RE: Installing WinPV drivers on Windows 2019

[Owen Smith <owen.smith@xxxxxxxxxx>]

Interestingly, the Citrix drivers are using MmAllocatePagesForMdlEx and are not 
hitting this 0x139 BSOD.

The patch Paul mentioned was reverted after this update was pushed out
https://support.microsoft.com/en-us/help/4458469/windows-10-update-kb4458469

Owen

> -----Original Message-----
> From: win-pv-devel [mailto:win-pv-devel-bounces@xxxxxxxxxxxxxxxxxxxx] On
> Behalf Of Jan Bakuwel
> Sent: 09 June 2020 10:34
> To: paul@xxxxxxx; win-pv-devel@xxxxxxxxxxxxxxxxxxxx
> Subject: Re: Installing WinPV drivers on Windows 2019
> 
> [CAUTION - EXTERNAL EMAIL] DO NOT reply, click links, or open attachments
> unless you have verified the sender and know the content is safe.
> 
> Hi Paul,
> 
> On 9/06/20 7:27 pm, Paul Durrant wrote:
> >> -----Original Message-----
> >> From: Jan Bakuwel <jan.bakuwel@xxxxxxxxx>
> >> Sent: 09 June 2020 03:33
> >> To: paul@xxxxxxx; win-pv-devel@xxxxxxxxxxxxxxxxxxxx
> >> Subject: Re: Installing WinPV drivers on Windows 2019
> >>
> >> Hi Paul,
> >>> Hi Jan,
> >>>
> >>>     Oddly the summary analysis below fingers the network driver but
> >>> when I pull the dump into windbg,
> >> it clearly points at a stack overflow in a thread starting in xenvbd...
> >>
> >> I'm not familiar with Windows driver debugging but trust you when you
> >> say it is :-)
> >>
> >> Any suggestions where we can go from here?
> >>
> > Hi Jan,
> >
> > I think you are hitting a bug in Windows itself that was worked around by 
> > this
> commit in XENVIF:
> >
> > https://xenbits.xen.org/gitweb/?p=pvdrivers/win/xenvif.git;a=commit;h=
> > 4f85d00477b0931d4367a34de4f84d54b0f04d4e
> >
> > ---
> > Replace uses of MmAllocatePagesForMdlEx in __AllocatePage
> >
> > Windows appears to have an edge case bug in which zeroing memory using
> > MmAllocatePAgesForMdlEx (which in Win 10 1803 happens even if you
> > specify MM_DONT_ZERO_ALLOCATION) can cause a BSOD 139 1e.
> >
> > This commit uses MmAllocateContinguousMemorySpecifyCache
> > to allocate memory instead, then builds and Mdl to wrap it up.
> >
> > __AllocatePages is left unchanged (as we don't want to allocate
> > multiple contiguous pages).  This issue has not been seen outside of
> > xenvif calls to __AllocatePage and we expect a fix to the underlying
> > Windows problem in the near future
> >
> > Signed-off-by: Ben.Chalmers <ben.chalmers@xxxxxxxxxx>
> > ---
> >
> > Firstly, is your installation fully updated?
> 
> That depends on Microsoft :-) ... the server is set to auto update.
> 
> I just hit "Check for Updates" and the server pulled in three updates:
> one for Windows Defender, one KB4551853 and one for Adobe Flash, none of
> them related.
> 
> > If so then it appears Microsoft have *still* not fixed this, despite it 
> > being
> identified in 2018, in which case I will clone the above commit into XENVBD 
> and
> also amend any other drivers using MmAllocatePagesForMdlEx() with that
> option.
> 
> I think it's safe to conclude that Microsoft indeed has not fixed this.
> Not really surprising, eh?
> 
> Many thanks for your help, looking forward to the new drivers.
> 
> kind regards,
> Jan
> 
>