Bug 1715902 - Refuse WebRender on Linux if backed by software driver. r=jrmuizel

Reject software rasterizers on Linux (except Software WebRender) when
trying to create full WebRender, unless WebRender was force enabled.

Differential Revision: https://phabricator.services.mozilla.com/D117534

gfx/config/gfxVars.h

@@ -76,7 +76,8 @@ class gfxVarReceiver;
   _(UseAHardwareBufferSharedSurface, bool, false)                  \
   _(UseEGL, bool, false)                                           \
   _(DrmRenderDevice, nsCString, nsCString())                       \
-  _(UseDMABuf, bool, false)
+  _(UseDMABuf, bool, false)                                        \
+  _(WebRenderRequiresHardwareDriver, bool, false)
 
 /* Add new entries above this line. */
 

gfx/thebes/gfxPlatform.cpp

@@ -2673,6 +2673,15 @@ void gfxPlatform::InitWebRenderConfig() {
   bool hasSoftware = gfxConfig::IsEnabled(Feature::WEBRENDER_SOFTWARE);
   bool hasWebRender = hasHardware || hasSoftware;
 
+#ifdef MOZ_WIDGET_GTK
+  // We require a hardware driver to back the GL context unless the user forced
+  // on WebRender.
+  if (!gfxConfig::IsForcedOnByUser(Feature::WEBRENDER) &&
+      StaticPrefs::gfx_webrender_reject_software_driver_AtStartup()) {
+    gfxVars::SetWebRenderRequiresHardwareDriver(true);
+  }
+#endif
+
 #ifdef XP_WIN
   if (gfxConfig::IsEnabled(Feature::WEBRENDER_ANGLE)) {
     gfxVars::SetUseWebRenderANGLE(hasWebRender);

gfx/webrender_bindings/WebRenderAPI.cpp

@@ -167,7 +167,8 @@ class NewRenderer : public RendererEvent {
             compositor->ShouldDrawPreviousPartialPresentRegions(), mDocHandle,
             &wrRenderer, mMaxTextureSize, &errorMessage,
             StaticPrefs::gfx_webrender_enable_gpu_markers_AtStartup(),
-            panic_on_gl_error, picTileWidth, picTileHeight)) {
+            panic_on_gl_error, picTileWidth, picTileHeight,
+            gfx::gfxVars::WebRenderRequiresHardwareDriver())) {
       // wr_window_new puts a message into gfxCriticalNote if it returns false
       MOZ_ASSERT(errorMessage);
       mError->AssignASCII(errorMessage);

gfx/webrender_bindings/src/bindings.rs

@@ -1501,6 +1501,7 @@ pub extern "C" fn wr_window_new(
     panic_on_gl_error: bool,
     picture_tile_width: i32,
     picture_tile_height: i32,
+    reject_software_rasterizer: bool,
 ) -> bool {
     assert!(unsafe { is_in_render_thread() });
 
@@ -1646,6 +1647,7 @@ pub extern "C" fn wr_window_new(
         panic_on_gl_error,
         picture_tile_size,
         texture_cache_config,
+        reject_software_rasterizer,
         ..Default::default()
     };
 

gfx/wr/webrender/src/renderer/mod.rs

@@ -854,6 +854,7 @@ pub enum RendererError {
     Thread(std::io::Error),
     Resource(ResourceCacheError),
     MaxTextureSize,
+    SoftwareRasterizer,
 }
 
 impl From<ShaderError> for RendererError {
@@ -960,6 +961,13 @@ impl Renderer {
             max_internal_texture_size = max_internal_texture_size.min(internal_limit);
         }
 
+        if options.reject_software_rasterizer {
+          let renderer_name_lc = device.get_capabilities().renderer_name.to_lowercase();
+          if renderer_name_lc.contains("llvmpipe") || renderer_name_lc.contains("softpipe") || renderer_name_lc.contains("software rasterizer") {
+            return Err(RendererError::SoftwareRasterizer);
+          }
+        }
+
         let image_tiling_threshold = options.image_tiling_threshold
             .min(max_internal_texture_size);
 
@@ -5363,6 +5371,9 @@ pub struct RendererOptions {
     /// If false, we'll duplicate the instance attributes per vertex and issue
     /// regular indexed draws instead.
     pub enable_instancing: bool,
+    /// If true, we'll reject contexts backed by a software rasterizer, except
+    /// Software WebRender.
+    pub reject_software_rasterizer: bool,
 }
 
 impl RendererOptions {
@@ -5429,6 +5440,7 @@ impl Default for RendererOptions {
             // Disabling instancing means more vertex data to upload and potentially
             // process by the vertex shaders.
             enable_instancing: true,
+            reject_software_rasterizer: false,
         }
     }
 }

modules/libpref/init/StaticPrefList.yaml

@@ -4940,6 +4940,13 @@
   value: false
   mirror: once
 
+#ifdef MOZ_WIDGET_GTK
+- name: gfx.webrender.reject-software-driver
+  type: bool
+  value: true
+  mirror: once
+#endif
+
 - name: gfx.webrender.highlight-painted-layers
   type: RelaxedAtomicBool
   value: false