Hyper-V SSD passthrough fix backport

Hyper-V SSD passthrough fix backport

[Sitsofe Wheeler]

I'd like to nominate f1c635b439a5c01776fe3a25b1e2dc546ea82e6f
(https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/scsi/storvsc_drv.c?id=f1c635b439a5c01776fe3a25b1e2dc546ea82e6f
) to be backported to 4.4 stable because it looks like without it
passthrough SSD disks won't work and will generate faux devices. It is
also being carried by Ubuntu:
http://kernel.ubuntu.com/git/ubuntu/ubuntu-xenial.git/log/drivers/scsi/storvsc_drv.c?h=Ubuntu-4.4.0-98.121
along with other Hyper-V patches in their 4.4 tree.

I'm not 100% sure that this one will fix what is being seen but I'm
coming to this conclusion based on
https://bugs.launchpad.net/ubuntu/xenial/+source/linux/+bug/1679898/comments/144
.

-- 
Sitsofe | http://sucs.org/~sits/

Re: Hyper-V SSD passthrough fix backport

[Greg KH]

On Tue, Nov 28, 2017 at 10:58:25PM +0000, Sitsofe Wheeler wrote:
> I'd like to nominate f1c635b439a5c01776fe3a25b1e2dc546ea82e6f
> (https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/scsi/storvsc_drv.c?id=f1c635b439a5c01776fe3a25b1e2dc546ea82e6f
> ) to be backported to 4.4 stable because it looks like without it
> passthrough SSD disks won't work and will generate faux devices. It is
> also being carried by Ubuntu:
> http://kernel.ubuntu.com/git/ubuntu/ubuntu-xenial.git/log/drivers/scsi/storvsc_drv.c?h=Ubuntu-4.4.0-98.121
> along with other Hyper-V patches in their 4.4 tree.
> 
> I'm not 100% sure that this one will fix what is being seen but I'm
> coming to this conclusion based on
> https://bugs.launchpad.net/ubuntu/xenial/+source/linux/+bug/1679898/comments/144

Can you test it to determine if this really does what you think it does
to solve the problem?  The changelog text makes it seem not necessary at
all.

thanks,

greg k-h

Re: Hyper-V SSD passthrough fix backport

[Sitsofe Wheeler]

[-- Attachment #1: Type: text/plain, Size: 1507 bytes --]

On 29 November 2017 at 08:06, Greg KH <greg@kroah.com> wrote:
> On Tue, Nov 28, 2017 at 10:58:25PM +0000, Sitsofe Wheeler wrote:
>> I'd like to nominate f1c635b439a5c01776fe3a25b1e2dc546ea82e6f
>> (https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/scsi/storvsc_drv.c?id=f1c635b439a5c01776fe3a25b1e2dc546ea82e6f
>> ) to be backported to 4.4 stable because it looks like without it
>> passthrough SSD disks won't work and will generate faux devices. It is
>> also being carried by Ubuntu:
>> http://kernel.ubuntu.com/git/ubuntu/ubuntu-xenial.git/log/drivers/scsi/storvsc_drv.c?h=Ubuntu-4.4.0-98.121
>> along with other Hyper-V patches in their 4.4 tree.
>>
>> I'm not 100% sure that this one will fix what is being seen but I'm
>> coming to this conclusion based on
>> https://bugs.launchpad.net/ubuntu/xenial/+source/linux/+bug/1679898/comments/144
>
> Can you test it to determine if this really does what you think it does
> to solve the problem?  The changelog text makes it seem not necessary at
> all.

I agree the changelog makes it seem totally unnecessary but the
changelog is wrong in this case :-) I have checked out 4.4.102 and
built it, run it and hit the error. When applying the patch attached
(which is basically f1c635b439a5c01776fe3a25b1e2dc546ea82e6f with the
lines removing static int msft_blist_flags = BLIST_TRY_VPD_PAGES;
moved about) and the problem was resolved.

I'm happy for others to weigh on what I'm seeing.

-- 
Sitsofe | http://sucs.org/~sits/

[-- Attachment #2: hv.patch --]
[-- Type: application/octet-stream, Size: 2061 bytes --]

diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
index 6df2841..5e4e1ba 100644
--- a/drivers/scsi/storvsc_drv.c
+++ b/drivers/scsi/storvsc_drv.c
@@ -379,8 +379,6 @@ MODULE_PARM_DESC(vcpus_per_sub_channel, "Ratio of VCPUs to subchannels");
  */
 static int storvsc_timeout = 180;
 
-static int msft_blist_flags = BLIST_TRY_VPD_PAGES;
-
 
 static void storvsc_on_channel_callback(void *context);
 
@@ -1241,6 +1239,22 @@ static int storvsc_do_io(struct hv_device *device,
 	return ret;
 }
 
