netdev - [PATCH v4 08/11] Input: hyperv-keyboard: Use VMBUS_RING

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Date:   Wed, 16 Sep 2020 11:48:14 +0800
From:   Boqun Feng <boqun.feng@...il.com>
To:     linux-hyperv@...r.kernel.org, linux-input@...r.kernel.org,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        linux-scsi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Cc:     "K. Y. Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Wei Liu <wei.liu@...nel.org>, Jiri Kosina <jikos@...nel.org>,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Michael Kelley <mikelley@...rosoft.com>, will@...nel.org,
        ardb@...nel.org, arnd@...db.de, catalin.marinas@....com,
        mark.rutland@....com, maz@...nel.org,
        Boqun Feng <boqun.feng@...il.com>
Subject: [PATCH v4 08/11] Input: hyperv-keyboard: Use VMBUS_RING_SIZE() for ringbuffer sizes

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@...il.com>
Cc: Michael Kelley <mikelley@...rosoft.com>
Cc: Dmitry Torokhov <dmitry.torokhov@...il.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