[PATCH v2 0/3] dma-buf: map-info support

[PATCH v2 0/3] dma-buf: map-info support

[Rob Clark]

From: Rob Clark <robdclark@chromium.org>

See 1/3 for motivation.

Rob Clark (3):
  dma-buf: Add ioctl to query mmap info
  drm/prime: Wire up mmap_info support
  drm/msm/prime: Add mmap_info support

 drivers/dma-buf/dma-buf.c           | 26 ++++++++++++++++++++++++++
 drivers/gpu/drm/drm_prime.c         | 12 ++++++++++++
 drivers/gpu/drm/msm/msm_drv.c       |  1 +
 drivers/gpu/drm/msm/msm_drv.h       |  1 +
 drivers/gpu/drm/msm/msm_gem_prime.c | 11 +++++++++++
 include/drm/drm_drv.h               |  7 +++++++
 include/linux/dma-buf.h             |  7 +++++++
 include/uapi/linux/dma-buf.h        | 28 ++++++++++++++++++++++++++++
 8 files changed, 93 insertions(+)

-- 
2.36.1

[PATCH v2 1/3] dma-buf: Add ioctl to query mmap info

[Rob Clark]

From: Rob Clark <robdclark@chromium.org>

This is a fairly narrowly focused interface, providing a way for a VMM
in userspace to tell the guest kernel what pgprot settings to use when
mapping a buffer to guest userspace.

For buffers that get mapped into guest userspace, virglrenderer returns
a dma-buf fd to the VMM (crosvm or qemu).  In addition to mapping the
pages into the guest VM, it needs to report to drm/virtio in the guest
the cache settings to use for guest userspace.  In particular, on some
architectures, creating aliased mappings with different cache attributes
is frowned upon, so it is important that the guest mappings have the
same cache attributes as any potential host mappings.

Signed-off-by: Rob Clark <robdclark@chromium.org>
---
v2. fix compiler warning

 drivers/dma-buf/dma-buf.c    | 26 ++++++++++++++++++++++++++
 include/linux/dma-buf.h      |  7 +++++++
 include/uapi/linux/dma-buf.h | 28 ++++++++++++++++++++++++++++
 3 files changed, 61 insertions(+)

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 32f55640890c..87c52f080274 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -326,6 +326,29 @@ static long dma_buf_set_name(struct dma_buf *dmabuf, const char __user *buf)
 	return 0;
 }
 
+static long dma_buf_info(struct dma_buf *dmabuf, void __user *uarg)
+{
+	struct dma_buf_info arg;
+
+	if (copy_from_user(&arg, uarg, sizeof(arg)))
+		return -EFAULT;
+
+	switch (arg.param) {
+	case DMA_BUF_INFO_VM_PROT:
+		if (!dmabuf->ops->mmap_info)
+			return -ENOSYS;
+		arg.value = dmabuf->ops->mmap_info(dmabuf);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	if (copy_to_user(uarg, &arg, sizeof(arg)))
+		return -EFAULT;
+
+	return 0;
+}
+
 static long dma_buf_ioctl(struct file *file,
 			  unsigned int cmd, unsigned long arg)
 {
@@ -369,6 +392,9 @@ static long dma_buf_ioctl(struct file *file,
 	case DMA_BUF_SET_NAME_B:
 		return dma_buf_set_name(dmabuf, (const char __user *)arg);
 
+	case DMA_BUF_IOCTL_INFO:
+		return dma_buf_info(dmabuf, (void __user *)arg);
+
 	default:
 		return -ENOTTY;
 	}
diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
index 71731796c8c3..6f4de64a5937 100644
--- a/include/linux/dma-buf.h
+++ b/include/linux/dma-buf.h
@@ -283,6 +283,13 @@ struct dma_buf_ops {
 	 */
 	int (*mmap)(struct dma_buf *, struct vm_area_struct *vma);
 
