RE: Installing WinPV drivers on Windows 2019

[Paul Durrant <xadimgnik@xxxxxxxxx>]

> -----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?

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.

  Paul