[QEMU PATCH v4 1/1] virtgpu: do not destroy resources when guest suspend

[Jiqian Chen <Jiqian.Chen@xxxxxxx>]

After suspending and resuming guest VM, you will get
a black screen, and the display can't come back.

This is because when guest did suspending, it called
into qemu to call virtio_gpu_gl_reset. In function
virtio_gpu_gl_reset, it destroyed resources and reset
renderer, which were used for display. As a result,
guest's screen can't come back to the time when it was
suspended and only showed black.

So, this patch adds a new ctrl message
VIRTIO_GPU_CMD_SET_FREEZE_MODE to get notifications from
guest. If guest is during suspending, it sets freeze mode
of virtgpu to freeze_S3, this will prevent destroying
resources and resetting renderer when guest calls into
virtio_gpu_gl_reset. If guest is during resuming, it sets
freeze mode to unfreeze, and then virtio_gpu_gl_reset
will keep its origin actions and has no other impaction.

Due to this implemention needs cooperation with guest,
so it added a new feature flag VIRTIO_GPU_F_FREEZE_S3, so
that guest and host can negotiate whenever freeze_S3 is
supported or not.

Signed-off-by: Jiqian Chen <Jiqian.Chen@xxxxxxx>
---
 hw/display/virtio-gpu-base.c   |  3 ++
 hw/display/virtio-gpu-gl.c     | 10 ++++++-
 hw/display/virtio-gpu-virgl.c  |  7 +++++
 hw/display/virtio-gpu.c        | 55 ++++++++++++++++++++++++++++++++--
 hw/virtio/virtio.c             |  3 ++
 include/hw/virtio/virtio-gpu.h |  6 ++++
 6 files changed, 81 insertions(+), 3 deletions(-)

diff --git a/hw/display/virtio-gpu-base.c b/hw/display/virtio-gpu-base.c
index a29f191aa8..40ae4f9678 100644
--- a/hw/display/virtio-gpu-base.c
+++ b/hw/display/virtio-gpu-base.c
@@ -215,6 +215,9 @@ virtio_gpu_base_get_features(VirtIODevice *vdev, uint64_t 
features,
     if (virtio_gpu_blob_enabled(g->conf)) {
         features |= (1 << VIRTIO_GPU_F_RESOURCE_BLOB);
     }
+    if (virtio_gpu_freeze_S3_enabled(g->conf)) {
+        features |= (1 << VIRTIO_GPU_F_FREEZE_S3);
+    }
 
     return features;
 }
diff --git a/hw/display/virtio-gpu-gl.c b/hw/display/virtio-gpu-gl.c
index e06be60dfb..cb418dae9a 100644
--- a/hw/display/virtio-gpu-gl.c
+++ b/hw/display/virtio-gpu-gl.c
@@ -100,7 +100,15 @@ static void virtio_gpu_gl_reset(VirtIODevice *vdev)
      */
     if (gl->renderer_inited && !gl->renderer_reset) {
         virtio_gpu_virgl_reset_scanout(g);
-        gl->renderer_reset = true;
+        /*
+         * If guest is suspending, we shouldn't reset renderer,
+         * otherwise, the display can't come back to the time when
+         * it was suspended after guest was resumed.
+         */
+        if (!virtio_gpu_freeze_S3_enabled(g->parent_obj.conf) ||
+            g->freeze_mode == VIRTIO_GPU_FREEZE_MODE_UNFREEZE) {
+            gl->renderer_reset = true;
+        }
     }
 }
 
diff --git a/hw/display/virtio-gpu-virgl.c b/hw/display/virtio-gpu-virgl.c
index 73cb92c8d5..fc1971be70 100644
--- a/hw/display/virtio-gpu-virgl.c
+++ b/hw/display/virtio-gpu-virgl.c
@@ -464,6 +464,13 @@ void virtio_gpu_virgl_process_cmd(VirtIOGPU *g,
     case VIRTIO_GPU_CMD_GET_EDID:
         virtio_gpu_get_edid(g, cmd);
         break;
+    case VIRTIO_GPU_CMD_SET_FREEZE_MODE:
+        if (virtio_gpu_freeze_S3_enabled(g->parent_obj.conf)) {
+            virtio_gpu_cmd_set_freeze_mode(g, cmd);
+        } else {
+            cmd->error = VIRTIO_GPU_RESP_ERR_INVALID_PARAMETER;
+        }
+        break;
     default:
         cmd->error = VIRTIO_GPU_RESP_ERR_UNSPEC;
         break;
diff --git a/hw/display/virtio-gpu.c b/hw/display/virtio-gpu.c
index 5e15c79b94..dcf83379a8 100644
--- a/hw/display/virtio-gpu.c
+++ b/hw/display/virtio-gpu.c
@@ -373,6 +373,16 @@ static void virtio_gpu_resource_create_blob(VirtIOGPU *g,
     QTAILQ_INSERT_HEAD(&g->reslist, res, next);
 }
 
