Re: [PATCH v4 08/11] Input: hyperv-keyboard: Use VMBUS_RING_SIZE() for ringbuffer sizes

From: Dmitry Torokhov
Date: Wed Sep 16 2020 - 00:05:22 EST

On Wed, Sep 16, 2020 at 11:48:14AM +0800, Boqun Feng wrote:
> 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
> 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@xxxxxxxxx>
> Cc: Michael Kelley <mikelley@xxxxxxxxxxxxx>
> Cc: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>

Acked-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>

Please feel free to merge through whatever tree the rest of the patches
will go.