Re: [igt-dev] [PATCH i-g-t v3 2/6] lib/xe: add visible vram helpers

["Souza, Jose" <jose.souza@intel.com>]

On Fri, 2023-07-14 at 15:42 +0100, Matthew Auld wrote:
> Add helpers for object creation and querying the cpu_visible related bits.
> 
> v2: Make it backwards compat with older kernels
> 
> Signed-off-by: Matthew Auld <matthew.auld@intel.com>
> Cc: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
> Reviewed-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
> ---
>  lib/xe/xe_query.c | 86 ++++++++++++++++++++++++++++++++++++++++++++++-
>  lib/xe/xe_query.h |  6 ++++
>  2 files changed, 91 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/xe/xe_query.c b/lib/xe/xe_query.c
> index f535ad853..5412fbeb5 100644
> --- a/lib/xe/xe_query.c
> +++ b/lib/xe/xe_query.c
> @@ -140,6 +140,17 @@ static uint64_t gt_vram_size(const struct drm_xe_query_mem_usage *mem_usage,
>  	return 0;
>  }
>  
> +static uint64_t gt_visible_vram_size(const struct drm_xe_query_mem_usage *mem_usage,
> +				     const struct drm_xe_query_gts *gts, int gt)
> +{
> +	int region_idx = ffs(native_region_for_gt(gts, gt)) - 1;
> +
> +	if (XE_IS_CLASS_VRAM(&mem_usage->regions[region_idx]))
> +		return mem_usage->regions[region_idx].cpu_visible_size;
> +
> +	return 0;
> +}
> +
>  static bool __mem_has_vram(struct drm_xe_query_mem_usage *mem_usage)
>  {
>  	for (int i = 0; i < mem_usage->num_regions; i++)
> @@ -246,9 +257,14 @@ struct xe_device *xe_device_get(int fd)
>  	xe_dev->hw_engines = xe_query_engines_new(fd, &xe_dev->number_hw_engines);
>  	xe_dev->mem_usage = xe_query_mem_usage_new(fd);
>  	xe_dev->vram_size = calloc(xe_dev->number_gt, sizeof(*xe_dev->vram_size));
> -	for (int gt = 0; gt < xe_dev->number_gt; gt++)
> +	xe_dev->visible_vram_size = calloc(xe_dev->number_gt, sizeof(*xe_dev->visible_vram_size));
> +	for (int gt = 0; gt < xe_dev->number_gt; gt++) {
>  		xe_dev->vram_size[gt] = gt_vram_size(xe_dev->mem_usage,
>  						     xe_dev->gts, gt);
> +		xe_dev->visible_vram_size[gt] =
> +			gt_visible_vram_size(xe_dev->mem_usage,
> +					     xe_dev->gts, gt);
> +	}
>  	xe_dev->default_alignment = __mem_default_alignment(xe_dev->mem_usage);
>  	xe_dev->has_vram = __mem_has_vram(xe_dev->mem_usage);
>  
> @@ -383,6 +399,33 @@ uint64_t vram_memory(int fd, int gt)
>  	return xe_has_vram(fd) ? native_region_for_gt(xe_dev->gts, gt) : 0;
>  }
>  
> +static uint64_t __xe_visible_vram_size(int fd, int gt)
> +{
> +	struct xe_device *xe_dev;
> +
> +	xe_dev = find_in_cache(fd);
> +	igt_assert(xe_dev);
> +
> +	return xe_dev->visible_vram_size[gt];
> +}
> +
> +/**
> + * visible_vram_memory:
> + * @fd: xe device fd
> + * @gt: gt id
> + *
> + * Returns vram memory bitmask for xe device @fd and @gt id, with
> + * XE_GEM_CREATE_FLAG_NEEDS_VISIBLE_VRAM also set, to ensure that CPU access is
> + * possible.
> + */
> +uint64_t visible_vram_memory(int fd, int gt)
> +{
> +	if (__xe_visible_vram_size(fd, gt))
> +		return vram_memory(fd, gt) | XE_GEM_CREATE_FLAG_NEEDS_VISIBLE_VRAM;
> +	else
> +		return vram_memory(fd, gt); /* older kernel */

We don't need to maintain any compability with older Xe kernels for now...