+void virtio_gpu_cmd_set_freeze_mode(VirtIOGPU *g,
+                         struct virtio_gpu_ctrl_command *cmd)
+{
+    struct virtio_gpu_set_freeze_mode sf;
+
+    VIRTIO_GPU_FILL_CMD(sf);
+    virtio_gpu_bswap_32(&sf, sizeof(sf));
+    g->freeze_mode = sf.freeze_mode;
+}
+
 static void virtio_gpu_disable_scanout(VirtIOGPU *g, int scanout_id)
 {
     struct virtio_gpu_scanout *scanout = &g->parent_obj.scanout[scanout_id];
@@ -986,6 +996,13 @@ void virtio_gpu_simple_process_cmd(VirtIOGPU *g,
     case VIRTIO_GPU_CMD_RESOURCE_DETACH_BACKING:
         virtio_gpu_resource_detach_backing(g, cmd);
         break;
+    case VIRTIO_GPU_CMD_SET_FREEZE_MODE:
+        if (virtio_gpu_freeze_S3_enabled(g->parent_obj.conf)) {
+            virtio_gpu_cmd_set_freeze_mode(g, cmd);
+        } else {
+            cmd->error = VIRTIO_GPU_RESP_ERR_INVALID_PARAMETER;
+        }
+        break;
     default:
         cmd->error = VIRTIO_GPU_RESP_ERR_UNSPEC;
         break;
@@ -1344,6 +1361,29 @@ void virtio_gpu_device_realize(DeviceState *qdev, Error 
**errp)
     QTAILQ_INIT(&g->reslist);
     QTAILQ_INIT(&g->cmdq);
     QTAILQ_INIT(&g->fenceq);
+
+    g->freeze_mode = VIRTIO_GPU_FREEZE_MODE_UNFREEZE;
+}
+
+static void virtio_gpu_device_unrealize(DeviceState *qdev)
+{
+    VirtIOGPU *g = VIRTIO_GPU(qdev);
+    struct virtio_gpu_simple_resource *res, *tmp;
+
+    /*
+     * This is to prevent memory leak in the situation that qemu is
+     * destroyed when guest is suspended. This also need hot-plug
+     * support.
+     */
+    if (virtio_gpu_freeze_S3_enabled(g->parent_obj.conf) &&
+        g->freeze_mode == VIRTIO_GPU_FREEZE_MODE_FREEZE_S3) {
+        QTAILQ_FOREACH_SAFE(res, &g->reslist, next, tmp) {
+            virtio_gpu_resource_destroy(g, res);
+        }
+        virtio_gpu_virgl_reset(g);
+        g->freeze_mode = VIRTIO_GPU_FREEZE_MODE_UNFREEZE;
+    }
+
 }
 
 void virtio_gpu_reset(VirtIODevice *vdev)
@@ -1352,8 +1392,16 @@ void virtio_gpu_reset(VirtIODevice *vdev)
     struct virtio_gpu_simple_resource *res, *tmp;
     struct virtio_gpu_ctrl_command *cmd;
 
