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([2a01:e0a:c:37e0:ced3:55bd:f454:e722]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-43eb5fcd3d7sm1973685e9.12.2025.04.01.15.27.07 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 01 Apr 2025 15:27:08 -0700 (PDT) Message-ID: Date: Wed, 2 Apr 2025 00:27:07 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 4/8] drm/i915/gem: Add i915_gem_object_panic_map() To: =?UTF-8?B?VmlsbGUgU3lyasOkbMOk?= Cc: Jani Nikula , Rodrigo Vivi , Joonas Lahtinen , Tvrtko Ursulin , David Airlie , Simona Vetter , intel-gfx@lists.freedesktop.org, intel-xe@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org References: <20250401125818.333033-1-jfalempe@redhat.com> <20250401125818.333033-5-jfalempe@redhat.com> Content-Language: en-US, fr From: Jocelyn Falempe In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 01/04/2025 19:47, Ville Syrjälä wrote: > On Tue, Apr 01, 2025 at 02:51:10PM +0200, Jocelyn Falempe wrote: >> Prepare the work for drm_panic support. This is used to map the >> current framebuffer, so the CPU can overwrite it with the panic >> message. >> >> Signed-off-by: Jocelyn Falempe >> --- >> >> v5: >> * Use iosys_map for intel_bo_panic_map(). >> >> drivers/gpu/drm/i915/display/intel_bo.c | 5 ++++ >> drivers/gpu/drm/i915/display/intel_bo.h | 1 + >> drivers/gpu/drm/i915/gem/i915_gem_object.h | 2 ++ >> drivers/gpu/drm/i915/gem/i915_gem_pages.c | 29 ++++++++++++++++++++++ >> drivers/gpu/drm/xe/display/intel_bo.c | 10 ++++++++ >> 5 files changed, 47 insertions(+) >> >> diff --git a/drivers/gpu/drm/i915/display/intel_bo.c b/drivers/gpu/drm/i915/display/intel_bo.c >> index fbd16d7b58d9..ac904e9ec7d5 100644 >> --- a/drivers/gpu/drm/i915/display/intel_bo.c >> +++ b/drivers/gpu/drm/i915/display/intel_bo.c >> @@ -57,3 +57,8 @@ void intel_bo_describe(struct seq_file *m, struct drm_gem_object *obj) >> { >> i915_debugfs_describe_obj(m, to_intel_bo(obj)); >> } >> + >> +void intel_bo_panic_map(struct drm_gem_object *obj, struct iosys_map *map) >> +{ >> + i915_gem_object_panic_map(to_intel_bo(obj), map); >> +} >> diff --git a/drivers/gpu/drm/i915/display/intel_bo.h b/drivers/gpu/drm/i915/display/intel_bo.h >> index ea7a2253aaa5..5b6c63d99786 100644 >> --- a/drivers/gpu/drm/i915/display/intel_bo.h >> +++ b/drivers/gpu/drm/i915/display/intel_bo.h >> @@ -23,5 +23,6 @@ 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); >> +void intel_bo_panic_map(struct drm_gem_object *obj, struct iosys_map *map); >> >> #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 a5f34542135c..b16092707ea5 100644 >> --- a/drivers/gpu/drm/i915/gem/i915_gem_object.h >> +++ b/drivers/gpu/drm/i915/gem/i915_gem_object.h >> @@ -692,6 +692,8 @@ 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); >> >> +void i915_gem_object_panic_map(struct drm_i915_gem_object *obj, struct iosys_map *map); >> + >> /** >> * 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 8780aa243105..718bea6474d7 100644 >> --- a/drivers/gpu/drm/i915/gem/i915_gem_pages.c >> +++ b/drivers/gpu/drm/i915/gem/i915_gem_pages.c >> @@ -355,6 +355,35 @@ static void *i915_gem_object_map_pfn(struct drm_i915_gem_object *obj, >> return vaddr ?: ERR_PTR(-ENOMEM); >> } >> >> +/* Map the current framebuffer for CPU access. Called from panic handler, so no >> + * need to pin or cleanup. >> + */ >> +void i915_gem_object_panic_map(struct drm_i915_gem_object *obj, struct iosys_map *map) >> +{ >> + enum i915_map_type has_type; >> + void *ptr; >> + >> + ptr = page_unpack_bits(obj->mm.mapping, &has_type); >> + >> + >> + if (!ptr) { >> + if (i915_gem_object_has_struct_page(obj)) >> + ptr = i915_gem_object_map_page(obj, I915_MAP_WB); >> + else >> + ptr = i915_gem_object_map_pfn(obj, I915_MAP_WB); > > WB mapping would require clflushing to make it to the display. > Is that being done somewhere? Yes, it's done in intel_panic_flush() in patch 5, otherwise the panic screen is not displayed. > >> + >> + if (IS_ERR(ptr)) >> + return; > > What happens when the mapping fails? In intel_get_scanout_buffer(), the iosys_map is cleared before calling this function. Then it checks iosys_map_is_null(), and returns an error if it is. I can add a comment, or I can change the function type to return an int, that would probably be cleaner. > >> + >> + obj->mm.mapping = page_pack_bits(ptr, I915_MAP_WB); >> + } >> + >> + if (i915_gem_object_has_iomem(obj)) >> + iosys_map_set_vaddr_iomem(map, (void __iomem *) ptr); >> + else >> + iosys_map_set_vaddr(map, ptr); >> +} >> + >> /* 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..c68166a64336 100644 >> --- a/drivers/gpu/drm/xe/display/intel_bo.c >> +++ b/drivers/gpu/drm/xe/display/intel_bo.c >> @@ -59,3 +59,13 @@ void intel_bo_describe(struct seq_file *m, struct drm_gem_object *obj) >> { >> /* FIXME */ >> } >> + >> +void intel_bo_panic_map(struct drm_gem_object *obj, struct iosys_map *map) >> +{ >> + struct xe_bo *bo = gem_to_xe_bo(obj); >> + int ret; >> + >> + ret = ttm_bo_vmap(&bo->ttm, map); >> + if (ret) >> + iosys_map_clear(map); >> +} >> -- >> 2.49.0 >