Message-ID: <0439749a-ed43-4dc8-8025-f7aa1eec10b7@redhat.com>
Date: Tue, 2 Sep 2025 10:02:40 +0200
From: Jocelyn Falempe <jfalempe@...hat.com>
To: Ryosuke Yasuoka <ryasuoka@...hat.com>, zack.rusin@...adcom.com,
 maarten.lankhorst@...ux.intel.com, mripard@...nel.org, tzimmermann@...e.de,
 airlied@...il.com, simona@...ll.ch
Cc: bcm-kernel-feedback-list@...adcom.com, linux-kernel@...r.kernel.org,
 dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH drm-misc-next 1/1] drm/vmwgfx: add drm_panic support for
 stdu

On 01/09/2025 10:36, Ryosuke Yasuoka wrote:
> Add drm_panic module for vmwgfx stdu so that panic screen can be
> displayed on panic.

Thanks for this work.

If I understand correctly, this will draw the panic screen to the vfbo 
buffer, and then in the panic_flush() function, use 
vmw_panic_bo_cpu_blit() to copy that to the guest_memory_bo.

I think it should be easier to directly write the panic screen to the 
guest_memory_bo.
To write to the guest_memory_bo, you can do something similar as 
vmw_bo_cpu_blit_line(), but using kmap_local_page_try_from_panic() 
instead of kmap_atomic_prot().

You will probably need a custom set_pixel() function, like what I've 
done for i915
https://elixir.bootlin.com/linux/v6.17-rc4/source/drivers/gpu/drm/xe/display/intel_bo.c#L98

