[PATCH v8 5/9] drm/i915: Add intel_bo_panic_setup and intel_bo_panic_finish
Jocelyn Falempe
jfalempe at redhat.com
Fri Jun 6 11:48:09 UTC 2025
Implement both functions for i915 and xe, they prepare the work for
drm_panic support.
They both use kmap_try_from_panic(), and map one page at a time, to
write the panic screen on the framebuffer.
Signed-off-by: Jocelyn Falempe <jfalempe at redhat.com>
---
v5:
* Use iosys_map for intel_bo_panic_map().
v7:
* Return int for i915_gem_object_panic_map() (Ville Syrjälä)
v8:
* Complete rewrite, to use kmap_try_from_panic() which is safe
to call from a panic handler
drivers/gpu/drm/i915/display/intel_bo.c | 11 +++
drivers/gpu/drm/i915/display/intel_bo.h | 3 +
drivers/gpu/drm/i915/gem/i915_gem_object.h | 4 +
drivers/gpu/drm/i915/gem/i915_gem_pages.c | 92 ++++++++++++++++++++++
drivers/gpu/drm/xe/display/intel_bo.c | 55 +++++++++++++
5 files changed, 165 insertions(+)
diff --git a/drivers/gpu/drm/i915/display/intel_bo.c b/drivers/gpu/drm/i915/display/intel_bo.c
index fbd16d7b58d9..83dbd8ae16fe 100644
--- a/drivers/gpu/drm/i915/display/intel_bo.c
+++ b/drivers/gpu/drm/i915/display/intel_bo.c
@@ -1,6 +1,7 @@
// SPDX-License-Identifier: MIT
/* Copyright © 2024 Intel Corporation */
+#include <drm/drm_panic.h>
#include "gem/i915_gem_mman.h"
#include "gem/i915_gem_object.h"
#include "gem/i915_gem_object_frontbuffer.h"
@@ -57,3 +58,13 @@ void intel_bo_describe(struct seq_file *m, struct drm_gem_object *obj)
{
i915_debugfs_describe_obj(m, to_intel_bo(obj));
}
+
+int intel_bo_panic_setup(struct drm_gem_object *obj, struct drm_scanout_buffer *sb)
+{
+ return i915_gem_object_panic_setup(to_intel_bo(obj), sb);
+}
+
+void intel_bo_panic_finish(struct drm_gem_object *obj)
+{
+ return i915_gem_object_panic_finish(to_intel_bo(obj));
+}
diff --git a/drivers/gpu/drm/i915/display/intel_bo.h b/drivers/gpu/drm/i915/display/intel_bo.h
index ea7a2253aaa5..9ac087ea275d 100644
--- a/drivers/gpu/drm/i915/display/intel_bo.h
+++ b/drivers/gpu/drm/i915/display/intel_bo.h
@@ -4,6 +4,7 @@
#ifndef __INTEL_BO__
#define __INTEL_BO__
+#include <drm/drm_panic.h>
#include <linux/types.h>
struct drm_gem_object;
@@ -23,5 +24,7 @@ struct intel_frontbuffer *intel_bo_set_frontbuffer(struct drm_gem_object *obj,
struct intel_frontbuffer *front);
void intel_bo_describe(struct seq_file *m, struct drm_gem_object *obj);
+int intel_bo_panic_setup(struct drm_gem_object *obj, struct drm_scanout_buffer *sb);
+void intel_bo_panic_finish(struct drm_gem_object *obj);
#endif /* __INTEL_BO__ */
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.h b/drivers/gpu/drm/i915/gem/i915_gem_object.h
index c34f41605b46..9a0c1019dcad 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_object.h
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object.h
@@ -9,6 +9,7 @@
#include <drm/drm_gem.h>
#include <drm/drm_file.h>
#include <drm/drm_device.h>
+#include <drm/drm_panic.h>
#include "intel_memory_region.h"
#include "i915_gem_object_types.h"
@@ -691,6 +692,9 @@ i915_gem_object_unpin_pages(struct drm_i915_gem_object *obj)
int __i915_gem_object_put_pages(struct drm_i915_gem_object *obj);
int i915_gem_object_truncate(struct drm_i915_gem_object *obj);
+int i915_gem_object_panic_setup(struct drm_i915_gem_object *obj, struct drm_scanout_buffer *sb);
+void i915_gem_object_panic_finish(struct drm_i915_gem_object *obj);
+
/**
* i915_gem_object_pin_map - return a contiguous mapping of the entire object
* @obj: the object to map into kernel address space
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_pages.c b/drivers/gpu/drm/i915/gem/i915_gem_pages.c
index 7f83f8bdc8fb..9bdbac3d9433 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_pages.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_pages.c
@@ -3,6 +3,7 @@
* Copyright © 2014-2016 Intel Corporation
*/
+#include <drm/drm_panic.h>
#include <drm/drm_cache.h>
#include <linux/vmalloc.h>
@@ -354,6 +355,97 @@ static void *i915_gem_object_map_pfn(struct drm_i915_gem_object *obj,
return vaddr ?: ERR_PTR(-ENOMEM);
}
+static struct page **i915_panic_pages;
+static int i915_panic_page = -1;
+static void *i915_panic_vaddr;
+
+static void i915_panic_kunmap(void)
+{
+ if (i915_panic_vaddr) {
+ drm_clflush_virt_range(i915_panic_vaddr, PAGE_SIZE);
+ kunmap_local(i915_panic_vaddr);
+ i915_panic_vaddr = NULL;
+ }
+}
+
+static struct page **i915_gem_object_panic_pages(struct drm_i915_gem_object *obj)
+{
+ unsigned long n_pages = obj->base.size >> PAGE_SHIFT, i;
+ struct page *page;
+ struct page **pages;
+ struct sgt_iter iter;
+
+ pages = kvmalloc_array(n_pages, sizeof(*pages), GFP_ATOMIC);
+ if (!pages)
+ return NULL;
+
+ i = 0;
+ for_each_sgt_page(page, iter, obj->mm.pages)
+ pages[i++] = page;
+ return pages;
+}
+
+/*
+ * The scanout buffer pages are not mapped, so for each pixel,
+ * use kmap_local_page_try_from_panic() to map the page, and write the pixel.