+	/**
+	 * @mmap_info:
+	 *
+	 * Return mmapping info for the buffer.  See DMA_BUF_INFO_VM_PROT.
+	 */
+	int (*mmap_info)(struct dma_buf *);
+
 	int (*vmap)(struct dma_buf *dmabuf, struct iosys_map *map);
 	void (*vunmap)(struct dma_buf *dmabuf, struct iosys_map *map);
 };
diff --git a/include/uapi/linux/dma-buf.h b/include/uapi/linux/dma-buf.h
index b1523cb8ab30..a41adac0f46a 100644
--- a/include/uapi/linux/dma-buf.h
+++ b/include/uapi/linux/dma-buf.h
@@ -85,6 +85,32 @@ struct dma_buf_sync {
 
 #define DMA_BUF_NAME_LEN	32
 
+
+/**
+ * struct dma_buf_info - Query info about the buffer.
+ */
+struct dma_buf_info {
+
+#define DMA_BUF_INFO_VM_PROT      1
+#  define DMA_BUF_VM_PROT_WC      0
+#  define DMA_BUF_VM_PROT_CACHED  1
+
+	/**
+	 * @param: Which param to query
+	 *
+	 * DMA_BUF_INFO_BM_PROT:
+	 *     Query the access permissions of userspace mmap's of this buffer.
+	 *     Returns one of DMA_BUF_VM_PROT_x
+	 */
+	__u32 param;
+	__u32 pad;
+
+	/**
+	 * @value: Return value of the query.
+	 */
+	__u64 value;
+};
+
 #define DMA_BUF_BASE		'b'
 #define DMA_BUF_IOCTL_SYNC	_IOW(DMA_BUF_BASE, 0, struct dma_buf_sync)
 
@@ -95,4 +121,6 @@ struct dma_buf_sync {
 #define DMA_BUF_SET_NAME_A	_IOW(DMA_BUF_BASE, 1, __u32)
 #define DMA_BUF_SET_NAME_B	_IOW(DMA_BUF_BASE, 1, __u64)
 
+#define DMA_BUF_IOCTL_INFO	_IOWR(DMA_BUF_BASE, 2, struct dma_buf_info)
+
 #endif
-- 
2.36.1

[PATCH v2 2/3] drm/prime: Wire up mmap_info support

[Rob Clark]

From: Rob Clark <robdclark@chromium.org>

Just plumbing the thing thru an extra layer.

Signed-off-by: Rob Clark <robdclark@chromium.org>
---
 drivers/gpu/drm/drm_prime.c | 12 ++++++++++++
 include/drm/drm_drv.h       |  7 +++++++
 2 files changed, 19 insertions(+)

diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
index e3f09f18110c..f58586e131c5 100644
--- a/drivers/gpu/drm/drm_prime.c
+++ b/drivers/gpu/drm/drm_prime.c
@@ -784,6 +784,17 @@ int drm_gem_dmabuf_mmap(struct dma_buf *dma_buf, struct vm_area_struct *vma)
 }
 EXPORT_SYMBOL(drm_gem_dmabuf_mmap);
 
+static int drm_gem_dmabuf_mmap_info(struct dma_buf *dma_buf)
+{
+	struct drm_gem_object *obj = dma_buf->priv;
+	struct drm_device *dev = obj->dev;
+
+	if (!dev->driver->gem_prime_mmap_info)
+		return -ENOSYS;
+
+	return dev->driver->gem_prime_mmap_info(obj);
+}
+
 static const struct dma_buf_ops drm_gem_prime_dmabuf_ops =  {
 	.cache_sgt_mapping = true,
 	.attach = drm_gem_map_attach,
@@ -792,6 +803,7 @@ static const struct dma_buf_ops drm_gem_prime_dmabuf_ops =  {
 	.unmap_dma_buf = drm_gem_unmap_dma_buf,
 	.release = drm_gem_dmabuf_release,
 	.mmap = drm_gem_dmabuf_mmap,
+	.mmap_info = drm_gem_dmabuf_mmap_info,
 	.vmap = drm_gem_dmabuf_vmap,
 	.vunmap = drm_gem_dmabuf_vunmap,
 };
diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
index f6159acb8856..797c0f8c2dd0 100644
--- a/include/drm/drm_drv.h
+++ b/include/drm/drm_drv.h
@@ -355,6 +355,13 @@ struct drm_driver {
 	 */
 	int (*gem_prime_mmap)(struct drm_gem_object *obj, struct vm_area_struct *vma);
 
