[PATCH v2] video: hyperv: hyperv_fb: refresh the VM screen by force on VM panic
From: Dexuan Cui <decui@microsoft.com>
Date: 2014-06-26 20:36:50
Currently the VSC has no chance to notify the VSP of the dirty rectangle on VM panic because the notification work is done in a workqueue, and in panic() the kernel typically ends up in an infinite loop, and a typical kernel config has CONFIG_PREEMPT_VOLUNTARY=y and CONFIG_PREEMPT is not set, so a context switch can't happen in panic() and the workqueue won't have a chance to run. As a result, the VM Connection window can't refresh until it's closed and we re-connect to the VM. We can register a handler on panic_notifier_list: the handler can notify the VSC and switch the framebuffer driver to a "synchronous mode", meaning the VSC flushes any future framebuffer change to the VSP immediately. v2: removed the MS-TFS line in the commit message Signed-off-by: Dexuan Cui <decui@microsoft.com> Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com> --- drivers/video/fbdev/hyperv_fb.c | 58 ++++++++++++++++++++++++++++++++++++++--- 1 file changed, 55 insertions(+), 3 deletions(-)
diff --git a/drivers/video/fbdev/hyperv_fb.c b/drivers/video/fbdev/hyperv_fb.c
index e23392e..291d171 100644
--- a/drivers/video/fbdev/hyperv_fb.c
+++ b/drivers/video/fbdev/hyperv_fb.c@@ -226,11 +226,16 @@ struct hvfb_par { u8 recv_buf[MAX_VMBUS_PKT_SIZE]; }; +static struct fb_info *hvfb_info; + static uint screen_width = HVFB_WIDTH; static uint screen_height = HVFB_HEIGHT; static uint screen_depth; static uint screen_fb_size; +/* If true, the VSC notifies the VSP on every framebuffer change */ +static bool synchronous_fb; + /* Send message to Hyper-V host */ static inline int synthvid_send(struct hv_device *hdev, struct synthvid_msg *msg)
@@ -532,6 +537,20 @@ static void hvfb_update_work(struct work_struct *w) schedule_delayed_work(&par->dwork, HVFB_UPDATE_DELAY); } +static int hvfb_on_panic(struct notifier_block *nb, + unsigned long e, void *p) +{ + if (hvfb_info) + synthvid_update(hvfb_info); + + synchronous_fb = true; + + return NOTIFY_DONE; +} + +static struct notifier_block hvfb_panic_nb = { + .notifier_call = hvfb_on_panic, +}; /* Framebuffer operation handlers */
@@ -582,14 +601,41 @@ static int hvfb_blank(int blank, struct fb_info *info) return 1; /* get fb_blank to set the colormap to all black */ } +static void hvfb_cfb_fillrect(struct fb_info *p, + const struct fb_fillrect *rect) +{ + cfb_fillrect(p, rect); + + if (unlikely(synchronous_fb)) + synthvid_update(p); +} + +static void hvfb_cfb_copyarea(struct fb_info *p, + const struct fb_copyarea *area) +{ + cfb_copyarea(p, area); + + if (unlikely(synchronous_fb)) + synthvid_update(p); +} + +static void hvfb_cfb_imageblit(struct fb_info *p, + const struct fb_image *image) +{ + cfb_imageblit(p, image); + + if (unlikely(synchronous_fb)) + synthvid_update(p); +} + static struct fb_ops hvfb_ops = { .owner = THIS_MODULE, .fb_check_var = hvfb_check_var, .fb_set_par = hvfb_set_par, .fb_setcolreg = hvfb_setcolreg, - .fb_fillrect = cfb_fillrect, - .fb_copyarea = cfb_copyarea, - .fb_imageblit = cfb_imageblit, + .fb_fillrect = hvfb_cfb_fillrect, + .fb_copyarea = hvfb_cfb_copyarea, + .fb_imageblit = hvfb_cfb_imageblit, .fb_blank = hvfb_blank, };
@@ -801,6 +847,9 @@ static int hvfb_probe(struct hv_device *hdev, par->fb_ready = true; + hvfb_info = info; + atomic_notifier_chain_register(&panic_notifier_list, &hvfb_panic_nb); + return 0; error:
@@ -820,6 +869,9 @@ static int hvfb_remove(struct hv_device *hdev) struct fb_info *info = hv_get_drvdata(hdev); struct hvfb_par *par = info->par; + atomic_notifier_chain_unregister(&panic_notifier_list, &hvfb_panic_nb); + hvfb_info = NULL; + par->update = false; par->fb_ready = false;
--
1.9.1