[PATCH RFC drm-misc-next v2 0/1] Add support for drm_panic

[PATCH RFC drm-misc-next v2 0/1] Add support for drm_panic

[Ryosuke Yasuoka]

This patch adds drm_panic support for hyperv-drm driver. This function
works but it's still needed to brush up. Let me hear your opinions.

Once kernel panic occurs we expect to see a panic screen. However, to
see the screen, I need to close/re-open the graphic console client
window. As the panic screen shows correctly in the small preview
window in Hyper-V manager and debugfs API for drm_panic works correctly,
I think kernel needs to send signal to Hyper-V host that the console
client refreshes, but I have no idea what kind of signal is needed.

This patch is tested on Hyper-V 2022.

v2:
- Re-write codes with regular atomic helper. The driver was implemented
  with simple KMS. So replace it with regular atomic helper in [1],
  implement this feature on it.

[1] https://lore.kernel.org/all/20250427101825.812766-1-ryasuoka@redhat.com/

v1:
https://lore.kernel.org/lkml/20250402084351.1545536-1-ryasuoka@redhat.com/

Ryosuke Yasuoka (1):
  drm/hyperv: Add support for drm_panic

 drivers/gpu/drm/hyperv/hyperv_drm_modeset.c | 36 +++++++++++++++++++++
 1 file changed, 36 insertions(+)


base-commit: c06cb85ad1412c6ff34792b028b2f89495761398
-- 
2.49.0

[PATCH RFC drm-misc-next v2 1/1] drm/hyperv: Add support for drm_panic

[Ryosuke Yasuoka]

Add drm_panic module for hyperv drm so that panic screen can be
displayed on panic.

Signed-off-by: Ryosuke Yasuoka <ryasuoka@redhat.com>
---
 drivers/gpu/drm/hyperv/hyperv_drm_modeset.c | 36 +++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/drivers/gpu/drm/hyperv/hyperv_drm_modeset.c b/drivers/gpu/drm/hyperv/hyperv_drm_modeset.c
index f7d2e973f79e..945b9482bcb3 100644
--- a/drivers/gpu/drm/hyperv/hyperv_drm_modeset.c
+++ b/drivers/gpu/drm/hyperv/hyperv_drm_modeset.c
@@ -17,6 +17,7 @@
 #include <drm/drm_gem_framebuffer_helper.h>
 #include <drm/drm_gem_shmem_helper.h>
 #include <drm/drm_probe_helper.h>
+#include <drm/drm_panic.h>
 #include <drm/drm_plane.h>
 
 #include "hyperv_drm.h"
@@ -181,10 +182,45 @@ static void hyperv_plane_atomic_update(struct drm_plane *plane,
 	}
 }
 
+static int hyperv_plane_get_scanout_buffer(struct drm_plane *plane,
+					   struct drm_scanout_buffer *sb)
+{
+	struct hyperv_drm_device *hv = to_hv(plane->dev);
+	struct iosys_map map = IOSYS_MAP_INIT_VADDR_IOMEM(hv->vram);
+
+	if (plane->state && plane->state->fb) {
+		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];
+		sb->map[0] = map;
+		return 0;
+	}
+	return -ENODEV;
+}
+
+static void hyperv_plane_panic_flush(struct drm_plane *plane)
+{
+	struct hyperv_drm_device *hv = to_hv(plane->dev);
+	struct drm_rect rect;
+
+	if (!plane->state || !plane->state->fb)
+		return;
+
+	rect.x1 = 0;
+	rect.y1 = 0;
+	rect.x2 = plane->state->fb->width;
+	rect.y2 = plane->state->fb->height;
+
+	hyperv_update_dirt(hv->hdev, &rect);
+}
+
 static const struct drm_plane_helper_funcs hyperv_plane_helper_funcs = {
 	DRM_GEM_SHADOW_PLANE_HELPER_FUNCS,
 	.atomic_check = hyperv_plane_atomic_check,
 	.atomic_update = hyperv_plane_atomic_update,
+	.get_scanout_buffer = hyperv_plane_get_scanout_buffer,
+	.panic_flush = hyperv_plane_panic_flush,
 };
 
 static const struct drm_plane_funcs hyperv_plane_funcs = {
-- 
2.49.0

Re: [PATCH RFC drm-misc-next v2 1/1] drm/hyperv: Add support for drm_panic

[Jocelyn Falempe]

On 26/05/2025 11:01, Ryosuke Yasuoka wrote:
> Add drm_panic module for hyperv drm so that panic screen can be
> displayed on panic.

Thanks, it looks good to me.

Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
> 
> Signed-off-by: Ryosuke Yasuoka <ryasuoka@redhat.com>
> ---
>   drivers/gpu/drm/hyperv/hyperv_drm_modeset.c | 36 +++++++++++++++++++++
>   1 file changed, 36 insertions(+)
> 
> diff --git a/drivers/gpu/drm/hyperv/hyperv_drm_modeset.c b/drivers/gpu/drm/hyperv/hyperv_drm_modeset.c
> index f7d2e973f79e..945b9482bcb3 100644
> --- a/drivers/gpu/drm/hyperv/hyperv_drm_modeset.c
> +++ b/drivers/gpu/drm/hyperv/hyperv_drm_modeset.c
> @@ -17,6 +17,7 @@
>   #include <drm/drm_gem_framebuffer_helper.h>
>   #include <drm/drm_gem_shmem_helper.h>
>   #include <drm/drm_probe_helper.h>
> +#include <drm/drm_panic.h>
>   #include <drm/drm_plane.h>
>   
>   #include "hyperv_drm.h"
> @@ -181,10 +182,45 @@ static void hyperv_plane_atomic_update(struct drm_plane *plane,
>   	}
>   }
>   
> +static int hyperv_plane_get_scanout_buffer(struct drm_plane *plane,
> +					   struct drm_scanout_buffer *sb)
> +{
> +	struct hyperv_drm_device *hv = to_hv(plane->dev);
> +	struct iosys_map map = IOSYS_MAP_INIT_VADDR_IOMEM(hv->vram);
> +
> +	if (plane->state && plane->state->fb) {
> +		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];
> +		sb->map[0] = map;
> +		return 0;
> +	}
> +	return -ENODEV;
> +}
> +
> +static void hyperv_plane_panic_flush(struct drm_plane *plane)
> +{
> +	struct hyperv_drm_device *hv = to_hv(plane->dev);
> +	struct drm_rect rect;
> +
> +	if (!plane->state || !plane->state->fb)
> +		return;
> +
> +	rect.x1 = 0;
> +	rect.y1 = 0;
> +	rect.x2 = plane->state->fb->width;
> +	rect.y2 = plane->state->fb->height;
> +
> +	hyperv_update_dirt(hv->hdev, &rect);
> +}
> +
>   static const struct drm_plane_helper_funcs hyperv_plane_helper_funcs = {
>   	DRM_GEM_SHADOW_PLANE_HELPER_FUNCS,
>   	.atomic_check = hyperv_plane_atomic_check,
>   	.atomic_update = hyperv_plane_atomic_update,
> +	.get_scanout_buffer = hyperv_plane_get_scanout_buffer,
> +	.panic_flush = hyperv_plane_panic_flush,
>   };
>   
>   static const struct drm_plane_funcs hyperv_plane_funcs = {

Re: [PATCH RFC drm-misc-next v2 1/1] drm/hyperv: Add support for drm_panic

[Jocelyn Falempe]

On 26/05/2025 11:01, Ryosuke Yasuoka wrote:
> Add drm_panic module for hyperv drm so that panic screen can be
> displayed on panic.

I've just pushed it to drm-misc-next.

Thanks for your contribution.

-- 

Jocelyn

> 
> Signed-off-by: Ryosuke Yasuoka <ryasuoka@redhat.com>
> ---
>   drivers/gpu/drm/hyperv/hyperv_drm_modeset.c | 36 +++++++++++++++++++++
>   1 file changed, 36 insertions(+)
> 
> diff --git a/drivers/gpu/drm/hyperv/hyperv_drm_modeset.c b/drivers/gpu/drm/hyperv/hyperv_drm_modeset.c
> index f7d2e973f79e..945b9482bcb3 100644
> --- a/drivers/gpu/drm/hyperv/hyperv_drm_modeset.c
> +++ b/drivers/gpu/drm/hyperv/hyperv_drm_modeset.c
> @@ -17,6 +17,7 @@
>   #include <drm/drm_gem_framebuffer_helper.h>
>   #include <drm/drm_gem_shmem_helper.h>
>   #include <drm/drm_probe_helper.h>
> +#include <drm/drm_panic.h>
>   #include <drm/drm_plane.h>
>   
>   #include "hyperv_drm.h"
> @@ -181,10 +182,45 @@ static void hyperv_plane_atomic_update(struct drm_plane *plane,
>   	}
>   }
>   
> +static int hyperv_plane_get_scanout_buffer(struct drm_plane *plane,
> +					   struct drm_scanout_buffer *sb)
> +{
> +	struct hyperv_drm_device *hv = to_hv(plane->dev);
> +	struct iosys_map map = IOSYS_MAP_INIT_VADDR_IOMEM(hv->vram);
> +
> +	if (plane->state && plane->state->fb) {
> +		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];
> +		sb->map[0] = map;
> +		return 0;
> +	}
> +	return -ENODEV;
> +}
> +
> +static void hyperv_plane_panic_flush(struct drm_plane *plane)
> +{
> +	struct hyperv_drm_device *hv = to_hv(plane->dev);
> +	struct drm_rect rect;
> +
> +	if (!plane->state || !plane->state->fb)
> +		return;
> +
> +	rect.x1 = 0;
> +	rect.y1 = 0;
> +	rect.x2 = plane->state->fb->width;
> +	rect.y2 = plane->state->fb->height;
> +
> +	hyperv_update_dirt(hv->hdev, &rect);
> +}
> +
>   static const struct drm_plane_helper_funcs hyperv_plane_helper_funcs = {
>   	DRM_GEM_SHADOW_PLANE_HELPER_FUNCS,
>   	.atomic_check = hyperv_plane_atomic_check,
>   	.atomic_update = hyperv_plane_atomic_update,
> +	.get_scanout_buffer = hyperv_plane_get_scanout_buffer,
> +	.panic_flush = hyperv_plane_panic_flush,
>   };
>   
>   static const struct drm_plane_funcs hyperv_plane_funcs = {