+ * Try to keep the map from the previous pixel, to avoid too much map/unmap.
+ */
+static void i915_gem_object_panic_page_set_pixel(struct drm_scanout_buffer *sb, unsigned int x,
+ unsigned int y, u32 color)
+{
+ unsigned int new_page;
+ unsigned int offset;
+
+ offset = y * sb->pitch[0] + x * sb->format->cpp[0];
+
+ new_page = offset >> PAGE_SHIFT;
+ offset = offset % PAGE_SIZE;
+ if (new_page != i915_panic_page) {
+ i915_panic_kunmap();
+ i915_panic_page = new_page;
+ i915_panic_vaddr = kmap_local_page_try_from_panic(
+ i915_panic_pages[i915_panic_page]);
+ }
+ if (i915_panic_vaddr) {
+ u32 *pix = i915_panic_vaddr + offset;
+ *pix = color;
+ }
+}
+
+/*
+ * Setup the gem framebuffer for drm_panic access.
+ * Use current vaddr if it exists, or setup a list of pages.
+ * pfn is not supported yet.
+ */
+int i915_gem_object_panic_setup(struct drm_i915_gem_object *obj, struct drm_scanout_buffer *sb)
+{
+ enum i915_map_type has_type;
+ void *ptr;
+
+ ptr = page_unpack_bits(obj->mm.mapping, &has_type);
+ if (ptr) {
+ if (i915_gem_object_has_iomem(obj))
+ iosys_map_set_vaddr_iomem(&sb->map[0], (void __iomem *)ptr);
+ else
+ iosys_map_set_vaddr(&sb->map[0], ptr);
+
+ return 0;
+ }
+ if (i915_gem_object_has_struct_page(obj)) {
+ i915_panic_pages = i915_gem_object_panic_pages(obj);
+ sb->set_pixel = i915_gem_object_panic_page_set_pixel;
+ i915_panic_page = -1;
+ return 0;
+ }
+ return -EOPNOTSUPP;
+}
+
+void i915_gem_object_panic_finish(struct drm_i915_gem_object *obj)
+{
+ i915_panic_kunmap();
+ i915_panic_page = -1;
+}
+
/* get, pin, and map the pages of the object into kernel space */
void *i915_gem_object_pin_map(struct drm_i915_gem_object *obj,
enum i915_map_type type)
diff --git a/drivers/gpu/drm/xe/display/intel_bo.c b/drivers/gpu/drm/xe/display/intel_bo.c
index 27437c22bd70..eb9a3400c110 100644
--- a/drivers/gpu/drm/xe/display/intel_bo.c
+++ b/drivers/gpu/drm/xe/display/intel_bo.c
@@ -1,6 +1,7 @@
// SPDX-License-Identifier: MIT
/* Copyright © 2024 Intel Corporation */
+#include <drm/drm_cache.h>
#include <drm/drm_gem.h>
#include "xe_bo.h"
@@ -59,3 +60,57 @@ void intel_bo_describe(struct seq_file *m, struct drm_gem_object *obj)
{
/* FIXME */
}
+
+static int xe_panic_page = -1;
+static void *xe_panic_vaddr;
+static struct xe_bo *xe_panic_bo;
+
+static void xe_panic_kunmap(void)
+{
+ if (xe_panic_vaddr) {
+ drm_clflush_virt_range(xe_panic_vaddr, PAGE_SIZE);
+ kunmap_local(xe_panic_vaddr);
+ xe_panic_vaddr = NULL;
+ }
+}
+/*
+ * The scanout buffer pages are not mapped, so for each pixel,
+ * use kmap_local_page_try_from_panic() to map the page, and write the pixel.
+ * Try to keep the map from the previous pixel, to avoid too much map/unmap.
+ */
+static void xe_panic_page_set_pixel(struct drm_scanout_buffer *sb, unsigned int x,
+ unsigned int y, u32 color)
+{
+ unsigned int new_page;
+ unsigned int offset;
+
+ offset = y * sb->pitch[0] + x * sb->format->cpp[0];
+
+ new_page = offset >> PAGE_SHIFT;
+ offset = offset % PAGE_SIZE;
+ if (new_page != xe_panic_page) {
+ xe_panic_kunmap();
+ xe_panic_page = new_page;
+ xe_panic_vaddr = ttm_bo_kmap_try_from_panic(&xe_panic_bo->ttm,
+ xe_panic_page);
+ }
+ if (xe_panic_vaddr) {
+ u32 *pix = xe_panic_vaddr + offset;
+ *pix = color;
+ }
+}
+
+int intel_bo_panic_setup(struct drm_gem_object *obj, struct drm_scanout_buffer *sb)
+{
+ struct xe_bo *bo = gem_to_xe_bo(obj);
+
+ xe_panic_bo = bo;
+ sb->set_pixel = xe_panic_page_set_pixel;
+ return 0;
+}
+
+void intel_bo_panic_finish(struct drm_gem_object *obj)
+{
+ xe_panic_kunmap();
+ xe_panic_page = -1;
+}
--
2.49.0
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