> +}
> +
>  /**
>   * vram_if_possible:
>   * @fd: xe device fd
> @@ -396,6 +439,28 @@ uint64_t vram_if_possible(int fd, int gt)
>  	return vram_memory(fd, gt) ?: system_memory(fd);
>  }
>  
> +/**
> + * visible_vram_if_possible:
> + * @fd: xe device fd
> + * @gt: gt id
> + *
> + * Returns vram memory bitmask for xe device @fd and @gt id or system memory if
> + * there's no vram memory available for @gt. Also attaches the
> + * XE_GEM_CREATE_FLAG_NEEDS_VISIBLE_VRAM to ensure that CPU access is possible
> + * when using vram.
> + */
> +uint64_t visible_vram_if_possible(int fd, int gt)
> +{
> +	uint64_t regions = all_memory_regions(fd);
> +	uint64_t system_memory = regions & 0x1;
> +	uint64_t vram = regions & (0x2 << gt);
> +
> +	if (__xe_visible_vram_size(fd, gt))
> +		return vram ? vram | XE_GEM_CREATE_FLAG_NEEDS_VISIBLE_VRAM : system_memory;
> +	else
> +		return vram ? vram : system_memory; /* older kernel */
> +}

so this can be dropped and current callers should use visible_vram_memory().

> +
>  /**
>   * xe_hw_engines:
>   * @fd: xe device fd
> @@ -536,6 +601,24 @@ uint64_t xe_vram_size(int fd, int gt)
>  	return xe_dev->vram_size[gt];
>  }
>  
> +/**
> + * xe_visible_vram_size:
> + * @fd: xe device fd
> + * @gt: gt
> + *
> + * Returns size of visible vram of xe device @fd.
> + */
> +uint64_t xe_visible_vram_size(int fd, int gt)
> +{
> +	uint64_t visible_size;
> +
> +	visible_size = __xe_visible_vram_size(fd, gt);
> +	if (!visible_size) /* older kernel */
> +		visible_size = xe_vram_size(fd, gt);
> +
> +	return visible_size;
> +}
> +
>  /**
>   * xe_get_default_alignment:
>   * @fd: xe device fd
> @@ -552,6 +635,7 @@ xe_dev_FN(xe_get_default_alignment, default_alignment, uint32_t);
>   */
>  xe_dev_FN(xe_va_bits, va_bits, uint32_t);
>  
> +
>  /**
>   * xe_dev_id:
>   * @fd: xe device fd
> diff --git a/lib/xe/xe_query.h b/lib/xe/xe_query.h
> index 68ca5a680..1b74c58ab 100644
> --- a/lib/xe/xe_query.h
> +++ b/lib/xe/xe_query.h
> @@ -47,6 +47,9 @@ struct xe_device {
>  	/** @vram_size: array of vram sizes for all gts */
>  	uint64_t *vram_size;
>  
> +	/** @visible_vram_size: array of visible vram sizes for all gts */
> +	uint64_t *visible_vram_size;
> +
>  	/** @default_alignment: safe alignment regardless region location */
>  	uint32_t default_alignment;
>  
> @@ -80,7 +83,9 @@ unsigned int xe_number_gt(int fd);
>  uint64_t all_memory_regions(int fd);
>  uint64_t system_memory(int fd);
>  uint64_t vram_memory(int fd, int gt);
> +uint64_t visible_vram_memory(int fd, int gt);
>  uint64_t vram_if_possible(int fd, int gt);
> +uint64_t visible_vram_if_possible(int fd, int gt);
>  struct drm_xe_engine_class_instance *xe_hw_engines(int fd);
>  struct drm_xe_engine_class_instance *xe_hw_engine(int fd, int idx);
>  struct drm_xe_query_mem_region *xe_mem_region(int fd, uint64_t region);
> @@ -91,6 +96,7 @@ struct drm_xe_query_config *xe_config(int fd);
>  unsigned int xe_number_hw_engines(int fd);
>  bool xe_has_vram(int fd);
>  uint64_t xe_vram_size(int fd, int gt);
> +uint64_t xe_visible_vram_size(int fd, int gt);
>  uint32_t xe_get_default_alignment(int fd);
>  uint32_t xe_va_bits(int fd);
>  uint16_t xe_dev_id(int fd);