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Subject[PATCH v4 08/11] Input: hyperv-keyboard: Use VMBUS_RING_SIZE() for ringbuffer sizes
Date
For a Hyper-V vmbus, the size of the ringbuffer has two requirements:

1) it has to take one PAGE_SIZE for the header

2) it has to be PAGE_SIZE aligned so that double-mapping can work

VMBUS_RING_SIZE() could calculate a correct ringbuffer size which
fulfills both requirements, therefore use it to make sure vmbus work
when PAGE_SIZE != HV_HYP_PAGE_SIZE (4K).

Note that since the argument for VMBUS_RING_SIZE() is the size of
payload (data part), so it will be minus 4k (the size of header when
PAGE_SIZE = 4k) than the original value to keep the ringbuffer total
size unchanged when PAGE_SIZE = 4k.

Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Cc: Michael Kelley <mikelley@microsoft.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---
Michael and Dmitry,

I change the code because of a problem I found:

https://lore.kernel.org/lkml/20200914084600.GA45838@debian-boqun.qqnc3lrjykvubdpftowmye0fmh.lx.internal.cloudapp.net/

, so I drop your Reviewed-by or Acked-by tag. If the update version
looks good to you, may I add your tag again? Thanks in advance, and
apologies for the inconvenience.

Regards,
Boqun

drivers/input/serio/hyperv-keyboard.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/input/serio/hyperv-keyboard.c b/drivers/input/serio/hyperv-keyboard.c
index df4e9f6f4529..1a7b72a9016d 100644
--- a/drivers/input/serio/hyperv-keyboard.c
+++ b/drivers/input/serio/hyperv-keyboard.c
@@ -75,8 +75,8 @@ struct synth_kbd_keystroke {

#define HK_MAXIMUM_MESSAGE_SIZE 256

-#define KBD_VSC_SEND_RING_BUFFER_SIZE (40 * 1024)
-#define KBD_VSC_RECV_RING_BUFFER_SIZE (40 * 1024)
+#define KBD_VSC_SEND_RING_BUFFER_SIZE VMBUS_RING_SIZE(36 * 1024)
+#define KBD_VSC_RECV_RING_BUFFER_SIZE VMBUS_RING_SIZE(36 * 1024)

#define XTKBD_EMUL0 0xe0
#define XTKBD_EMUL1 0xe1
--
2.28.0
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