[Intel-xe] [PATCH v2 5/6] drm/xe/uapi: add the userspace bits for small-bar
Gwan-gyeong Mun
gwan-gyeong.mun at intel.com
Mon Mar 27 04:37:55 UTC 2023
On 3/23/23 1:59 PM, Matthew Auld wrote:
> Mostly the same as i915. We add a new hint for userspace to force an
> object into the mappable part of vram.
>
> We also need to tell userspace how large the mappable part is. In Vulkan
> for example, there will be two vram heaps for small-bar systems. And
> here the size of each heap needs to be known. Likewise the used/avail
> tracking needs to account for the mappable part.
>
> We also limit the available tracking going forward, such that we limit
> to privileged users only, since these values are system wide and are
> technically considered an info leak.
>
> v2 (Maarten):
> - s/NEEDS_CPU_ACCESS/NEEDS_VISIBLE_VRAM/ in the uapi. We also no
> longer require smem as an extra placement. This is more flexible,
> and lets us use this for clear-color surfaces, since we need CPU access
> there but we don't want to attach smem, since that effectively disables
> CCS from kernel pov.
> - Reject clear-color CCS buffers where NEEDS_VISIBLE_VRAM is not set,
> instead of migrating it behind the scenes.
> v3 (José)
> - Split the changes that limit the accounting for perfmon_capable()
> into a separate patch.
> - Use XE_BO_CREATE_VRAM_MASK.
>
> Signed-off-by: Matthew Auld <matthew.auld at intel.com>
> Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> Cc: Thomas Hellström <thomas.hellstrom at linux.intel.com>
> Cc: Gwan-gyeong Mun <gwan-gyeong.mun at intel.com>
> Cc: Lucas De Marchi <lucas.demarchi at intel.com>
> Cc: José Roberto de Souza <jose.souza at intel.com>
> Cc: Filip Hazubski <filip.hazubski at intel.com>
> Cc: Carl Zhang <carl.zhang at intel.com>
> Cc: Effie Yu <effie.yu at intel.com>
> Reviewed-by: José Roberto de Souza <jose.souza at intel.com>
> ---
> drivers/gpu/drm/xe/display/xe_fb_pin.c | 13 +++++++++++++
> drivers/gpu/drm/xe/xe_bo.c | 13 +++++++++++--
> drivers/gpu/drm/xe/xe_query.c | 13 +++++++++----
> drivers/gpu/drm/xe/xe_ttm_vram_mgr.c | 18 ++++++++++++++++++
> drivers/gpu/drm/xe/xe_ttm_vram_mgr.h | 4 ++++
> include/uapi/drm/xe_drm.h | 20 +++++++++++++++++++-
> 6 files changed, 74 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/xe/display/xe_fb_pin.c b/drivers/gpu/drm/xe/display/xe_fb_pin.c
> index 65c0bc28a3d1..2a0edf9401da 100644
> --- a/drivers/gpu/drm/xe/display/xe_fb_pin.c
> +++ b/drivers/gpu/drm/xe/display/xe_fb_pin.c
> @@ -195,6 +195,19 @@ static struct i915_vma *__xe_pin_fb_vma(struct intel_framebuffer *fb,
> goto err;
> }
>
> + /*
> + * If we need to able to access the clear-color value stored in the
> + * buffer, then we require that such buffers are also CPU accessible.
> + * This is important on small-bar systems where only some subset of VRAM
> + * is CPU accessible.
