From: "Alex Ng (LIS)" <alexng@microsoft.com>
To: Vitaly Kuznetsov <vkuznets@redhat.com>,
        "devel@linuxdriverproject.org" <devel@linuxdriverproject.org>
CC: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "KY Srinivasan" <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>
Subject: RE: [PATCH] hv: utils: properly pick TS protocol version for future
 hosts
Thread-Topic: [PATCH] hv: utils: properly pick TS protocol version for future
 hosts
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Date: Mon, 28 Nov 2016 18:16:49 +0000
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References: <20161128163027.12117-1-vkuznets@redhat.com>
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> -----Original Message-----
> From: Vitaly Kuznetsov [mailto:vkuznets@redhat.com]
> Sent: Monday, November 28, 2016 8:30 AM
> To: devel@linuxdriverproject.org
> Cc: linux-kernel@vger.kernel.org; KY Srinivasan <kys@microsoft.com>;
> Haiyang Zhang <haiyangz@microsoft.com>; Alex Ng (LIS)
> <alexng@microsoft.com>
> Subject: [PATCH] hv: utils: properly pick TS protocol version for future hosts
> 
> It is reasonable to expect that future Hyper-V versions will continue
> supporting TimeSync v4 protocol, we, however, only pick it for
> VERSION_WIN10. Currently this is not an issue as VERSION_WIN10 is the
> maximum protocol version we can negotiate but this may change in future.
> Instead of hoping that we won't forget to update it when time comes I
> suggest we change the default now.
> 

Vitaly, can you see if this upstream commit already fixes the issue you described?

https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/commit/drivers/hv?id=3da0401b4d0e17aea7526db0235d98fa535d903e

> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
> ---
>  drivers/hv/hv_util.c | 13 +++++--------
>  1 file changed, 5 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/hv/hv_util.c b/drivers/hv/hv_util.c
> index bcd0630..a13003f 100644
> --- a/drivers/hv/hv_util.c
> +++ b/drivers/hv/hv_util.c
> @@ -382,23 +382,20 @@ static int util_probe(struct hv_device *dev,
>  	 * Based on the host; initialize the framework and
>  	 * service version numbers we will negotiate.
>  	 */
> -	switch (vmbus_proto_version) {
> -	case (VERSION_WS2008):
> +	if (vmbus_proto_version <= VERSION_WS2008) {
>  		util_fw_version = UTIL_WS2K8_FW_VERSION;
>  		sd_srv_version = SD_VERSION_1;
>  		ts_srv_version = TS_VERSION_1;
>  		hb_srv_version = HB_VERSION_1;
> -		break;
> -	case(VERSION_WIN10):
> +	} else if (vmbus_proto_version < VERSION_WIN10) {
>  		util_fw_version = UTIL_FW_VERSION;
>  		sd_srv_version = SD_VERSION;
> -		ts_srv_version = TS_VERSION;
> +		ts_srv_version = TS_VERSION_3;
>  		hb_srv_version = HB_VERSION;
> -		break;
> -	default:
> +	} else {
>  		util_fw_version = UTIL_FW_VERSION;
>  		sd_srv_version = SD_VERSION;
> -		ts_srv_version = TS_VERSION_3;
> +		ts_srv_version = TS_VERSION;
>  		hb_srv_version = HB_VERSION;
>  	}
> 
> --
> 2.9.3