+	/**
+	 * @gem_prim_mmap_info:
+	 *
+	 * Get info about mmap setup by gem_prime_mmap.  See dma_buf_ops:mmap_info.
+	 */
+	int (*gem_prime_mmap_info)(struct drm_gem_object *obj);
+
 	/**
 	 * @dumb_create:
 	 *
-- 
2.36.1

[PATCH v2 3/3] drm/msm/prime: Add mmap_info support

[Rob Clark]

From: Rob Clark <robdclark@chromium.org>

Signed-off-by: Rob Clark <robdclark@chromium.org>
---
 drivers/gpu/drm/msm/msm_drv.c       |  1 +
 drivers/gpu/drm/msm/msm_drv.h       |  1 +
 drivers/gpu/drm/msm/msm_gem_prime.c | 11 +++++++++++
 3 files changed, 13 insertions(+)

diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
index 1ca4a92ba96e..4979aa8187ec 100644
--- a/drivers/gpu/drm/msm/msm_drv.c
+++ b/drivers/gpu/drm/msm/msm_drv.c
@@ -1044,6 +1044,7 @@ static const struct drm_driver msm_driver = {
 	.prime_fd_to_handle = drm_gem_prime_fd_to_handle,
 	.gem_prime_import_sg_table = msm_gem_prime_import_sg_table,
 	.gem_prime_mmap     = msm_gem_prime_mmap,
+	.gem_prime_mmap_info= msm_gem_prime_mmap_info,
 #ifdef CONFIG_DEBUG_FS
 	.debugfs_init       = msm_debugfs_init,
 #endif
diff --git a/drivers/gpu/drm/msm/msm_drv.h b/drivers/gpu/drm/msm/msm_drv.h
index 7330d7b5de8e..b4ace34ec889 100644
--- a/drivers/gpu/drm/msm/msm_drv.h
+++ b/drivers/gpu/drm/msm/msm_drv.h
@@ -271,6 +271,7 @@ void msm_gem_shrinker_init(struct drm_device *dev);
 void msm_gem_shrinker_cleanup(struct drm_device *dev);
 
 int msm_gem_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma);
+int msm_gem_prime_mmap_info(struct drm_gem_object *obj);
 struct sg_table *msm_gem_prime_get_sg_table(struct drm_gem_object *obj);
 int msm_gem_prime_vmap(struct drm_gem_object *obj, struct iosys_map *map);
 void msm_gem_prime_vunmap(struct drm_gem_object *obj, struct iosys_map *map);
diff --git a/drivers/gpu/drm/msm/msm_gem_prime.c b/drivers/gpu/drm/msm/msm_gem_prime.c
index c1d91863df05..2bacab7a1921 100644
--- a/drivers/gpu/drm/msm/msm_gem_prime.c
+++ b/drivers/gpu/drm/msm/msm_gem_prime.c
@@ -5,6 +5,7 @@
  */
 
 #include <linux/dma-buf.h>
+#include <uapi/linux/dma-buf.h>
 
 #include <drm/drm_prime.h>
 
@@ -26,6 +27,16 @@ int msm_gem_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
 	return drm_gem_prime_mmap(obj, vma);
 }
 