+static int storvsc_device_alloc(struct scsi_device *sdevice)
+{
+	/*
+	 * Set blist flag to permit the reading of the VPD pages even when
+	 * the target may claim SPC-2 compliance. MSFT targets currently
+	 * claim SPC-2 compliance while they implement post SPC-2 features.
+	 * With this flag we can correctly handle WRITE_SAME_16 issues.
+	 *
+	 * Hypervisor reports SCSI_UNKNOWN type for DVD ROM device but
+	 * still supports REPORT LUN.
+	 */
+	sdevice->sdev_bflags = BLIST_REPORTLUN2 | BLIST_TRY_VPD_PAGES;
+
+	return 0;
+}
+
 static int storvsc_device_configure(struct scsi_device *sdevice)
 {
 
@@ -1256,14 +1270,6 @@ static int storvsc_device_configure(struct scsi_device *sdevice)
 	sdevice->no_write_same = 1;
 
 	/*
-	 * Add blist flags to permit the reading of the VPD pages even when
-	 * the target may claim SPC-2 compliance. MSFT targets currently
-	 * claim SPC-2 compliance while they implement post SPC-2 features.
-	 * With this patch we can correctly handle WRITE_SAME_16 issues.
-	 */
-	sdevice->sdev_bflags |= msft_blist_flags;
-
-	/*
 	 * If the host is WIN8 or WIN8 R2, claim conformance to SPC-3
 	 * if the device is a MSFT virtual device.  If the host is
 	 * WIN10 or newer, allow write_same.
@@ -1529,6 +1535,7 @@ static struct scsi_host_template scsi_driver = {
 	.eh_host_reset_handler =	storvsc_host_reset_handler,
 	.proc_name =		"storvsc_host",
 	.eh_timed_out =		storvsc_eh_timed_out,
+	.slave_alloc =		storvsc_device_alloc,
 	.slave_configure =	storvsc_device_configure,
 	.cmd_per_lun =		255,
 	.this_id =		-1,

Re: Hyper-V SSD passthrough fix backport

[Sitsofe Wheeler]

On 29 November 2017 at 08:11, Sitsofe Wheeler <sitsofe@gmail.com> wrote:
> On 29 November 2017 at 08:06, Greg KH <greg@kroah.com> wrote:
>> On Tue, Nov 28, 2017 at 10:58:25PM +0000, Sitsofe Wheeler wrote:
>>> I'd like to nominate f1c635b439a5c01776fe3a25b1e2dc546ea82e6f
>>> (https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/scsi/storvsc_drv.c?id=f1c635b439a5c01776fe3a25b1e2dc546ea82e6f
>>> ) to be backported to 4.4 stable because it looks like without it
>>> passthrough SSD disks won't work and will generate faux devices. It is
>>> also being carried by Ubuntu:
>>> http://kernel.ubuntu.com/git/ubuntu/ubuntu-xenial.git/log/drivers/scsi/storvsc_drv.c?h=Ubuntu-4.4.0-98.121
>>> along with other Hyper-V patches in their 4.4 tree.
>>>
>>> I'm not 100% sure that this one will fix what is being seen but I'm
>>> coming to this conclusion based on
>>> https://bugs.launchpad.net/ubuntu/xenial/+source/linux/+bug/1679898/comments/144
>>
>> Can you test it to determine if this really does what you think it does
>> to solve the problem?  The changelog text makes it seem not necessary at
>> all.
>
> I agree the changelog makes it seem totally unnecessary but the
> changelog is wrong in this case :-) I have checked out 4.4.102 and
> built it, run it and hit the error. When applying the patch attached
> (which is basically f1c635b439a5c01776fe3a25b1e2dc546ea82e6f with the
> lines removing static int msft_blist_flags = BLIST_TRY_VPD_PAGES;
> moved about) and the problem was resolved.
>
> I'm happy for others to weigh on what I'm seeing.

I will also note that this patch was deemed necessary/suitable for
backporting to 4.9 and 4.10 back in May -
(https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/log/drivers/scsi/storvsc_drv.c?h=linux-4.9.y
and https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/log/drivers/scsi/storvsc_drv.c?h=linux-4.10.y
). Looking at https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/log/drivers/scsi/storvsc_drv.c?h=linux-4.1.y
perhaps this is also suitable for 4.1 stable too (but I haven't tested
4.1, only 4.4.102)...