Best regards,

-- 

Jocelyn

> 
> Signed-off-by: Ryosuke Yasuoka <ryasuoka@...hat.com>
> ---
>   drivers/gpu/drm/vmwgfx/vmwgfx_blit.c   |  43 ++++++++
>   drivers/gpu/drm/vmwgfx/vmwgfx_cmdbuf.c |  11 ++
>   drivers/gpu/drm/vmwgfx/vmwgfx_drv.h    |   4 +
>   drivers/gpu/drm/vmwgfx/vmwgfx_kms.c    |  48 +++++++++
>   drivers/gpu/drm/vmwgfx/vmwgfx_kms.h    |   1 +
>   drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c   | 139 +++++++++++++++++++++++++
>   6 files changed, 246 insertions(+)
> 
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_blit.c b/drivers/gpu/drm/vmwgfx/vmwgfx_blit.c
> index fa5841fda659..d7ed04531249 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_blit.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_blit.c
> @@ -514,6 +514,49 @@ static int vmw_external_bo_copy(struct vmw_bo *dst, u32 dst_offset,
>   	return ret;
>   }
>   
> +/* For drm_panic */
> +void vmw_panic_bo_cpu_blit(struct vmw_bo *vmw_dst, u32 dst_stride,
> +			   struct vmw_bo *vmw_src, u32 src_stride,
> +			   u32 w, u32 h, struct vmw_diff_cpy *diff)
> +{
> +	struct ttm_buffer_object *src = &vmw_src->tbo;
> +	struct ttm_buffer_object *dst = &vmw_dst->tbo;
> +	u32 j;
> +	u32 initial_line = 0;
> +	u32 dst_offset = 0;
> +	u32 src_offset = 0;
> +	int ret = 0;
> +	struct vmw_bo_blit_line_data d = {
> +		.mapped_dst = 0,
> +		.mapped_src = 0,
> +		.dst_addr = NULL,
> +		.src_addr = NULL,
> +		.dst_pages = dst->ttm->pages,
> +		.src_pages = src->ttm->pages,
> +		.dst_num_pages = PFN_UP(dst->resource->size),
> +		.src_num_pages = PFN_UP(src->resource->size),
> +		.dst_prot = ttm_io_prot(dst, dst->resource, PAGE_KERNEL),
> +		.src_prot = ttm_io_prot(src, src->resource, PAGE_KERNEL),
> +		.diff = diff,
> +	};
> +
> +	for (j = 0; j < h; ++j) {
> +		diff->line = j + initial_line;
> +		diff->line_offset = dst_offset % dst_stride;
> +		ret = vmw_bo_cpu_blit_line(&d, dst_offset, src_offset, w);
> +		if (ret)
> +			goto out;
> +
> +		dst_offset += dst_stride;
> +		src_offset += src_stride;
> +	}
> +out:
> +	if (d.src_addr)
> +		kunmap_atomic(d.src_addr);
> +	if (d.dst_addr)
> +		kunmap_atomic(d.dst_addr);
> +}
> +
>   /**
>    * vmw_bo_cpu_blit - in-kernel cpu blit.
>    *
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_cmdbuf.c b/drivers/gpu/drm/vmwgfx/vmwgfx_cmdbuf.c
> index 94e8982f5616..e39cc2f214be 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_cmdbuf.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_cmdbuf.c
> @@ -983,6 +983,17 @@ void *vmw_cmdbuf_alloc(struct vmw_cmdbuf_man *man,
>   	return header->cmd;
>   }
>   
> +/* For drm_panic */
> +char *vmw_panic_cmdbuf_reserve_cur(struct vmw_cmdbuf_man *man, size_t size)
> +{
> +	/* Refer to cur without cur_mutex since this func is called in panic handler */
> +	struct vmw_cmdbuf_header *cur = man->cur;
> +
> +	cur->reserved = size;
> +
> +	return (char *) (man->cur->cmd + man->cur_pos);
> +}
> +
>   /**
>    * vmw_cmdbuf_reserve_cur - Reserve space for commands in the current
>    * command buffer.
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
> index eda5b6f8f4c4..c71ce975bf52 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
> @@ -1271,6 +1271,7 @@ extern int vmw_cmdbuf_idle(struct vmw_cmdbuf_man *man, bool interruptible,
>   extern void *vmw_cmdbuf_reserve(struct vmw_cmdbuf_man *man, size_t size,
>   				int ctx_id, bool interruptible,
>   				struct vmw_cmdbuf_header *header);
> +extern char *vmw_panic_cmdbuf_reserve_cur(struct vmw_cmdbuf_man *man, size_t size);
>   extern void vmw_cmdbuf_commit(struct vmw_cmdbuf_man *man, size_t size,
>   			      struct vmw_cmdbuf_header *header,
>   			      bool flush);
> @@ -1329,6 +1330,9 @@ int vmw_bo_cpu_blit(struct vmw_bo *dst,
>   		    u32 src_offset, u32 src_stride,
>   		    u32 w, u32 h,
>   		    struct vmw_diff_cpy *diff);
> +void vmw_panic_bo_cpu_blit(struct vmw_bo *dst, u32 dst_stride,
> +			   struct vmw_bo *src, u32 src_stride,
> +			   u32 w, u32 h, struct vmw_diff_cpy *diff);
>   
>   /* Host messaging -vmwgfx_msg.c: */
>   void vmw_disable_backdoor(void);
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
> index 54ea1b513950..160a4efbf342 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
