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
v3: remove some 'unlikely' markings
v4: avoid global variables as Tomi Valkeinen suggested
Cc: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
Signed-off-by: Dexuan Cui <decui@xxxxxxxxxxxxx>
---
drivers/video/fbdev/hyperv_fb.c | 62 +++++++++++++++++++++++++++++++++++++++--
1 file changed, 59 insertions(+), 3 deletions(-)
diff --git a/drivers/video/fbdev/hyperv_fb.c b/drivers/video/fbdev/hyperv_fb.c
index e23392e..569e756 100644
--- a/drivers/video/fbdev/hyperv_fb.c
+++ b/drivers/video/fbdev/hyperv_fb.c
@@ -224,6 +224,11 @@ struct hvfb_par {
u32 pseudo_palette[16];
u8 init_buf[MAX_VMBUS_PKT_SIZE];
u8 recv_buf[MAX_VMBUS_PKT_SIZE];
+
+ /* If true, the VSC notifies the VSP on every framebuffer change */
+ bool synchronous_fb;
+
+ struct notifier_block hvfb_panic_nb;
};
static uint screen_width = HVFB_WIDTH;
@@ -532,6 +537,19 @@ 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)
+{
+ struct hvfb_par *par;
+ struct fb_info *info;
+
+ par = container_of(nb, struct hvfb_par, hvfb_panic_nb);
+ par->synchronous_fb = true;
+ info = par->info;
+ synthvid_update(info);
+
+ return NOTIFY_DONE;
+}
/* Framebuffer operation handlers */
@@ -582,14 +600,44 @@ 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)
+{
+ struct hvfb_par *par = p->par;
+
+ cfb_fillrect(p, rect);
+ if (par->synchronous_fb)
+ synthvid_update(p);
+}
+
+static void hvfb_cfb_copyarea(struct fb_info *p,
+ const struct fb_copyarea *area)
+{
+ struct hvfb_par *par = p->par;
+
+ cfb_copyarea(p, area);
+ if (par->synchronous_fb)
+ synthvid_update(p);
+}
+
+static void hvfb_cfb_imageblit(struct fb_info *p,
+ const struct fb_image *image)
+{
+ struct hvfb_par *par = p->par;
+
+ cfb_imageblit(p, image);
+ if (par->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 +849,11 @@ static int hvfb_probe(struct hv_device *hdev,
par->fb_ready = true;
+ par->synchronous_fb = false;
+ par->hvfb_panic_nb.notifier_call = hvfb_on_panic;
+ atomic_notifier_chain_register(&panic_notifier_list,
+ &par->hvfb_panic_nb);
+
return 0;
error:
@@ -820,6 +873,9 @@ 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,
+ &par->hvfb_panic_nb);
+
par->update = false;
par->fb_ready = false;
--
1.9.1
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