-    QTAILQ_FOREACH_SAFE(res, &g->reslist, next, tmp) {
-        virtio_gpu_resource_destroy(g, res);
+    /*
+     * If guest is suspending, we shouldn't destroy resources,
+     * otherwise, the display can't come back to the time when
+     * it was suspended after guest was resumed.
+     */
+    if (!virtio_gpu_freeze_S3_enabled(g->parent_obj.conf) ||
+        g->freeze_mode == VIRTIO_GPU_FREEZE_MODE_UNFREEZE) {
+        QTAILQ_FOREACH_SAFE(res, &g->reslist, next, tmp) {
+            virtio_gpu_resource_destroy(g, res);
+        }
     }
 
     while (!QTAILQ_EMPTY(&g->cmdq)) {
@@ -1425,6 +1473,8 @@ static Property virtio_gpu_properties[] = {
                      256 * MiB),
     DEFINE_PROP_BIT("blob", VirtIOGPU, parent_obj.conf.flags,
                     VIRTIO_GPU_FLAG_BLOB_ENABLED, false),
+    DEFINE_PROP_BIT("freeze_S3", VirtIOGPU, parent_obj.conf.flags,
+                    VIRTIO_GPU_FLAG_FREEZE_S3_ENABLED, false),
     DEFINE_PROP_END_OF_LIST(),
 };
 
@@ -1441,6 +1491,7 @@ static void virtio_gpu_class_init(ObjectClass *klass, 
void *data)
     vgbc->gl_flushed = virtio_gpu_handle_gl_flushed;
 
     vdc->realize = virtio_gpu_device_realize;
+    vdc->unrealize = virtio_gpu_device_unrealize;
     vdc->reset = virtio_gpu_reset;
     vdc->get_config = virtio_gpu_get_config;
     vdc->set_config = virtio_gpu_set_config;
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index eb6347ab5d..2a3c54f2c4 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -240,6 +240,9 @@ qmp_virtio_feature_map_t virtio_gpu_feature_map[] = {
     FEATURE_ENTRY(VIRTIO_GPU_F_CONTEXT_INIT, \
             "VIRTIO_GPU_F_CONTEXT_INIT: Context types and synchronization "
             "timelines supported"),
+    FEATURE_ENTRY(VIRTIO_GPU_F_FREEZE_S3, \
+            "VIRTIO_GPU_F_FREEZE_S3: Freezing virtio-gpu and keeping resources"
+            "alive is supported."),
     FEATURE_ENTRY(VHOST_F_LOG_ALL, \
             "VHOST_F_LOG_ALL: Logging write descriptors supported"),
     FEATURE_ENTRY(VHOST_USER_F_PROTOCOL_FEATURES, \
diff --git a/include/hw/virtio/virtio-gpu.h b/include/hw/virtio/virtio-gpu.h
index 2e28507efe..141c48080f 100644
--- a/include/hw/virtio/virtio-gpu.h
+++ b/include/hw/virtio/virtio-gpu.h
@@ -90,6 +90,7 @@ enum virtio_gpu_base_conf_flags {
     VIRTIO_GPU_FLAG_EDID_ENABLED,
     VIRTIO_GPU_FLAG_DMABUF_ENABLED,
     VIRTIO_GPU_FLAG_BLOB_ENABLED,
+    VIRTIO_GPU_FLAG_FREEZE_S3_ENABLED,
 };
 
 #define virtio_gpu_virgl_enabled(_cfg) \
@@ -102,6 +103,8 @@ enum virtio_gpu_base_conf_flags {
     (_cfg.flags & (1 << VIRTIO_GPU_FLAG_DMABUF_ENABLED))
 #define virtio_gpu_blob_enabled(_cfg) \
     (_cfg.flags & (1 << VIRTIO_GPU_FLAG_BLOB_ENABLED))
+#define virtio_gpu_freeze_S3_enabled(_cfg) \
+    (_cfg.flags & (1 << VIRTIO_GPU_FLAG_FREEZE_S3_ENABLED))
 
 struct virtio_gpu_base_conf {
     uint32_t max_outputs;
@@ -173,6 +176,7 @@ struct VirtIOGPU {
 
     uint64_t hostmem;
 
+    virtio_gpu_freeze_mode_t freeze_mode;
     bool processing_cmdq;
     QEMUTimer *fence_poll;
     QEMUTimer *print_stats;
@@ -284,5 +288,7 @@ void virtio_gpu_virgl_reset_scanout(VirtIOGPU *g);
 void virtio_gpu_virgl_reset(VirtIOGPU *g);
 int virtio_gpu_virgl_init(VirtIOGPU *g);
 int virtio_gpu_virgl_get_num_capsets(VirtIOGPU *g);
+void virtio_gpu_cmd_set_freeze_mode(VirtIOGPU *g,
+                         struct virtio_gpu_ctrl_command *cmd);
 
 #endif
-- 
2.34.1