Implement virglrenderer backend for virtio-gpu

Follow the installation guide from:
https://gitlab.freedesktop.org/virgl/virglrenderer

Prerequisite:
`sudo apt install libepoxy-dev`

Author: shengwen-tw

Makefile

@@ -128,30 +128,53 @@ endif
 
 # virtio-gpu
 ENABLE_VIRTIOGPU ?= 1
-ifneq ($(UNAME_S),Linux)
-    ENABLE_VIRTIOGPU := 0
-endif
+
+# Enable 3D acceleration for virtio-gpu using virglrenderer.
+# When set to 1, virtio-gpu uses the virglrenderer backend instead of the software
+# renderer.
+ENABLE_VIRGL ?= 1
 
 # SDL2
 ENABLE_SDL ?= 1
 ifeq (, $(shell which sdl2-config))
     $(warning No sdl2-config in $$PATH. Check SDL2 installation in advance)
     override ENABLE_SDL := 0
 endif
-
 ifeq ($(ENABLE_SDL),1)
     CFLAGS += $(shell sdl2-config --cflags)
     LDFLAGS += $(shell sdl2-config --libs)
 else
+    # Disable virtio-gpu and virgl if SDL is not set
     override ENABLE_VIRTIOGPU := 0
+    override ENABLE_VIRGL := 0
 endif
 
+# virtio-gpu
+ifneq ($(UNAME_S),Linux)
+    ENABLE_VIRTIOGPU := 0
+endif
 ifeq ($(ENABLE_VIRTIOGPU),1)
-    OBJS_EXTRA += window.o
+    OBJS_EXTRA += window-events.o
     OBJS_EXTRA += virtio-gpu.o
+else
+    override ENABLE_VIRGL := 0
+endif
+
+# VirGL
+ifeq ($(ENABLE_VIRGL),1)
+    CFLAGS += $(shell pkg-config virglrenderer gl egl epoxy --cflags)
+    LDFLAGS += $(shell pkg-config virglrenderer gl egl epoxy --libs)
+    OBJS_EXTRA += virgl.o
+    OBJS_EXTRA += window-gl.o
+else
+ifeq ($(ENABLE_VIRTIOGPU),1)
+    OBJS_EXTRA += virtio-gpu-sw.o
+    OBJS_EXTRA += window-sw.o
+endif
 endif
 
 $(call set-feature, VIRTIOGPU)
+$(call set-feature, VIRGL)
 
 BIN = semu
 all: $(BIN) minimal.dtb

common.h

@@ -1,5 +1,9 @@
 #pragma once
 
+#include <stddef.h>
+#include <stdint.h>
+#include <sys/uio.h>
+
 #include "feature.h"
 
 #define BITS_PER_CHAR 8

device.h

@@ -270,8 +270,6 @@ void virtio_gpu_write(hart_t *vm,
                       uint8_t width,
                       uint32_t value);
 
-void semu_virgl_init(virtio_gpu_state_t *vgpu);
-
 void virtio_gpu_init(virtio_gpu_state_t *vgpu);
 void virtio_gpu_add_scanout(virtio_gpu_state_t *vgpu,
                             uint32_t width,

feature.h

@@ -22,6 +22,11 @@
 #define SEMU_FEATURE_VIRTIOGPU 1
 #endif
 
+/* VirGL */
+#ifndef SEMU_FEATURE_VIRGL
+#define SEMU_FEATURE_VIRGL 1
+#endif
+
 /* virtio-input */
 #ifndef SEMU_FEATURE_VIRTIOINPUT
 #define SEMU_FEATURE_VIRTIOINPUT 1

main.c

@@ -13,10 +13,13 @@
 #include "mini-gdbstub/include/gdbstub.h"
 #include "riscv.h"
 #include "riscv_private.h"
+#include "virgl.h"
 #include "window.h"
 
 #define PRIV(x) ((emu_state_t *) x->priv)
 
+extern const struct window_backend g_window;
+
 /* Define fetch separately since it is simpler (fixed width, already checked
  * alignment, only main RAM is executable).
  */
@@ -760,19 +763,23 @@ static int semu_init(emu_state_t *emu, int argc, char **argv)
         fprintf(stderr, "No virtio-snd functioned\n");
     emu->vsnd.ram = emu->ram;
 #endif
-#if SEMU_HAS(VIRTIOGPU)
-    emu->vgpu.ram = emu->ram;
-    virtio_gpu_init(&(emu->vgpu));
-    virtio_gpu_add_scanout(&(emu->vgpu), 1024, 768);
-    window_init();
-#endif
 #if SEMU_HAS(VIRTIOINPUT)
     emu->vkeyboard.ram = emu->ram;
     virtio_input_init(&(emu->vkeyboard));
 
     emu->vmouse.ram = emu->ram;
     virtio_input_init(&(emu->vmouse));
 #endif
+#if SEMU_HAS(VIRTIOGPU)
+    emu->vgpu.ram = emu->ram;
+    virtio_gpu_init(&(emu->vgpu));
+    virtio_gpu_add_scanout(&(emu->vgpu), 1024, 768);
+
+    g_window.window_init();
+#endif
+#if SEMU_HAS(VIRGL)
+    semu_virgl_init(&(emu->vgpu));
+#endif
 
     emu->peripheral_update_ctr = 0;
     emu->debug = debug;
@@ -823,6 +830,10 @@ static int semu_step(emu_state_t *emu)
             if (emu->vmouse.InterruptStatus)
                 emu_update_vinput_mouse_interrupts(vm);
 #endif
+
+#if SEMU_HAS(VIRGL)
+            semu_virgl_fence_poll();
+#endif
         }
 
         emu_update_timer_interrupt(vm->hart[i]);