add_resv_mem(struct viommu_endpoint *vdev,
> >   			       struct virtio_iommu_probe_resv_mem *mem,
> >   			       size_t len)
> > @@ -494,11 +509,13 @@ static int viommu_probe_endpoint(struct
viommu_dev *viommu, struct device *dev)
> >   	while (type != VIRTIO_IOMMU_PROBE_T_NONE &&
> >   	       cur < viommu->probe_size) {
> >   		len = le16_to_cpu(prop->length) + sizeof(*prop);
> > -
Whitespace change
> >   		switch (type) {
> >   		case VIRTIO_IOMMU_PROBE_T_RESV_MEM:
> >   			ret = viommu_add_resv_mem(vdev, (void *)prop, len);
> >   			break;
> > +		case VIRTIO_IOMMU_PROBE_T_PAGE_SIZE_MASK:
> > +			ret = viommu_set_pgsize_bitmap(vdev, (void *)prop, len);
> > +			break;
> >   		default:
> >   			dev_err(dev, "unknown viommu prop 0x%x\n", type);
> >   		}
> > @@ -607,16 +624,23 @@ static struct iommu_domain
*viommu_domain_alloc(unsigned type)
> >   	return &vdomain->domain;
> >   }
> > -static int viommu_domain_finalise(struct viommu_dev *viommu,
> > +static int viommu_domain_finalise(struct viommu_endpoint *vdev,
> >   				  struct iommu_domain *domain)
> >   {
> >   	int ret;
> >   	struct viommu_domain *vdomain = to_viommu_domain(domain);
> > +	struct viommu_dev *viommu = vdev->viommu;
> >   	vdomain->viommu		= viommu;
> >   	vdomain->map_flags	= viommu->map_flags;
> > -	domain->pgsize_bitmap	= viommu->pgsize_bitmap;
> > +	/* Devices in same domain must support same size pages */
> 
> AFAICS what the code appears to do is enforce that the first endpoint
> attached to any domain has the same pgsize_bitmap as the most recently
> probed viommu_dev instance, then ignore any subsequent endpoints attached
to
> the same domain. Thus I'm not sure that comment is accurate.
> 
Yes viommu_domain_finalise() is only called once. What I had in mind is
something like:

---- 8< ----
diff --git a/drivers/iommu/virtio-iommu.c b/drivers/iommu/virtio-iommu.c
index 750f69c49b95..8303b7b513ff 100644
--- a/drivers/iommu/virtio-iommu.c
+++ b/drivers/iommu/virtio-iommu.c
@@ -639,6 +639,29 @@ static int viommu_domain_finalise(struct viommu_endpoint
*vdev,
 	return 0;
 }
 