> @@ -1717,6 +1717,54 @@ void vmw_kms_lost_device(struct drm_device *dev)
>   	drm_atomic_helper_shutdown(dev);
>   }
>   
> +/* For drm_panic */
> +int vmw_du_panic_helper_plane_update(struct vmw_du_update_plane *update)
> +{
> +	struct drm_plane_state *state = update->plane->state;
> +	struct vmw_framebuffer_bo *vfbbo =
> +		container_of(update->vfb, typeof(*vfbbo), base);
> +	struct drm_rect src = drm_plane_state_src(state);
> +	struct drm_rect clip = {
> +		.x1 = 0,
> +		.y1 = 0,
> +		.x2 = (src.x2 >> 16) + !!(src.x2 & 0xFFFF),
> +		.y2 = (src.y2 >> 16) + !!(src.y2 & 0xFFFF),
> +	};
> +	DECLARE_VAL_CONTEXT(val_ctx, NULL, 0);
> +	uint32_t reserved_size = 0;
> +	uint32_t submit_size = 0;
> +	char *cmd;
> +	int ret;
> +
> +	vmw_bo_placement_set(vfbbo->buffer,
> +			     VMW_BO_DOMAIN_SYS | VMW_BO_DOMAIN_MOB | VMW_BO_DOMAIN_GMR,
> +			     VMW_BO_DOMAIN_SYS | VMW_BO_DOMAIN_MOB | VMW_BO_DOMAIN_GMR);
> +
> +	ret = vmw_validation_add_bo(&val_ctx, vfbbo->buffer);
> +	if (ret)
> +		return ret;
> +
> +	ret = vmw_validation_prepare(&val_ctx, NULL, false);
> +	if (ret)
> +		return ret;
> +
> +	reserved_size = update->calc_fifo_size(update, 1);
> +	cmd = vmw_panic_cmdbuf_reserve_cur(update->dev_priv->cman, reserved_size);
> +	if (!cmd)
> +		return -ENOMEM;
> +
> +	vmw_du_translate_to_crtc(state, &clip);
> +
> +	update->clip(update, cmd, &clip, 0, 0);
> +	submit_size = update->post_clip(update, cmd, &clip);
> +
> +	vmw_cmd_commit(update->dev_priv, submit_size);
> +
> +	vmw_kms_helper_validation_finish(update->dev_priv, NULL, &val_ctx,
> +					 NULL, NULL);
> +	return ret;
> +}
> +
>   /**
>    * vmw_du_helper_plane_update - Helper to do plane update on a display unit.
>    * @update: The closure structure.
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.h b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.h
> index 445471fe9be6..e6299390ffea 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.h
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.h
> @@ -499,6 +499,7 @@ int vmw_kms_stdu_readback(struct vmw_private *dev_priv,
>   			  struct drm_crtc *crtc);
>   
>   int vmw_du_helper_plane_update(struct vmw_du_update_plane *update);
> +int vmw_du_panic_helper_plane_update(struct vmw_du_update_plane *update);
>   
>   /**
>    * vmw_du_translate_to_crtc - Translate a rect from framebuffer to crtc
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c b/drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c
> index 20aab725e53a..65b41338c620 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c
> @@ -36,6 +36,7 @@
>   #include <drm/drm_atomic_helper.h>
>   #include <drm/drm_damage_helper.h>
>   #include <drm/drm_fourcc.h>
> +#include <drm/drm_panic.h>
>   #include <drm/drm_vblank.h>
>   
>   #define vmw_crtc_to_stdu(x) \
> @@ -1164,6 +1165,66 @@ static uint32_t vmw_stdu_bo_clip_cpu(struct vmw_du_update_plane  *update,
>   	return 0;
>   }
>   
> +/* For drm_panic */
> +static uint32_t
> +vmw_stdu_panic_bo_populate_update_cpu(struct vmw_du_update_plane  *update, void *cmd,
> +				      struct drm_rect *bb)
> +{
> +	struct vmw_du_update_plane_buffer *bo_update;
> +	struct vmw_screen_target_display_unit *stdu;
> +	struct vmw_framebuffer_bo *vfbbo;
> +	struct vmw_diff_cpy diff = VMW_CPU_BLIT_DIFF_INITIALIZER(0);
> +	struct vmw_stdu_update_gb_image *cmd_img = cmd;
> +	struct vmw_stdu_update *cmd_update;
> +	struct vmw_bo *src_bo, *dst_bo;
> +	s32 src_pitch, dst_pitch;
> +	s32 width, height;
> +
> +	bo_update = container_of(update, typeof(*bo_update), base);
> +	stdu = container_of(update->du, typeof(*stdu), base);
> +	vfbbo = container_of(update->vfb, typeof(*vfbbo), base);
> +
> +	width = bb->x2;
> +	height = bb->y2;
> +
> +	diff.cpp = stdu->cpp;
> +
> +	dst_bo = stdu->display_srf->res.guest_memory_bo;
> +	dst_pitch = stdu->display_srf->metadata.base_size.width * stdu->cpp;
> +
> +	src_bo = vfbbo->buffer;
> +	src_pitch = update->vfb->base.pitches[0];
> +
> +	vmw_panic_bo_cpu_blit(dst_bo, dst_pitch, src_bo, src_pitch,
> +			      width * stdu->cpp, height, &diff);
> +
> +	if (drm_rect_visible(&diff.rect)) {
> +		SVGA3dBox *box = &cmd_img->body.box;
> +
> +		cmd_img->header.id = SVGA_3D_CMD_UPDATE_GB_IMAGE;
> +		cmd_img->header.size = sizeof(cmd_img->body);