-- 
Sitsofe | http://sucs.org/~sits/

Re: Hyper-V SSD passthrough fix backport

[Sitsofe Wheeler]

On 29 November 2017 at 10:40, Sitsofe Wheeler <sitsofe@gmail.com> wrote:
> On 29 November 2017 at 08:11, Sitsofe Wheeler <sitsofe@gmail.com> wrote:
>> On 29 November 2017 at 08:06, Greg KH <greg@kroah.com> wrote:
>>> On Tue, Nov 28, 2017 at 10:58:25PM +0000, Sitsofe Wheeler wrote:
>>>> I'd like to nominate f1c635b439a5c01776fe3a25b1e2dc546ea82e6f
>>>> (https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/scsi/storvsc_drv.c?id=f1c635b439a5c01776fe3a25b1e2dc546ea82e6f
>>>> ) to be backported to 4.4 stable because it looks like without it
>>>> passthrough SSD disks won't work and will generate faux devices. It is
>>>> also being carried by Ubuntu:
>>>> http://kernel.ubuntu.com/git/ubuntu/ubuntu-xenial.git/log/drivers/scsi/storvsc_drv.c?h=Ubuntu-4.4.0-98.121
>>>> along with other Hyper-V patches in their 4.4 tree.
>>>>
>>>> I'm not 100% sure that this one will fix what is being seen but I'm
>>>> coming to this conclusion based on
>>>> https://bugs.launchpad.net/ubuntu/xenial/+source/linux/+bug/1679898/comments/144
>>>
>>> Can you test it to determine if this really does what you think it does
>>> to solve the problem?  The changelog text makes it seem not necessary at
>>> all.
>>
>> I agree the changelog makes it seem totally unnecessary but the
>> changelog is wrong in this case :-) I have checked out 4.4.102 and
>> built it, run it and hit the error. When applying the patch attached
>> (which is basically f1c635b439a5c01776fe3a25b1e2dc546ea82e6f with the
>> lines removing static int msft_blist_flags = BLIST_TRY_VPD_PAGES;
>> moved about) and the problem was resolved.
>>
>> I'm happy for others to weigh on what I'm seeing.
>
> I will also note that this patch was deemed necessary/suitable for
> backporting to 4.9 and 4.10 back in May -
> (https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/log/drivers/scsi/storvsc_drv.c?h=linux-4.9.y
> and https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/log/drivers/scsi/storvsc_drv.c?h=linux-4.10.y
> ). Looking at https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/log/drivers/scsi/storvsc_drv.c?h=linux-4.1.y
> perhaps this is also suitable for 4.1 stable too (but I haven't tested
> 4.1, only 4.4.102)...

One more data point - back in May
(https://www.spinics.net/lists/stable/msg170046.html ) you noted this
in relation to one of the stable patch requests for this:
"it's interesting how you deleted the changelog
comments here saying this was only needed for 4.11 and no older kernels
:)"

and there's a follow up reply
(https://www.spinics.net/lists/stable/msg170125.html ) where Stephen
says:

"At the time I only had reports of problem with 4.11.
But others ran into issue with 4.10 and 4.9"

-- 
Sitsofe | http://sucs.org/~sits/

Re: Hyper-V SSD passthrough fix backport

[Stephen Hemminger]

On Wed, 29 Nov 2017 12:09:03 +0000
Sitsofe Wheeler <sitsofe@gmail.com> wrote:

> On 29 November 2017 at 10:40, Sitsofe Wheeler <sitsofe@gmail.com> wrote:
> > On 29 November 2017 at 08:11, Sitsofe Wheeler <sitsofe@gmail.com> wrote:  
> >> On 29 November 2017 at 08:06, Greg KH <greg@kroah.com> wrote:  
> >>> On Tue, Nov 28, 2017 at 10:58:25PM +0000, Sitsofe Wheeler wrote:  
> >>>> I'd like to nominate f1c635b439a5c01776fe3a25b1e2dc546ea82e6f
> >>>> (https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/scsi/storvsc_drv.c?id=f1c635b439a5c01776fe3a25b1e2dc546ea82e6f
> >>>> ) to be backported to 4.4 stable because it looks like without it
> >>>> passthrough SSD disks won't work and will generate faux devices. It is
> >>>> also being carried by Ubuntu:
> >>>> http://kernel.ubuntu.com/git/ubuntu/ubuntu-xenial.git/log/drivers/scsi/storvsc_drv.c?h=Ubuntu-4.4.0-98.121
> >>>> along with other Hyper-V patches in their 4.4 tree.
> >>>>
> >>>> I'm not 100% sure that this one will fix what is being seen but I'm
> >>>> coming to this conclusion based on
> >>>> https://bugs.launchpad.net/ubuntu/xenial/+source/linux/+bug/1679898/comments/144  
> >>>
> >>> Can you test it to determine if this really does what you think it does
> >>> to solve the problem?  The changelog text makes it seem not necessary at
> >>> all.  
> >>
> >> I agree the changelog makes it seem totally unnecessary but the
> >> changelog is wrong in this case :-) I have checked out 4.4.102 and
> >> built it, run it and hit the error. When applying the patch attached
> >> (which is basically f1c635b439a5c01776fe3a25b1e2dc546ea82e6f with the
> >> lines removing static int msft_blist_flags = BLIST_TRY_VPD_PAGES;
> >> moved about) and the problem was resolved.
> >>
> >> I'm happy for others to weigh on what I'm seeing.  
> >
> > I will also note that this patch was deemed necessary/suitable for
> > backporting to 4.9 and 4.10 back in May -
> > (https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/log/drivers/scsi/storvsc_drv.c?h=linux-4.9.y
> > and https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/log/drivers/scsi/storvsc_drv.c?h=linux-4.10.y
> > ). Looking at https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/log/drivers/scsi/storvsc_drv.c?h=linux-4.1.y
> > perhaps this is also suitable for 4.1 stable too (but I haven't tested
> > 4.1, only 4.4.102)...  
> 
> One more data point - back in May
> (https://www.spinics.net/lists/stable/msg170046.html ) you noted this
> in relation to one of the stable patch requests for this:
> "it's interesting how you deleted the changelog
> comments here saying this was only needed for 4.11 and no older kernels
> :)"
> 
> and there's a follow up reply
> (https://www.spinics.net/lists/stable/msg170125.html ) where Stephen
> says:
> 
> "At the time I only had reports of problem with 4.11.
> But others ran into issue with 4.10 and 4.9"

