Re: crash in efi_runtime_call

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 17/04/15 12:17, Olaf Hering wrote:
> Since booting xen fails on my ProBook unless I specify "maxcpus=1" I
> tried the EFI firmware today. To my surprise it boots and finds all
> cpus. But once some efi driver in dom0 is loaded xen crashes. The same
> happens with xen-4.4 as included in SLE12.
>
> ...
> (XEN) Xen call trace:
> (XEN)    [<00000000aec1e8e1>] 00000000aec1e8e1
> (XEN)    [<ffff82d080222600>] efi_runtime_call+0x7f0/0x890
> (XEN)    [<ffff82d0801641a9>] do_platform_op+0x679/0x1670
> (XEN)    [<ffff82d08021dfb9>] syscall_enter+0xa9/0xae
> ....
>
> Can I do anything about it, or is this a firmware bug? I will move the
> offending efi driver away and try again.
>
> Olaf

This is a firmware bug.

> (XEN)  0000100000000-000023fffffff type=7 attr=000000000000000
> (XEN)  00000fec10000-00000fec10fff type=11 attr=8000000000000001
> (XEN)  00000fff40000-00000fff46fff type=11 attr=8000000000000000
> (XEN) Unknown cachability for MFNs 0xfff40-0xfff46

This unknown cacheability causes Xen not to make pagetables for the region.

There is a patch or two floating around the list, but currently no
resolution on the argument it created.

https://github.com/xenserver/xen-4.5.pg/blob/master/master/unknown-cacheability.patch
is the XenServer fix.

~Andrew