> + */
> + if (IS_DGFX(to_xe_device(bo->ttm.base.dev)) &&
> + intel_fb_rc_ccs_cc_plane(&fb->base) >= 0 &&
> + !(bo->flags & XE_BO_NEEDS_CPU_ACCESS)) {
> + ret = -EINVAL;
> + goto err;
> + }
> +
> /*
> * Pin the framebuffer, we can't use xe_bo_(un)pin functions as the
> * assumptions are incorrect for framebuffers
> diff --git a/drivers/gpu/drm/xe/xe_bo.c b/drivers/gpu/drm/xe/xe_bo.c
> index de57ccc5b57c..25b1a56c2afa 100644
> --- a/drivers/gpu/drm/xe/xe_bo.c
> +++ b/drivers/gpu/drm/xe/xe_bo.c
> @@ -893,7 +893,6 @@ static vm_fault_t xe_gem_fault(struct vm_fault *vmf)
> ret = ttm_bo_vm_fault_reserved(vmf,
> vmf->vma->vm_page_prot,
> TTM_BO_VM_NUM_PREFAULT);
> -
> drm_dev_exit(idx);
> } else {
> ret = ttm_bo_vm_dummy_page(vmf, vmf->vma->vm_page_prot);
> @@ -1518,6 +1517,7 @@ int xe_gem_create_ioctl(struct drm_device *dev, void *data,
> if (XE_IOCTL_ERR(xe, args->flags &
> ~(XE_GEM_CREATE_FLAG_DEFER_BACKING |
> XE_GEM_CREATE_FLAG_SCANOUT |
> + XE_GEM_CREATE_FLAG_NEEDS_VISIBLE_VRAM |
> xe->info.mem_region_mask)))
> return -EINVAL;
>
> @@ -1555,6 +1555,14 @@ int xe_gem_create_ioctl(struct drm_device *dev, void *data,
> bo_flags |= XE_BO_SCANOUT_BIT;
>
> bo_flags |= args->flags << (ffs(XE_BO_CREATE_SYSTEM_BIT) - 1);
> +
> + if (args->flags & XE_GEM_CREATE_FLAG_NEEDS_VISIBLE_VRAM) {
> + if (XE_IOCTL_ERR(xe, !(bo_flags & XE_BO_CREATE_VRAM_MASK)))
Hi Matt,
if (XE_IOCTL_ERR(xe, args->flags &
~(XE_GEM_CREATE_FLAG_DEFER_BACKING |
XE_GEM_CREATE_FLAG_SCANOUT |
xe->info.mem_region_mask)))
by the above check, compares args->flags and xe->info.mem_region_mask to
see if the XE_BO_CREATE_VRAM_MASK bit is on in args->flags,
But why is it checking bo_flags and XE_BO_CREATE_VRAM_MASK here, which
stored bit-shifted values of args->flags and not original args->flags?
It looks good to me, except for the part I asked about.
Br,
G.G.
> + return -EINVAL;
> +
> + bo_flags |= XE_BO_NEEDS_CPU_ACCESS;
> + }
> +
> bo = xe_bo_create(xe, NULL, vm, args->size, ttm_bo_type_device,
> bo_flags);
> if (vm) {
> @@ -1818,7 +1826,8 @@ int xe_bo_dumb_create(struct drm_file *file_priv,
>
> bo = xe_bo_create(xe, NULL, NULL, args->size, ttm_bo_type_device,
> XE_BO_CREATE_VRAM_IF_DGFX(to_gt(xe)) |
> - XE_BO_CREATE_USER_BIT | XE_BO_SCANOUT_BIT);
> + XE_BO_CREATE_USER_BIT | XE_BO_SCANOUT_BIT |
> + XE_BO_NEEDS_CPU_ACCESS);
> if (IS_ERR(bo))
> return PTR_ERR(bo);
>
> diff --git a/drivers/gpu/drm/xe/xe_query.c b/drivers/gpu/drm/xe/xe_query.c
> index 9ff806cafcdd..e94cad946507 100644
> --- a/drivers/gpu/drm/xe/xe_query.c
> +++ b/drivers/gpu/drm/xe/xe_query.c
> @@ -16,6 +16,7 @@
> #include "xe_gt.h"
> #include "xe_guc_hwconfig.h"
> #include "xe_macros.h"
> +#include "xe_ttm_vram_mgr.h"
>
> static const enum xe_engine_class xe_to_user_engine_class[] = {
> [XE_ENGINE_CLASS_RENDER] = DRM_XE_ENGINE_CLASS_RENDER,
> @@ -149,13 +150,17 @@ static int query_memory_usage(struct xe_device *xe,
> man->size;
>
> if (perfmon_capable()) {
> - usage->regions[usage->num_regions].used =
> - ttm_resource_manager_usage(man);
> + xe_ttm_vram_get_used(man,
> + &usage->regions[usage->num_regions].used,
> + &usage->regions[usage->num_regions].cpu_visible_used);
> } else {
> - usage->regions[usage->num_regions].used =
> - man->size;
> + usage->regions[usage->num_regions].used = man->size;
> + usage->regions[usage->num_regions].cpu_visible_used =
> + xe_ttm_vram_get_cpu_visible_size(man);