The changelog was about where the problem was seen. It makes sense
that this also occurs with other classes of storage devices;
hadn't tried all the possible configurations.

Re: Hyper-V SSD passthrough fix backport

[Greg KH]

On Wed, Nov 29, 2017 at 03:21:08PM -0800, Stephen Hemminger wrote:
> On Wed, 29 Nov 2017 12:09:03 +0000
> Sitsofe Wheeler <sitsofe@gmail.com> wrote:
> 
> > On 29 November 2017 at 10:40, Sitsofe Wheeler <sitsofe@gmail.com> wrote:
> > > On 29 November 2017 at 08:11, Sitsofe Wheeler <sitsofe@gmail.com> wrote:  
> > >> On 29 November 2017 at 08:06, Greg KH <greg@kroah.com> wrote:  
> > >>> On Tue, Nov 28, 2017 at 10:58:25PM +0000, Sitsofe Wheeler wrote:  
> > >>>> I'd like to nominate f1c635b439a5c01776fe3a25b1e2dc546ea82e6f
> > >>>> (https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/scsi/storvsc_drv.c?id=f1c635b439a5c01776fe3a25b1e2dc546ea82e6f
> > >>>> ) to be backported to 4.4 stable because it looks like without it
> > >>>> passthrough SSD disks won't work and will generate faux devices. It is
> > >>>> also being carried by Ubuntu:
> > >>>> http://kernel.ubuntu.com/git/ubuntu/ubuntu-xenial.git/log/drivers/scsi/storvsc_drv.c?h=Ubuntu-4.4.0-98.121
> > >>>> along with other Hyper-V patches in their 4.4 tree.
> > >>>>
> > >>>> I'm not 100% sure that this one will fix what is being seen but I'm
> > >>>> coming to this conclusion based on
> > >>>> https://bugs.launchpad.net/ubuntu/xenial/+source/linux/+bug/1679898/comments/144  
> > >>>
> > >>> Can you test it to determine if this really does what you think it does
> > >>> to solve the problem?  The changelog text makes it seem not necessary at
> > >>> all.  
> > >>
> > >> I agree the changelog makes it seem totally unnecessary but the
> > >> changelog is wrong in this case :-) I have checked out 4.4.102 and
> > >> built it, run it and hit the error. When applying the patch attached
> > >> (which is basically f1c635b439a5c01776fe3a25b1e2dc546ea82e6f with the
> > >> lines removing static int msft_blist_flags = BLIST_TRY_VPD_PAGES;
> > >> moved about) and the problem was resolved.
> > >>
> > >> I'm happy for others to weigh on what I'm seeing.  
> > >
> > > I will also note that this patch was deemed necessary/suitable for
> > > backporting to 4.9 and 4.10 back in May -
> > > (https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/log/drivers/scsi/storvsc_drv.c?h=linux-4.9.y
> > > and https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/log/drivers/scsi/storvsc_drv.c?h=linux-4.10.y
> > > ). Looking at https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/log/drivers/scsi/storvsc_drv.c?h=linux-4.1.y
> > > perhaps this is also suitable for 4.1 stable too (but I haven't tested
> > > 4.1, only 4.4.102)...  
> > 
> > One more data point - back in May
> > (https://www.spinics.net/lists/stable/msg170046.html ) you noted this
> > in relation to one of the stable patch requests for this:
> > "it's interesting how you deleted the changelog
> > comments here saying this was only needed for 4.11 and no older kernels
> > :)"
> > 
> > and there's a follow up reply
> > (https://www.spinics.net/lists/stable/msg170125.html ) where Stephen
> > says:
> > 
> > "At the time I only had reports of problem with 4.11.
> > But others ran into issue with 4.10 and 4.9"
> 
> The changelog was about where the problem was seen. It makes sense
> that this also occurs with other classes of storage devices;
> hadn't tried all the possible configurations.