+int msm_gem_prime_mmap_info(struct drm_gem_object *obj)
+{
+	struct msm_gem_object *msm_obj = to_msm_bo(obj);
+
+	if (msm_obj->flags & MSM_BO_WC)
+		return DMA_BUF_VM_PROT_WC;
+
+	return DMA_BUF_VM_PROT_CACHED;
+}
+
 struct sg_table *msm_gem_prime_get_sg_table(struct drm_gem_object *obj)
 {
 	struct msm_gem_object *msm_obj = to_msm_bo(obj);
-- 
2.36.1

Re: [Linaro-mm-sig] [PATCH v2 1/3] dma-buf: Add ioctl to query mmap info

[Daniel Vetter]

On Mon, Aug 01, 2022 at 10:04:55AM -0700, Rob Clark wrote:
> From: Rob Clark <robdclark@chromium.org>
> 
> This is a fairly narrowly focused interface, providing a way for a VMM
> in userspace to tell the guest kernel what pgprot settings to use when
> mapping a buffer to guest userspace.
> 
> For buffers that get mapped into guest userspace, virglrenderer returns
> a dma-buf fd to the VMM (crosvm or qemu).  In addition to mapping the
> pages into the guest VM, it needs to report to drm/virtio in the guest
> the cache settings to use for guest userspace.  In particular, on some
> architectures, creating aliased mappings with different cache attributes
> is frowned upon, so it is important that the guest mappings have the
> same cache attributes as any potential host mappings.
> 
> Signed-off-by: Rob Clark <robdclark@chromium.org>
> ---
> v2. fix compiler warning

I think I bikeshedded this on irc already, here for the record too.

- this wont work for buffers which do change the mapping when they move
  (ttm can do that). And cros does make noises about discrete gpus I've
  heard, this matters even for you :-)
- I'm pretty sure this will put is even more onto the nasty people list
  that dma-api folks maintain, especially with passing this all to
  userspace
- follow_pte() can figure this out internally in the kernel and kvm is
  already using this, and I think doing this all internally with mmu
  notifier and what not to make sure it all stays in sync is the right
  approach. So your kvm/whatever combo should be able to figure out wth
  it's supposed to be doing.

I think if you make this a virtio special case like we've done with the
magic uuid stuff, then that would make sense. Making it a full dma-buf
interface doesn't imo.