> }
>
> + usage->regions[usage->num_regions].cpu_visible_size =
> + xe_ttm_vram_get_cpu_visible_size(man);
> usage->num_regions++;
> }
> }
> diff --git a/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c b/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
> index cf081e4aedf6..654c5ae6516b 100644
> --- a/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
> +++ b/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
> @@ -458,3 +458,21 @@ void xe_ttm_vram_mgr_free_sgt(struct device *dev, enum dma_data_direction dir,
> sg_free_table(sgt);
> kfree(sgt);
> }
> +
> +u64 xe_ttm_vram_get_cpu_visible_size(struct ttm_resource_manager *man)
> +{
> + struct xe_ttm_vram_mgr *mgr = to_xe_ttm_vram_mgr(man);
> +
> + return mgr->visible_size;
> +}
> +
> +void xe_ttm_vram_get_used(struct ttm_resource_manager *man,
> + u64 *used, u64 *used_visible)
> +{
> + struct xe_ttm_vram_mgr *mgr = to_xe_ttm_vram_mgr(man);
> +
> + mutex_lock(&mgr->lock);
> + *used = mgr->mm.size - mgr->mm.avail;
> + *used_visible = mgr->visible_size - mgr->visible_avail;
> + mutex_unlock(&mgr->lock);
> +}
> diff --git a/drivers/gpu/drm/xe/xe_ttm_vram_mgr.h b/drivers/gpu/drm/xe/xe_ttm_vram_mgr.h
> index 35e5367a79fb..27f43490fa11 100644
> --- a/drivers/gpu/drm/xe/xe_ttm_vram_mgr.h
> +++ b/drivers/gpu/drm/xe/xe_ttm_vram_mgr.h
> @@ -25,6 +25,10 @@ int xe_ttm_vram_mgr_alloc_sgt(struct xe_device *xe,
> void xe_ttm_vram_mgr_free_sgt(struct device *dev, enum dma_data_direction dir,
> struct sg_table *sgt);
>
> +u64 xe_ttm_vram_get_cpu_visible_size(struct ttm_resource_manager *man);
> +void xe_ttm_vram_get_used(struct ttm_resource_manager *man,
> + u64 *used, u64 *used_visible);
> +
> static inline struct xe_ttm_vram_mgr_resource *
> to_xe_ttm_vram_mgr_resource(struct ttm_resource *res)
> {
> diff --git a/include/uapi/drm/xe_drm.h b/include/uapi/drm/xe_drm.h
> index 661d7929210c..5a9807d96761 100644
> --- a/include/uapi/drm/xe_drm.h
> +++ b/include/uapi/drm/xe_drm.h
> @@ -169,7 +169,9 @@ struct drm_xe_query_mem_usage {
> __u32 max_page_size;
> __u64 total_size;
> __u64 used;
> - __u64 reserved[8];
> + __u64 cpu_visible_size;
> + __u64 cpu_visible_used;
> + __u64 reserved[6];
> } regions[];
> };
>
> @@ -270,6 +272,22 @@ struct drm_xe_gem_create {
> */
> #define XE_GEM_CREATE_FLAG_DEFER_BACKING (0x1 << 24)
> #define XE_GEM_CREATE_FLAG_SCANOUT (0x1 << 25)
> +/*
> + * When using VRAM as a possible placement, ensure that the corresponding VRAM
> + * allocation will always use the CPU accessible part of VRAM. This is important
> + * for small-bar systems (on full-bar systems this gets turned into a noop).
> + *
> + * Note: System memory can be used as an extra placement if the kernel should
> + * spill the allocation to system memory, if space can't be made available in
> + * the CPU accessible part of VRAM (giving the same behaviour as the i915
> + * interface, see I915_GEM_CREATE_EXT_FLAG_NEEDS_CPU_ACCESS).
> + *
> + * Note: For clear-color CCS surfaces the kernel needs to read the clear-color
> + * value stored in the buffer, and on discrete platforms we need to use VRAM for
> + * display surfaces, therefore the kernel requires setting this flag for such
> + * objects, otherwise an error is thrown.
> + */
> +#define XE_GEM_CREATE_FLAG_NEEDS_VISIBLE_VRAM (0x1 << 26)
> __u32 flags;
>
> /**
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