So, what does the maintainer of the driver recommend here?  Should I
backport this patch, or not?

thanks,

greg k-h

Re: Hyper-V SSD passthrough fix backport

[Sitsofe Wheeler]

(Forwarding to all Hyper-V maintainers due to lack of response to
Greg's question.

There's something about this patch which makes it keep falling through
the cracks: in March when someone asked for this patch to be
backported (http://lkml.iu.edu/hypermail/linux/kernel/1703.3/03056.html
) no one confirmed it should so Greg wound up dropping it
(http://lkml.iu.edu/hypermail/linux/kernel/1703.3/04774.html ). Given
this, can I urge people not to overlook this latest query...)

---------- Forwarded message ----------
From: Greg KH <greg@kroah.com>
Date: 4 December 2017 at 12:10
Subject: Re: Hyper-V SSD passthrough fix backport
To: Stephen Hemminger <stephen@networkplumber.org>
Cc: Sitsofe Wheeler <sitsofe@gmail.com>, stable
<stable@vger.kernel.org>, "Martin K. Petersen"
<martin.petersen@oracle.com>


On Wed, Nov 29, 2017 at 03:21:08PM -0800, Stephen Hemminger wrote:
> On Wed, 29 Nov 2017 12:09:03 +0000
> Sitsofe Wheeler <sitsofe@gmail.com> wrote:
>
> > On 29 November 2017 at 10:40, Sitsofe Wheeler <sitsofe@gmail.com> wrote:
> > > On 29 November 2017 at 08:11, Sitsofe Wheeler <sitsofe@gmail.com> wrote:
> > >> On 29 November 2017 at 08:06, Greg KH <greg@kroah.com> wrote:
> > >>> On Tue, Nov 28, 2017 at 10:58:25PM +0000, Sitsofe Wheeler wrote:
> > >>>> I'd like to nominate f1c635b439a5c01776fe3a25b1e2dc546ea82e6f
> > >>>> (https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/scsi/storvsc_drv.c?id=f1c635b439a5c01776fe3a25b1e2dc546ea82e6f
> > >>>> ) to be backported to 4.4 stable because it looks like without it
> > >>>> passthrough SSD disks won't work and will generate faux devices. It is
> > >>>> also being carried by Ubuntu:
> > >>>> http://kernel.ubuntu.com/git/ubuntu/ubuntu-xenial.git/log/drivers/scsi/storvsc_drv.c?h=Ubuntu-4.4.0-98.121
> > >>>> along with other Hyper-V patches in their 4.4 tree.
> > >>>>
> > >>>> I'm not 100% sure that this one will fix what is being seen but I'm
> > >>>> coming to this conclusion based on
> > >>>> https://bugs.launchpad.net/ubuntu/xenial/+source/linux/+bug/1679898/comments/144
> > >>>
> > >>> Can you test it to determine if this really does what you think it does
> > >>> to solve the problem?  The changelog text makes it seem not necessary at
> > >>> all.
> > >>
> > >> I agree the changelog makes it seem totally unnecessary but the
> > >> changelog is wrong in this case :-) I have checked out 4.4.102 and
> > >> built it, run it and hit the error. When applying the patch attached
> > >> (which is basically f1c635b439a5c01776fe3a25b1e2dc546ea82e6f with the
> > >> lines removing static int msft_blist_flags = BLIST_TRY_VPD_PAGES;
> > >> moved about) and the problem was resolved.
> > >>
> > >> I'm happy for others to weigh on what I'm seeing.
> > >
> > > I will also note that this patch was deemed necessary/suitable for
> > > backporting to 4.9 and 4.10 back in May -
> > > (https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/log/drivers/scsi/storvsc_drv.c?h=linux-4.9.y
> > > and https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/log/drivers/scsi/storvsc_drv.c?h=linux-4.10.y
> > > ). Looking at https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/log/drivers/scsi/storvsc_drv.c?h=linux-4.1.y
> > > perhaps this is also suitable for 4.1 stable too (but I haven't tested
> > > 4.1, only 4.4.102)...
> >
> > One more data point - back in May
> > (https://www.spinics.net/lists/stable/msg170046.html ) you noted this
> > in relation to one of the stable patch requests for this:
> > "it's interesting how you deleted the changelog
> > comments here saying this was only needed for 4.11 and no older kernels
> > :)"
> >
> > and there's a follow up reply
> > (https://www.spinics.net/lists/stable/msg170125.html ) where Stephen
> > says:
> >
> > "At the time I only had reports of problem with 4.11.
> > But others ran into issue with 4.10 and 4.9"
>
> The changelog was about where the problem was seen. It makes sense
> that this also occurs with other classes of storage devices;
> hadn't tried all the possible configurations.