Cheers, Daniel

> 
>  drivers/dma-buf/dma-buf.c    | 26 ++++++++++++++++++++++++++
>  include/linux/dma-buf.h      |  7 +++++++
>  include/uapi/linux/dma-buf.h | 28 ++++++++++++++++++++++++++++
>  3 files changed, 61 insertions(+)
> 
> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
> index 32f55640890c..87c52f080274 100644
> --- a/drivers/dma-buf/dma-buf.c
> +++ b/drivers/dma-buf/dma-buf.c
> @@ -326,6 +326,29 @@ static long dma_buf_set_name(struct dma_buf *dmabuf, const char __user *buf)
>  	return 0;
>  }
>  
> +static long dma_buf_info(struct dma_buf *dmabuf, void __user *uarg)
> +{
> +	struct dma_buf_info arg;
> +
> +	if (copy_from_user(&arg, uarg, sizeof(arg)))
> +		return -EFAULT;
> +
> +	switch (arg.param) {
> +	case DMA_BUF_INFO_VM_PROT:
> +		if (!dmabuf->ops->mmap_info)
> +			return -ENOSYS;
> +		arg.value = dmabuf->ops->mmap_info(dmabuf);
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	if (copy_to_user(uarg, &arg, sizeof(arg)))
> +		return -EFAULT;
> +
> +	return 0;
> +}
> +
>  static long dma_buf_ioctl(struct file *file,
>  			  unsigned int cmd, unsigned long arg)
>  {
> @@ -369,6 +392,9 @@ static long dma_buf_ioctl(struct file *file,
>  	case DMA_BUF_SET_NAME_B:
>  		return dma_buf_set_name(dmabuf, (const char __user *)arg);
>  
> +	case DMA_BUF_IOCTL_INFO:
> +		return dma_buf_info(dmabuf, (void __user *)arg);
> +
>  	default:
>  		return -ENOTTY;
>  	}
> diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
> index 71731796c8c3..6f4de64a5937 100644
> --- a/include/linux/dma-buf.h
> +++ b/include/linux/dma-buf.h
> @@ -283,6 +283,13 @@ struct dma_buf_ops {
>  	 */
>  	int (*mmap)(struct dma_buf *, struct vm_area_struct *vma);
>  
> +	/**
> +	 * @mmap_info:
> +	 *
> +	 * Return mmapping info for the buffer.  See DMA_BUF_INFO_VM_PROT.
> +	 */
> +	int (*mmap_info)(struct dma_buf *);
> +
>  	int (*vmap)(struct dma_buf *dmabuf, struct iosys_map *map);
>  	void (*vunmap)(struct dma_buf *dmabuf, struct iosys_map *map);
>  };
> diff --git a/include/uapi/linux/dma-buf.h b/include/uapi/linux/dma-buf.h
> index b1523cb8ab30..a41adac0f46a 100644
> --- a/include/uapi/linux/dma-buf.h
> +++ b/include/uapi/linux/dma-buf.h
> @@ -85,6 +85,32 @@ struct dma_buf_sync {
>  
>  #define DMA_BUF_NAME_LEN	32
>  
> +
> +/**
> + * struct dma_buf_info - Query info about the buffer.
> + */
> +struct dma_buf_info {
> +
> +#define DMA_BUF_INFO_VM_PROT      1
> +#  define DMA_BUF_VM_PROT_WC      0
> +#  define DMA_BUF_VM_PROT_CACHED  1
> +
> +	/**
> +	 * @param: Which param to query
> +	 *
> +	 * DMA_BUF_INFO_BM_PROT:
> +	 *     Query the access permissions of userspace mmap's of this buffer.
> +	 *     Returns one of DMA_BUF_VM_PROT_x
> +	 */
> +	__u32 param;
> +	__u32 pad;
> +
> +	/**
> +	 * @value: Return value of the query.
> +	 */
> +	__u64 value;
> +};
> +
>  #define DMA_BUF_BASE		'b'
>  #define DMA_BUF_IOCTL_SYNC	_IOW(DMA_BUF_BASE, 0, struct dma_buf_sync)
>  
> @@ -95,4 +121,6 @@ struct dma_buf_sync {
>  #define DMA_BUF_SET_NAME_A	_IOW(DMA_BUF_BASE, 1, __u32)
>  #define DMA_BUF_SET_NAME_B	_IOW(DMA_BUF_BASE, 1, __u64)
>  
> +#define DMA_BUF_IOCTL_INFO	_IOWR(DMA_BUF_BASE, 2, struct dma_buf_info)
> +
>  #endif
> -- 
> 2.36.1
> 
> _______________________________________________
> Linaro-mm-sig mailing list -- linaro-mm-sig@lists.linaro.org
> To unsubscribe send an email to linaro-mm-sig-leave@lists.linaro.org

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

Re: [Linaro-mm-sig] [PATCH v2 1/3] dma-buf: Add ioctl to query mmap info

[Rob Clark]

On Tue, Sep 6, 2022 at 12:46 PM Daniel Vetter <daniel@ffwll.ch> wrote:
>
> On Mon, Aug 01, 2022 at 10:04:55AM -0700, Rob Clark wrote:
> > From: Rob Clark <robdclark@chromium.org>
> >
> > This is a fairly narrowly focused interface, providing a way for a VMM
> > in userspace to tell the guest kernel what pgprot settings to use when
> > mapping a buffer to guest userspace.
> >
> > For buffers that get mapped into guest userspace, virglrenderer returns
> > a dma-buf fd to the VMM (crosvm or qemu).  In addition to mapping the
> > pages into the guest VM, it needs to report to drm/virtio in the guest
> > the cache settings to use for guest userspace.  In particular, on some
> > architectures, creating aliased mappings with different cache attributes
> > is frowned upon, so it is important that the guest mappings have the
> > same cache attributes as any potential host mappings.
> >
> > Signed-off-by: Rob Clark <robdclark@chromium.org>
> > ---
> > v2. fix compiler warning
>
> I think I bikeshedded this on irc already, here for the record too.