> +		cmd_img->body.image.sid = stdu->display_srf->res.id;
> +		cmd_img->body.image.face = 0;
> +		cmd_img->body.image.mipmap = 0;
> +
> +		box->x = diff.rect.x1;
> +		box->y = diff.rect.y1;
> +		box->z = 0;
> +		box->w = drm_rect_width(&diff.rect);
> +		box->h = drm_rect_height(&diff.rect);
> +		box->d = 1;
> +
> +		cmd_update = (struct vmw_stdu_update *)&cmd_img[1];
> +		vmw_stdu_populate_update(cmd_update, stdu->base.unit,
> +					 diff.rect.x1, diff.rect.x2,
> +					 diff.rect.y1, diff.rect.y2);
> +
> +		return sizeof(*cmd_img) + sizeof(*cmd_update);
> +	}
> +
> +	return 0;
> +}
> +
>   static uint32_t
>   vmw_stdu_bo_populate_update_cpu(struct vmw_du_update_plane  *update, void *cmd,
>   				struct drm_rect *bb)
> @@ -1228,6 +1289,28 @@ vmw_stdu_bo_populate_update_cpu(struct vmw_du_update_plane  *update, void *cmd,
>   	return 0;
>   }
>   
> +/* For drm_panic */
> +static int vmw_stdu_panic_plane_update_bo(struct vmw_private *dev_priv,
> +					  struct drm_plane *plane,
> +					  struct vmw_framebuffer *vfb)
> +{
> +	struct vmw_du_update_plane_buffer bo_update;
> +
> +	memset(&bo_update, 0, sizeof(struct vmw_du_update_plane_buffer));
> +	bo_update.base.plane = plane;
> +	bo_update.base.old_state = plane->state;
> +	bo_update.base.dev_priv = dev_priv;
> +	bo_update.base.du = vmw_crtc_to_du(plane->state->crtc);
> +	bo_update.base.vfb = vfb;
> +
> +	bo_update.base.calc_fifo_size = vmw_stdu_bo_fifo_size_cpu;
> +	bo_update.base.pre_clip = vmw_stdu_bo_pre_clip_cpu;
> +	bo_update.base.clip = vmw_stdu_bo_clip_cpu;
> +	bo_update.base.post_clip = vmw_stdu_panic_bo_populate_update_cpu;
> +
> +	return vmw_du_panic_helper_plane_update(&bo_update.base);
> +}
> +
>   /**
>    * vmw_stdu_plane_update_bo - Update display unit for bo backed fb.
>    * @dev_priv: device private.
> @@ -1458,6 +1541,60 @@ vmw_stdu_primary_plane_atomic_update(struct drm_plane *plane,
>   		vmw_fence_obj_unreference(&fence);
>   }
>   
> +static int
> +vmw_stdu_primary_plane_get_scanout_buffer(struct drm_plane *plane,
> +					  struct drm_scanout_buffer *sb)
> +{
> +	struct vmw_framebuffer *vfb;
> +	struct vmw_framebuffer_bo *vfbbo;
> +	void *virtual;
> +
> +	if (!plane->state || !plane->state->fb || !plane->state->visible)
> +		return -ENODEV;
> +
> +	vfb = vmw_framebuffer_to_vfb(plane->state->fb);
> +
> +	if (!vfb->bo)
> +		return -ENODEV;
> +
> +	vfbbo = container_of(vfb, typeof(*vfbbo), base);
> +	virtual = vmw_bo_map_and_cache(vfbbo->buffer);
> +	if (!virtual)
> +		return -ENODEV;
> +	iosys_map_set_vaddr(&sb->map[0], virtual);
> +
> +	sb->format = plane->state->fb->format;
> +	sb->width = plane->state->fb->width;
> +	sb->height = plane->state->fb->height;
> +	sb->pitch[0] = plane->state->fb->pitches[0];
> +
> +	return 0;
> +}
> +
> +static void vmw_stdu_primary_plane_panic_flush(struct drm_plane *plane)
> +{
> +	struct drm_plane_state *state = plane->state;
> +	struct vmw_plane_state *vps = vmw_plane_state_to_vps(state);
> +	struct drm_crtc *crtc = state->crtc;
> +	struct vmw_private *dev_priv = vmw_priv(crtc->dev);
> +	struct vmw_framebuffer *vfb = vmw_framebuffer_to_vfb(state->fb);
> +	struct vmw_screen_target_display_unit *stdu = vmw_crtc_to_stdu(crtc);
> +	int ret;
> +
> +	stdu->display_srf = vmw_user_object_surface(&vps->uo);
> +	stdu->content_fb_type = vps->content_fb_type;
> +	stdu->cpp = vps->cpp;
> +
> +	ret = vmw_stdu_bind_st(dev_priv, stdu, &stdu->display_srf->res);
> +	if (ret)
> +		DRM_ERROR("Failed to bind surface to STDU.\n");
> +
> +	if (vfb->bo)
> +		ret = vmw_stdu_panic_plane_update_bo(dev_priv, plane, vfb);
> +	if (ret)
> +		DRM_ERROR("Failed to update STDU.\n");
> +}
> +
>   static void
>   vmw_stdu_crtc_atomic_flush(struct drm_crtc *crtc,
>   			   struct drm_atomic_state *state)
> @@ -1506,6 +1643,8 @@ drm_plane_helper_funcs vmw_stdu_primary_plane_helper_funcs = {
>   	.atomic_update = vmw_stdu_primary_plane_atomic_update,
>   	.prepare_fb = vmw_stdu_primary_plane_prepare_fb,
>   	.cleanup_fb = vmw_stdu_primary_plane_cleanup_fb,
> +	.get_scanout_buffer = vmw_stdu_primary_plane_get_scanout_buffer,
> +	.panic_flush = vmw_stdu_primary_plane_panic_flush,
>   };
>   
>   static const struct drm_crtc_helper_funcs vmw_stdu_crtc_helper_funcs = {

Powered by blists - more mailing lists