So, what does the maintainer of the driver recommend here?  Should I
backport this patch, or not?

thanks,

greg k-h

-- 
Sitsofe | http://sucs.org/~sits/

RE: Hyper-V SSD passthrough fix backport

[Haiyang Zhang]

> -----Original Message-----
> From: Sitsofe Wheeler [mailto:sitsofe@gmail.com]
> Sent: Thursday, December 7, 2017 2:11 AM
> To: KY Srinivasan <kys@microsoft.com>; Haiyang Zhang
> <haiyangz@microsoft.com>; Stephen Hemminger
> <stephen@networkplumber.org>
> Cc: Greg KH <greg@kroah.com>; stable <stable@vger.kernel.org>; Martin K.
> Petersen <martin.petersen@oracle.com>; Joseph Salisbury
> <joseph.salisbury@canonical.com>
> Subject: Re: Hyper-V SSD passthrough fix backport
> 
> (Forwarding to all Hyper-V maintainers due to lack of response to Greg's
> question.
> 
> There's something about this patch which makes it keep falling through the
> cracks: in March when someone asked for this patch to be backported
> (https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Flkml.iu
> .edu%2Fhypermail%2Flinux%2Fkernel%2F1703.3%2F03056.html&data=02%7
> C01%7Chaiyangz%40microsoft.com%7C6a76d2287beb410964b408d53d41b50
> 6%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C63648227478790207
> 0&sdata=WclICMSv55hCVH6maLH4LWlp8f7xau1UQ9Ffuy1u15U%3D&reserve
> d=0
> ) no one confirmed it should so Greg wound up dropping it
> (https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Flkml.iu
> .edu%2Fhypermail%2Flinux%2Fkernel%2F1703.3%2F04774.html&data=02%7
> C01%7Chaiyangz%40microsoft.com%7C6a76d2287beb410964b408d53d41b50
> 6%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C63648227478790207
> 0&sdata=78fMkbPXzWhn8X5x0EdjXqbpzQAEqS3TiXxVmKe1csQ%3D&reserv
> ed=0 ). Given this, can I urge people not to overlook this latest query...)
> 

KY, 
Maybe it needs to be put onto your queue?

Thanks,
- Haiyang

Re: Hyper-V SSD passthrough fix backport

[Stephen Hemminger]

On Thu, 7 Dec 2017 07:10:45 +0000
Sitsofe Wheeler <sitsofe@gmail.com> wrote:

> (Forwarding to all Hyper-V maintainers due to lack of response to
> Greg's question.
> 
> There's something about this patch which makes it keep falling through
> the cracks: in March when someone asked for this patch to be
> backported (http://lkml.iu.edu/hypermail/linux/kernel/1703.3/03056.html
> ) no one confirmed it should so Greg wound up dropping it
> (http://lkml.iu.edu/hypermail/linux/kernel/1703.3/04774.html ). Given
> this, can I urge people not to overlook this latest query...)
> 
> ---------- Forwarded message ----------
> From: Greg KH <greg@kroah.com>
> Date: 4 December 2017 at 12:10
> Subject: Re: Hyper-V SSD passthrough fix backport
> To: Stephen Hemminger <stephen@networkplumber.org>
> Cc: Sitsofe Wheeler <sitsofe@gmail.com>, stable
> <stable@vger.kernel.org>, "Martin K. Petersen"
> <martin.petersen@oracle.com>
> 
> 
> On Wed, Nov 29, 2017 at 03:21:08PM -0800, Stephen Hemminger wrote:
> > On Wed, 29 Nov 2017 12:09:03 +0000
> > Sitsofe Wheeler <sitsofe@gmail.com> wrote:
> >  
> > > On 29 November 2017 at 10:40, Sitsofe Wheeler <sitsofe@gmail.com> wrote:  
> > > > On 29 November 2017 at 08:11, Sitsofe Wheeler <sitsofe@gmail.com> wrote:  
> > > >> On 29 November 2017 at 08:06, Greg KH <greg@kroah.com> wrote:  
> > > >>> On Tue, Nov 28, 2017 at 10:58:25PM +0000, Sitsofe Wheeler wrote:  
> > > >>>> I'd like to nominate f1c635b439a5c01776fe3a25b1e2dc546ea82e6f
> > > >>>> (https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/scsi/storvsc_drv.c?id=f1c635b439a5c01776fe3a25b1e2dc546ea82e6f
> > > >>>> ) to be backported to 4.4 stable because it looks like without it
> > > >>>> passthrough SSD disks won't work and will generate faux devices. It is
> > > >>>> also being carried by Ubuntu:
> > > >>>> http://kernel.ubuntu.com/git/ubuntu/ubuntu-xenial.git/log/drivers/scsi/storvsc_drv.c?h=Ubuntu-4.4.0-98.121
> > > >>>> along with other Hyper-V patches in their 4.4 tree.
> > > >>>>
> > > >>>> I'm not 100% sure that this one will fix what is being seen but I'm
> > > >>>> coming to this conclusion based on
> > > >>>> https://bugs.launchpad.net/ubuntu/xenial/+source/linux/+bug/1679898/comments/144  
> > > >>>
> > > >>> Can you test it to determine if this really does what you think it does
> > > >>> to solve the problem?  The changelog text makes it seem not necessary at
> > > >>> all.  
> > > >>
> > > >> I agree the changelog makes it seem totally unnecessary but the
> > > >> changelog is wrong in this case :-) I have checked out 4.4.102 and
> > > >> built it, run it and hit the error. When applying the patch attached
> > > >> (which is basically f1c635b439a5c01776fe3a25b1e2dc546ea82e6f with the
> > > >> lines removing static int msft_blist_flags = BLIST_TRY_VPD_PAGES;
> > > >> moved about) and the problem was resolved.
> > > >>
> > > >> I'm happy for others to weigh on what I'm seeing.  
> > > >
> > > > I will also note that this patch was deemed necessary/suitable for
> > > > backporting to 4.9 and 4.10 back in May -
> > > > (https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/log/drivers/scsi/storvsc_drv.c?h=linux-4.9.y
> > > > and https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/log/drivers/scsi/storvsc_drv.c?h=linux-4.10.y
> > > > ). Looking at https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/log/drivers/scsi/storvsc_drv.c?h=linux-4.1.y
> > > > perhaps this is also suitable for 4.1 stable too (but I haven't tested
> > > > 4.1, only 4.4.102)...  
> > >
> > > One more data point - back in May
> > > (https://www.spinics.net/lists/stable/msg170046.html ) you noted this
> > > in relation to one of the stable patch requests for this:
> > > "it's interesting how you deleted the changelog
> > > comments here saying this was only needed for 4.11 and no older kernels
> > > :)"
> > >
> > > and there's a follow up reply
> > > (https://www.spinics.net/lists/stable/msg170125.html ) where Stephen
> > > says:
> > >
> > > "At the time I only had reports of problem with 4.11.
> > > But others ran into issue with 4.10 and 4.9"  
> >
> > The changelog was about where the problem was seen. It makes sense
> > that this also occurs with other classes of storage devices;
> > hadn't tried all the possible configurations.  
> 
> So, what does the maintainer of the driver recommend here?  Should I
> backport this patch, or not?
> 
> thanks,
> 
> greg k-h
> 

I was waiting for some feedback from Dexuan who has done most of the recent work on
Hyper-V storage. His feedback is.

> Hi Stephen,
> My understanding is that the patch was made to work around a host emulation
> defect of SCSI DVD device, so old kernels should also need this patch, but I didn't
> know it could fix SSD passthrough, and actually I was not aware of any bug 
> related to SSD passthrough.
> 
> Thanks,
> -- Dexuan

So yes, I think the backport is appropriate. The SSD fix is an added beneficial
side effect.

Re: Hyper-V SSD passthrough fix backport

[Greg KH]