You should look at v3 (which I confusingly titled as v2, sry):

https://patchwork.freedesktop.org/patch/497799/?series=106847&rev=3

> - this wont work for buffers which do change the mapping when they move
>   (ttm can do that). And cros does make noises about discrete gpus I've
>   heard, this matters even for you :-)

Correct, in v3 you could use DMA_BUF_MAP_INCOHERENT for this case (or
we could add additional enum values.. DMA_BUF_MAP_IDK or whatever)

re: dgpu, I guess those will be pass-thru so not so relevant for this issue

> - I'm pretty sure this will put is even more onto the nasty people list
>   that dma-api folks maintain, especially with passing this all to
>   userspace
> - follow_pte() can figure this out internally in the kernel and kvm is
>   already using this, and I think doing this all internally with mmu
>   notifier and what not to make sure it all stays in sync is the right
>   approach. So your kvm/whatever combo should be able to figure out wth
>   it's supposed to be doing.

This doesn't help, because the VMM is in userspace.. it is the VMM
which needs this information.

> I think if you make this a virtio special case like we've done with the
> magic uuid stuff, then that would make sense. Making it a full dma-buf
> interface doesn't imo.

IMHO we can consider this (at least in case of v3) as a virtio
special, at least in the sense that it is opt-in for the exporting
driver, and exporting drivers are free to not play along

