Re: [Xen-devel] EFI Xen unstable crashes on Dell E6410 when calling efi_get_time.

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 22.10.14 at 13:01, <andrew.cooper3@xxxxxxxxxx> wrote:
> On 22/10/14 11:22, Jan Beulich wrote:
>>>>> On 22.10.14 at 11:45, <andrew.cooper3@xxxxxxxxxx> wrote:
>>> For EFI calls, we run on the efi pagetables, not the idle pagetables, so
>>> I am not surprised that the assertion has failed.  I suspect that the
>>> pagefault hander for hypervisor faults needs to become wise to the fact
>>> that we may receive a fault when calling into the firmware.  As all the
>>> efi pagetables are xenheap pages, there is nothing conceptually wrong
>>> with using map_domain_page() to do the walk.
>> I'm not sure it's worth taking care of this special case. But yes, if
>> we really want to, extending the condition to also consider
>> efi_l4_pgtable would seem the right thing to do.
> 
> I think being able to do a pagetable walk from an EFI fault would be
> useful, even if only to aid debugging.  In this case, a non-debug build
> would successfully perform the walk.
> 
> I have had a quick go, but it is rather hard to get the efi_l4_pgtable
> symbol available to use in domain_page.c without some gross extern'ing. 
> It would be a nice fix if anyone has sufficient tuits.

I'll take a look, but likely only next week.

Jan


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