RE: [PATCH] scsi: storvsc: Force SPC-3 for Win8 Hosts or Later

[KY Srinivasan]

> -----Original Message-----
> From: Jeff Leung [mailto:jleung@xxxxxxxxxxxxxx]
> Sent: Monday, October 20, 2014 10:39 PM
> To: linux-scsi@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> devel@xxxxxxxxxxxxxxxxxxxxxx
> Cc: KY Srinivasan; James.Bottomley@xxxxxxxxxxxxxxxxxxxxx; Jeff Leung
> Subject: [PATCH] scsi: storvsc: Force SPC-3 for Win8 Hosts or Later
> 
> This patch forces SPC-3 for Hyper-V disks on the VMBus. As Windows 10's
> virtual SAS bus is SPC-3 compliant and there are no negative side effects on
> forcing SPC-3 compliance for Win8 hosts, this patch enables SPC-3 compliance
> by forcing it on for hosts with versions later than Win8.
> 
> Forcing SPC-3 compliance for hosts earlier than Win10 also enables TRIM
> support.
> 
> Suggested by: James Bottomley
> <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Jeff Leung <jleung@xxxxxxxxxxxxxx>
> ---
>  drivers/scsi/storvsc_drv.c |    9 +++++++++
>  1 files changed, 9 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c index
> ed0f899..afcc68e 100644
> --- a/drivers/scsi/storvsc_drv.c
> +++ b/drivers/scsi/storvsc_drv.c
> @@ -1449,6 +1449,15 @@ static int storvsc_device_configure(struct
> scsi_device *sdevice)
> 
>  	sdevice->no_write_same = 1;
> 
> +	/*
> +	 * If the host is Win2k12 or later, we pretend to be SPC-3 compliant
> +	 * and send RC16 which activates TRIM. We will only enable this on a
> +	 * host with levels greater than VERSION_WIN8
> +	 */
> +	if (vmbus_proto_version >= VERSION_WIN8) {

I would want this hack not to be in Windows 10. We can have this hack if the host is either
Ws2012 or ws2012 r2 (VERSION_WIN8 or VERSION_WIN8_1). Also this hack should apply only 
to VHD's being presented and not pass through devices.

K. Y
> +		sdevice->scsi_level = SCSI_SPC_3;
> +	}
> +
>  	return 0;
>  }
> 
> --
> 1.7.2.5

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