BR,
-R

>
> Cheers, Daniel
>
> >
> >  drivers/dma-buf/dma-buf.c    | 26 ++++++++++++++++++++++++++
> >  include/linux/dma-buf.h      |  7 +++++++
> >  include/uapi/linux/dma-buf.h | 28 ++++++++++++++++++++++++++++
> >  3 files changed, 61 insertions(+)
> >
> > diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
> > index 32f55640890c..87c52f080274 100644
> > --- a/drivers/dma-buf/dma-buf.c
> > +++ b/drivers/dma-buf/dma-buf.c
> > @@ -326,6 +326,29 @@ static long dma_buf_set_name(struct dma_buf *dmabuf, const char __user *buf)
> >       return 0;
> >  }
> >
> > +static long dma_buf_info(struct dma_buf *dmabuf, void __user *uarg)
> > +{
> > +     struct dma_buf_info arg;
> > +
> > +     if (copy_from_user(&arg, uarg, sizeof(arg)))
> > +             return -EFAULT;
> > +
> > +     switch (arg.param) {
> > +     case DMA_BUF_INFO_VM_PROT:
> > +             if (!dmabuf->ops->mmap_info)
> > +                     return -ENOSYS;
> > +             arg.value = dmabuf->ops->mmap_info(dmabuf);
> > +             break;
> > +     default:
> > +             return -EINVAL;
> > +     }
> > +
> > +     if (copy_to_user(uarg, &arg, sizeof(arg)))
> > +             return -EFAULT;
> > +
> > +     return 0;
> > +}
> > +
> >  static long dma_buf_ioctl(struct file *file,
> >                         unsigned int cmd, unsigned long arg)
> >  {
> > @@ -369,6 +392,9 @@ static long dma_buf_ioctl(struct file *file,
> >       case DMA_BUF_SET_NAME_B:
> >               return dma_buf_set_name(dmabuf, (const char __user *)arg);
> >
> > +     case DMA_BUF_IOCTL_INFO:
> > +             return dma_buf_info(dmabuf, (void __user *)arg);
> > +
> >       default:
> >               return -ENOTTY;
> >       }
> > diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
> > index 71731796c8c3..6f4de64a5937 100644
> > --- a/include/linux/dma-buf.h
> > +++ b/include/linux/dma-buf.h
> > @@ -283,6 +283,13 @@ struct dma_buf_ops {
> >        */
> >       int (*mmap)(struct dma_buf *, struct vm_area_struct *vma);
> >
> > +     /**
> > +      * @mmap_info:
> > +      *
> > +      * Return mmapping info for the buffer.  See DMA_BUF_INFO_VM_PROT.
> > +      */
> > +     int (*mmap_info)(struct dma_buf *);
> > +
> >       int (*vmap)(struct dma_buf *dmabuf, struct iosys_map *map);
> >       void (*vunmap)(struct dma_buf *dmabuf, struct iosys_map *map);
> >  };
> > diff --git a/include/uapi/linux/dma-buf.h b/include/uapi/linux/dma-buf.h
> > index b1523cb8ab30..a41adac0f46a 100644
> > --- a/include/uapi/linux/dma-buf.h
> > +++ b/include/uapi/linux/dma-buf.h
> > @@ -85,6 +85,32 @@ struct dma_buf_sync {
> >
> >  #define DMA_BUF_NAME_LEN     32
> >
> > +
> > +/**
> > + * struct dma_buf_info - Query info about the buffer.
> > + */
> > +struct dma_buf_info {
> > +
> > +#define DMA_BUF_INFO_VM_PROT      1
> > +#  define DMA_BUF_VM_PROT_WC      0
> > +#  define DMA_BUF_VM_PROT_CACHED  1
> > +
> > +     /**
> > +      * @param: Which param to query
> > +      *
> > +      * DMA_BUF_INFO_BM_PROT:
> > +      *     Query the access permissions of userspace mmap's of this buffer.
> > +      *     Returns one of DMA_BUF_VM_PROT_x
> > +      */
> > +     __u32 param;
> > +     __u32 pad;
> > +
> > +     /**
> > +      * @value: Return value of the query.
> > +      */
> > +     __u64 value;
> > +};
> > +
> >  #define DMA_BUF_BASE         'b'
> >  #define DMA_BUF_IOCTL_SYNC   _IOW(DMA_BUF_BASE, 0, struct dma_buf_sync)
> >
> > @@ -95,4 +121,6 @@ struct dma_buf_sync {
> >  #define DMA_BUF_SET_NAME_A   _IOW(DMA_BUF_BASE, 1, __u32)
> >  #define DMA_BUF_SET_NAME_B   _IOW(DMA_BUF_BASE, 1, __u64)
> >
> > +#define DMA_BUF_IOCTL_INFO   _IOWR(DMA_BUF_BASE, 2, struct dma_buf_info)
> > +
> >  #endif
> > --
> > 2.36.1
> >
> > _______________________________________________
> > Linaro-mm-sig mailing list -- linaro-mm-sig@lists.linaro.org
> > To unsubscribe send an email to linaro-mm-sig-leave@lists.linaro.org
>
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch

[PATCH v2 0/3] dma-buf: map-info support

[Rob Clark]

From: Rob Clark <robdclark@chromium.org>

See 1/3 for motivation.

Rob Clark (3):
  dma-buf: Add ioctl to query mmap coherency/cache info
  drm/prime: Wire up mmap_info support
  drm/msm/prime: Add mmap_info support

 drivers/dma-buf/dma-buf.c     | 63 ++++++++++++++++++++++++++------
 drivers/gpu/drm/drm_prime.c   |  3 ++
 drivers/gpu/drm/msm/msm_gem.c | 12 +++++++
 include/drm/drm_gem.h         | 11 ++++++
 include/linux/dma-buf.h       | 11 ++++++
 include/uapi/linux/dma-buf.h  | 68 +++++++++++++++++++++++++++++++++++
 6 files changed, 158 insertions(+), 10 deletions(-)

-- 
2.36.1