On Fri, Dec 08, 2017 at 10:12:15AM -0800, Stephen Hemminger wrote:
> On Thu, 7 Dec 2017 07:10:45 +0000
> Sitsofe Wheeler <sitsofe@gmail.com> wrote:
> 
> > (Forwarding to all Hyper-V maintainers due to lack of response to
> > Greg's question.
> > 
> > There's something about this patch which makes it keep falling through
> > the cracks: in March when someone asked for this patch to be
> > backported (http://lkml.iu.edu/hypermail/linux/kernel/1703.3/03056.html
> > ) no one confirmed it should so Greg wound up dropping it
> > (http://lkml.iu.edu/hypermail/linux/kernel/1703.3/04774.html ). Given
> > this, can I urge people not to overlook this latest query...)
> > 
> > ---------- Forwarded message ----------
> > From: Greg KH <greg@kroah.com>
> > Date: 4 December 2017 at 12:10
> > Subject: Re: Hyper-V SSD passthrough fix backport
> > To: Stephen Hemminger <stephen@networkplumber.org>
> > Cc: Sitsofe Wheeler <sitsofe@gmail.com>, stable
> > <stable@vger.kernel.org>, "Martin K. Petersen"
> > <martin.petersen@oracle.com>
> > 
> > 
> > On Wed, Nov 29, 2017 at 03:21:08PM -0800, Stephen Hemminger wrote:
> > > On Wed, 29 Nov 2017 12:09:03 +0000
> > > Sitsofe Wheeler <sitsofe@gmail.com> wrote:
> > >  
> > > > On 29 November 2017 at 10:40, Sitsofe Wheeler <sitsofe@gmail.com> wrote:  
> > > > > On 29 November 2017 at 08:11, Sitsofe Wheeler <sitsofe@gmail.com> wrote:  
> > > > >> On 29 November 2017 at 08:06, Greg KH <greg@kroah.com> wrote:  
> > > > >>> On Tue, Nov 28, 2017 at 10:58:25PM +0000, Sitsofe Wheeler wrote:  
> > > > >>>> I'd like to nominate f1c635b439a5c01776fe3a25b1e2dc546ea82e6f
> > > > >>>> (https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/scsi/storvsc_drv.c?id=f1c635b439a5c01776fe3a25b1e2dc546ea82e6f
> > > > >>>> ) to be backported to 4.4 stable because it looks like without it
> > > > >>>> passthrough SSD disks won't work and will generate faux devices. It is
> > > > >>>> also being carried by Ubuntu:
> > > > >>>> http://kernel.ubuntu.com/git/ubuntu/ubuntu-xenial.git/log/drivers/scsi/storvsc_drv.c?h=Ubuntu-4.4.0-98.121
> > > > >>>> along with other Hyper-V patches in their 4.4 tree.
> > > > >>>>
> > > > >>>> I'm not 100% sure that this one will fix what is being seen but I'm
> > > > >>>> coming to this conclusion based on
> > > > >>>> https://bugs.launchpad.net/ubuntu/xenial/+source/linux/+bug/1679898/comments/144  
> > > > >>>
> > > > >>> Can you test it to determine if this really does what you think it does
> > > > >>> to solve the problem?  The changelog text makes it seem not necessary at
> > > > >>> all.  
> > > > >>
> > > > >> I agree the changelog makes it seem totally unnecessary but the
> > > > >> changelog is wrong in this case :-) I have checked out 4.4.102 and
> > > > >> built it, run it and hit the error. When applying the patch attached
> > > > >> (which is basically f1c635b439a5c01776fe3a25b1e2dc546ea82e6f with the
> > > > >> lines removing static int msft_blist_flags = BLIST_TRY_VPD_PAGES;
> > > > >> moved about) and the problem was resolved.
> > > > >>
> > > > >> I'm happy for others to weigh on what I'm seeing.  
> > > > >
> > > > > I will also note that this patch was deemed necessary/suitable for
> > > > > backporting to 4.9 and 4.10 back in May -
> > > > > (https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/log/drivers/scsi/storvsc_drv.c?h=linux-4.9.y
> > > > > and https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/log/drivers/scsi/storvsc_drv.c?h=linux-4.10.y
> > > > > ). Looking at https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/log/drivers/scsi/storvsc_drv.c?h=linux-4.1.y
> > > > > perhaps this is also suitable for 4.1 stable too (but I haven't tested
> > > > > 4.1, only 4.4.102)...  
> > > >
> > > > One more data point - back in May
> > > > (https://www.spinics.net/lists/stable/msg170046.html ) you noted this
> > > > in relation to one of the stable patch requests for this:
> > > > "it's interesting how you deleted the changelog
> > > > comments here saying this was only needed for 4.11 and no older kernels
> > > > :)"
> > > >
> > > > and there's a follow up reply
> > > > (https://www.spinics.net/lists/stable/msg170125.html ) where Stephen
> > > > says:
> > > >
> > > > "At the time I only had reports of problem with 4.11.
> > > > But others ran into issue with 4.10 and 4.9"  
> > >
> > > The changelog was about where the problem was seen. It makes sense
> > > that this also occurs with other classes of storage devices;
> > > hadn't tried all the possible configurations.  
> > 
> > So, what does the maintainer of the driver recommend here?  Should I
> > backport this patch, or not?
> > 
> > thanks,
> > 
> > greg k-h
> > 
> 
> I was waiting for some feedback from Dexuan who has done most of the recent work on
> Hyper-V storage. His feedback is.
> 
> > Hi Stephen,
> > My understanding is that the patch was made to work around a host emulation
> > defect of SCSI DVD device, so old kernels should also need this patch, but I didn't
> > know it could fix SSD passthrough, and actually I was not aware of any bug 
> > related to SSD passthrough.
> > 
> > Thanks,
> > -- Dexuan
> 
> So yes, I think the backport is appropriate. The SSD fix is an added beneficial
> side effect.

Ok, now queued up...

greg k-h