+/*
+ * Check whether the endpoint's capabilities are compatible with other
endpoints
+ * in the domain. Report any inconsistency.
+ */
+static bool viommu_endpoint_is_compatible(struct viommu_endpoint *vdev,
+					  struct viommu_domain *vdomain)
+{
+	struct device *dev = vdev->dev;
+
+	if (vdomain->viommu != vdev->viommu) {
+		dev_err(dev, "cannot attach to foreign vIOMMU\n");
+		return false;
+	}
+
+	if (vdomain->domain.pgsize_bitmap != vdev->pgsize_bitmap) {
+		dev_err(dev, "incompatible domain bitmap 0x%lx != 0x%lx\n",
+			vdomain->domain.pgsize_bitmap, vdev->pgsize_bitmap);
+		return false;
+	}
+
+	return true;
+}
+
 static void viommu_domain_free(struct iommu_domain *domain)
 {
 	struct viommu_domain *vdomain = to_viommu_domain(domain);
@@ -670,9 +693,8 @@ static int viommu_attach_dev(struct iommu_domain *domain,
struct device *dev)
 		 * owns it.
 		 */
 		ret = viommu_domain_finalise(vdev, domain);
-	} else if (vdomain->viommu != vdev->viommu) {
-		dev_err(dev, "cannot attach to foreign vIOMMU\n");
-		ret = -EXDEV;
+	} else if (!viommu_endpoint_is_compatible(vdev, vdomain)) {
+		ret = -EINVAL;
 	}
 	mutex_unlock(&vdomain->mutex);
---- >8 ----
> 
> > +	if ((domain->pgsize_bitmap != viommu->pgsize_bitmap)
&&
> > +	    (domain->pgsize_bitmap != vdev->pgsize_bitmap))
> > +		return -EINVAL;
> > +
> > +	domain->pgsize_bitmap = vdev->pgsize_bitmap;
> > +
> >   	domain->geometry	= viommu->geometry;
> >   	ret = ida_alloc_range(&viommu->domain_ids,
viommu->first_domain,
> > @@ -657,7 +681,7 @@ static int viommu_attach_dev(struct iommu_domain
*domain, struct device *dev)
> >   		 * Properly initialize the domain now that we know which viommu
> >   		 * owns it.
> >   		 */
> > -		ret = viommu_domain_finalise(vdev->viommu, domain);
> > +		ret = viommu_domain_finalise(vdev, domain);
> >   	} else if (vdomain->viommu != vdev->viommu) {
> >   		dev_err(dev, "cannot attach to foreign vIOMMU\n");
> >   		ret = -EXDEV;
> > @@ -875,6 +899,7 @@ static int viommu_add_device(struct device *dev)
> >   	vdev->dev = dev;
> >   	vdev->viommu = viommu;
> > +	vdev->pgsize_bitmap = viommu->pgsize_bitmap;
> >   	INIT_LIST_HEAD(&vdev->resv_regions);
> >   	fwspec->iommu_priv = vdev;
> > diff --git a/include/uapi/linux/virtio_iommu.h
b/include/uapi/linux/virtio_iommu.h
> > index 237e36a280cb..dc9d3f40bcd8 100644
> > --- a/include/uapi/linux/virtio_iommu.h
> > +++ b/include/uapi/linux/virtio_iommu.h
> > @@ -111,6 +111,7 @@ struct virtio_iommu_req_unmap {
> >   #define VIRTIO_IOMMU_PROBE_T_NONE		0
> >   #define VIRTIO_IOMMU_PROBE_T_RESV_MEM		1
> > +#define VIRTIO_IOMMU_PROBE_T_PAGE_SIZE_MASK	2
> >   #define VIRTIO_IOMMU_PROBE_T_MASK		0xfff
> > @@ -119,6 +120,12 @@ struct virtio_iommu_probe_property {
> >   	__le16					length;
> >   };
> > +struct virtio_iommu_probe_pgsize_mask {
> > +	struct virtio_iommu_probe_property	head;
> > +	__u8					reserved[4];
> > +	__u64					pgsize_bitmap;
Should be __le64

Thanks,
Jean
> > +};
> > +
> >   #define VIRTIO_IOMMU_RESV_MEM_T_RESERVED	0
> >   #define VIRTIO_IOMMU_RESV_MEM_T_MSI		1
> >

Jean-Philippe Brucker

2020-Apr-02 09:24 UTC

head link

[EXT] Re: [RFC PATCH v2] iommu/virtio: Use page size bitmap supported by endpoint

On Thu, Apr 02, 2020 at 03:53:40AM +0000, Bharat Bhushan
wrote:> > > > +struct virtio_iommu_probe_pgsize_mask {
> > > > +	struct virtio_iommu_probe_property	head;
> > > > +	__u8					reserved[4];
> > > > +	__u64					pgsize_bitmap;
> > 
> > Should be __le64
> 
> Based on" iommu/virtio: Fix sparse warning" patch
https://www.spinics.net/lists/linux-virtualization/msg41944.html changed to
__u64 (not __le64)
Yes that one was only for the virtio config struct, to play nice with
other devices. We should still use __le for the other structures,
including probe properties.

Thanks,
Jean
> 
> Will keep __le64.
> 
> Thanks
> -Bharat
> 
> > 
> > Thanks,
> > Jean
> > 
> > > > +};
> > > > +
> > > >   #define VIRTIO_IOMMU_RESV_MEM_T_RESERVED	0
> > > >   #define VIRTIO_IOMMU_RESV_MEM_T_MSI		1
> > > >

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