Re: [V10 PATCH 0/4] pvh dom0 patches...

[Mukesh Rathor <mukesh.rathor@oracle.com>]

On Wed, 30 Apr 2014 11:12:16 -0700
Mukesh Rathor <mukesh.rathor@oracle.com> wrote:

> On Wed, 30 Apr 2014 16:11:39 +0200
> Roger Pau Monné <roger.pau@citrix.com> wrote:
> 
> > On 30/04/14 03:06, Mukesh Rathor wrote:
> .....
> 
> > Hello Mukesh,
> > 
> > Thanks for the new version, unfortunately when trying to boot
> > FreeBSD Dom0 with this version I get the following hypervisor crash
> > (it works fine with previous versions):
> 
> Aha, Jan, there's the vioapic crash!! Roger, see:
> 
> http://www.gossamer-threads.com/lists/xen/devel/325784
> 
> I had seen this few weeks ago, but could not reproduce last week 
> despite several attempts. You are seeing this in V10 because I dropped
> the vioapic patch from V9 (included below).
> 
> BTW, since I'm not able to reproduce this, can you kindly check
> where the ept violation is coming from? Is that on an io space?
> Also, our binaries don't match, so can you please confirm it's the 
> call from:
> 
> hvm_hap_nested_page_fault():
>     if ( (p2mt == p2m_mmio_dm) ||
>          (access_w && (p2mt == p2m_ram_ro)) )
>     {
>         put_gfn(p2m->domain, gfn);
>         if ( !handle_mmio() )   <==========
>             hvm_inject_hw_exception(TRAP_gp_fault, 0);
> 
> In which case, what's the p2mt?
> 

Hey Roger,

I tried few things, but still could not reproduce. I saw it few weeks
ago, and I think I misread the code thinking hvm_hap_nested_page_fault
was calling handle_mmio unconditionally, and quickly came up with
the vioapic patch for v9. 

So, can you please try with the vioapic patch. Then two things will
happen:

  1. The ept violation is genuine, in which case it will return back
     successfully to ept_handle_violation which will print the gfn/mfn
     info for further debug.
  2. the emulation will be handled, in which case we need to know what
     was it, mmio_dm or ram_ro, and where it came from in dom0? Both are
     unexpected.

thanks for the help,
mukesh


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