Re: [PATCH v2 35/37] drm/i915/query: Expose memory regions through the query uAPI

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 27/06/2019 21:56, Matthew Auld wrote:
> From: Abdiel Janulgue <abdiel.janulgue@linux.intel.com>
> 
> Returns the available memory region areas supported by the HW.
> 
> Signed-off-by: Abdiel Janulgue <abdiel.janulgue@linux.intel.com>
> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> ---
>   drivers/gpu/drm/i915/i915_query.c | 57 +++++++++++++++++++++++++++++++
>   include/uapi/drm/i915_drm.h       | 39 +++++++++++++++++++++
>   2 files changed, 96 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_query.c b/drivers/gpu/drm/i915/i915_query.c
> index 7b7016171057..21c4c2592d6c 100644
> --- a/drivers/gpu/drm/i915/i915_query.c
> +++ b/drivers/gpu/drm/i915/i915_query.c
> @@ -143,10 +143,67 @@ query_engine_info(struct drm_i915_private *i915,
>   	return len;
>   }
>   
> +static int query_memregion_info(struct drm_i915_private *dev_priv,
> +				struct drm_i915_query_item *query_item)
> +{
> +	struct drm_i915_query_memory_region_info __user *query_ptr =
> +		u64_to_user_ptr(query_item->data_ptr);
> +	struct drm_i915_memory_region_info __user *info_ptr =
> +		&query_ptr->regions[0];
> +	struct drm_i915_memory_region_info info = { };
> +	struct drm_i915_query_memory_region_info query;
> +	u32 total_length;
> +	int ret, i;
> +
> +	if (query_item->flags != 0)
> +		return -EINVAL;
> +
> +	total_length = sizeof(struct drm_i915_query_memory_region_info);
> +	for (i = 0; i < ARRAY_SIZE(dev_priv->regions); ++i) {
> +		struct intel_memory_region *region = dev_priv->regions[i];
> +
> +		if (!region)
> +			continue;
> +
> +		total_length += sizeof(struct drm_i915_memory_region_info);
> +	}
> +
> +	ret = copy_query_item(&query, sizeof(query), total_length,
> +			      query_item);
> +	if (ret != 0)
> +		return ret;
> +
> +	if (query.num_regions || query.rsvd[0] || query.rsvd[1] ||
> +	    query.rsvd[2])
> +		return -EINVAL;
> +
> +	for (i = 0; i < ARRAY_SIZE(dev_priv->regions); ++i) {
> +		struct intel_memory_region *region = dev_priv->regions[i];
> +
> +		if (!region)
> +			continue;
> +
> +		info.id = region->id;
> +		info.size = resource_size(&region->region);
> +
> +		if (__copy_to_user(info_ptr, &info, sizeof(info)))
> +			return -EFAULT;
> +
> +		query.num_regions++;
> +		info_ptr++;
> +	}
> +
> +	if (__copy_to_user(query_ptr, &query, sizeof(query)))
> +		return -EFAULT;
> +
> +	return total_length;
> +}
> +
>   static int (* const i915_query_funcs[])(struct drm_i915_private *dev_priv,
>   					struct drm_i915_query_item *query_item) = {
>   	query_topology_info,
>   	query_engine_info,
> +	query_memregion_info,
>   };
>   
>   int i915_query_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
> diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
> index 5cf976e7608a..9b77d8af9877 100644
> --- a/include/uapi/drm/i915_drm.h
> +++ b/include/uapi/drm/i915_drm.h
> @@ -2041,6 +2041,7 @@ struct drm_i915_query_item {
>   	__u64 query_id;
>   #define DRM_I915_QUERY_TOPOLOGY_INFO    1
>   #define DRM_I915_QUERY_ENGINE_INFO	2
> +#define DRM_I915_QUERY_MEMREGION_INFO   3
>   /* Must be kept compact -- no holes and well documented */
>   
>   	/*
> @@ -2180,6 +2181,44 @@ struct drm_i915_query_engine_info {
>   	struct drm_i915_engine_info engines[];
>   };
>   
> +struct drm_i915_memory_region_info {
> +
> +	/** Base type of a region
> +	 */
> +#define I915_SYSTEM_MEMORY         0
> +#define I915_DEVICE_MEMORY         1
> +
> +	/** The region id is encoded in a layout which makes it possible to
> +	 *  retrieve the following information:
> +	 *
> +	 *  Base type: log2(ID >> 16)
> +	 *  Instance:  log2(ID & 0xffff)
> +	 */
> +	__u32 id;

Should we consider, for simplicity and similarity with the engine 
interface, go for something like:

struct i915_memory_type_instance {
	__u16 type;
	__u16 instance;
};

struct drm_i915_memory_region_info {
	struct i915_memory_type_instance region;
	...
};

?

> +
> +	/** Reserved field. MBZ */
> +	__u32 rsvd0;
> +
> +	/** Unused for now. MBZ */
> +	__u64 flags;
> +
> +	__u64 size;
> +
> +	/** Reserved fields must be cleared to zero. */
> +	__u64 rsvd1[4];
> +};
> +
> +struct drm_i915_query_memory_region_info {
> +
> +	/** Number of struct drm_i915_memory_region_info structs */
> +	__u32 num_regions;
> +
> +	/** MBZ */
> +	__u32 rsvd[3];

It's not that important, just a note that given some recent discussion 
on the engine query front, I wished I had more rsvd there. So maybe bump 
this up just to be extra safe.

> +
> +	struct drm_i915_memory_region_info regions[];
> +};
> +
>   #if defined(__cplusplus)
>   }
>   #endif
> 

Regards,

Tvrtko
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