Re: Qemu-upstream with Xen

[Roger Pau Monné <roger.pau%entel.upc.edu@localhost>]

On Wed, Jun 13, 2012 at 5:46 PM, Jean-Yves Migeon
<jeanyves.migeon%free.fr@localhost> wrote:
> 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?

I'm not sure if this is correct, but I've done a:

pfn_to_mfn((0x3f800000 - XPMAP_OFFSET) >> PAGE_SHIFT) and it is 239540

Also, the syscall HYPERVISOR_mmu_update returns the error -22 (EINVAL).

Thanks.