linux-kernel - RE: [PATCH v4 10/11] Driver: hv: util: Use VMBUS_RING

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Date:   Sun, 27 Sep 2020 00:12:20 +0000
From:   Michael Kelley <mikelley@...rosoft.com>
To:     Boqun Feng <boqun.feng@...il.com>,
        "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
        "linux-input@...r.kernel.org" <linux-input@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
CC:     KY 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>,
        "will@...nel.org" <will@...nel.org>,
        "ardb@...nel.org" <ardb@...nel.org>,
        "arnd@...db.de" <arnd@...db.de>,
        "catalin.marinas@....com" <catalin.marinas@....com>,
        "Mark.Rutland@....com" <Mark.Rutland@....com>,
        "maz@...nel.org" <maz@...nel.org>
Subject: RE: [PATCH v4 10/11] Driver: hv: util: Use VMBUS_RING_SIZE() for
 ringbuffer sizes

From: Boqun Feng <boqun.feng@...il.com> Sent: Tuesday, September 15, 2020 8:48 PM
> 
> 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>
> 
> ---
> Michael,
> 
> I drop your Reviewed-by tag because of the page align issue. Could you
> review this updated version? Thanks!
> 
> Regards,
> Boqun
> 
> 
>  drivers/hv/hv_util.c | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/hv/hv_util.c b/drivers/hv/hv_util.c
> index a4e8d96513c2..05566ecdbe4b 100644
> --- a/drivers/hv/hv_util.c
> +++ b/drivers/hv/hv_util.c
> @@ -500,6 +500,9 @@ static void heartbeat_onchannelcallback(void *context)
>  	}
>  }
> 
> +#define HV_UTIL_RING_SEND_SIZE VMBUS_RING_SIZE(3 * HV_HYP_PAGE_SIZE)
> +#define HV_UTIL_RING_RECV_SIZE VMBUS_RING_SIZE(3 * HV_HYP_PAGE_SIZE)
> +
>  static int util_probe(struct hv_device *dev,
>  			const struct hv_vmbus_device_id *dev_id)
>  {
> @@ -530,8 +533,8 @@ static int util_probe(struct hv_device *dev,
> 
>  	hv_set_drvdata(dev, srv);
> 
> -	ret = vmbus_open(dev->channel, 4 * HV_HYP_PAGE_SIZE,
> -			 4 * HV_HYP_PAGE_SIZE, NULL, 0, srv->util_cb,
> +	ret = vmbus_open(dev->channel, HV_UTIL_RING_SEND_SIZE,
> +			 HV_UTIL_RING_RECV_SIZE, NULL, 0, srv->util_cb,
>  			 dev->channel);
>  	if (ret)
>  		goto error;
> @@ -590,8 +593,8 @@ static int util_resume(struct hv_device *dev)
>  			return ret;
>  	}
> 
> -	ret = vmbus_open(dev->channel, 4 * HV_HYP_PAGE_SIZE,
> -			 4 * HV_HYP_PAGE_SIZE, NULL, 0, srv->util_cb,
> +	ret = vmbus_open(dev->channel, HV_UTIL_RING_SEND_SIZE,
> +			 HV_UTIL_RING_RECV_SIZE, NULL, 0, srv->util_cb,
>  			 dev->channel);
>  	return ret;
>  }
> --
> 2.28.0

Reviewed-by:  Michael Kelley <mikelley@...rosoft.com>