Re: Qemu-upstream with Xen

[Jean-Yves Migeon <jeanyves.migeon%free.fr@localhost>]

Le 13/06/2012 15:59, Roger Pau Monné a écrit :
> On Wed, Jun 13, 2012 at 2:22 PM, Jean-Yves Migeon
> <jeanyves.migeon%free.fr@localhost> wrote:
> > Le 13/06/2012 13:05, Roger Pau Monné a écrit :
> >
> > > I've debugged this a little bit more, and I've found that
> > > privpgop_fault gets called, and tries to map the address again 
> > > after
> > > the call to xc_domain_add_to_physmap. But the call to pmap_enter_ma
> > > returns the error 'EFAULT', and thus the segfault in Qemu. The
> > > previous call to this function in IOCTL_PRIVCMD_MMAPBATCH (which 
> > > tries
> > > to detect which pages can be mapped) didn't mark this page as 
> > > invalid,
> > > so something must have changed in between... Suggestions are 
> > > welcome.
> [...]
> vaddr: 7f7feec00000 (which corresponds to the Qemu vaddr that
> generates the segfault)
> paddr: 3f800000
> prot: 3
> flags: 35
> domid: 1 (which belongs to the domu I'm trying to create)

Good, thanks.

> > Can you obtain the arguments passed to the hypercall?
>
> The arguments passed to the hypercall (HYPERVISOR_mmu_update), are:
>
> ptr: 2014b9000
> val: 800000003f800067
>
> And of course it returns < 0, which causes the error.

Nothing suspicious here. 3f800000 is reported as a hole by e820 map 
though:

> (XEN) HVM1:  HOLE: 00000000:3f800000 - 00000000:fc000000
> (XEN) HVM1:  [03]: 00000000:fc000000 - 00000001:00000000: RESERVED

Is the P2M table (xpmap_phys_to_machine_mapping) entry for this address 
marked as INVALID_MFN?

--
Jean-Yves Migeon