Re: [Xen-devel] [BUG] xen-mceinj tool testing cause dom0 crash

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 09.11.17 at 02:44, <haozhong.zhang@xxxxxxxxx> wrote:
> On 11/07/17 01:37 -0700, Jan Beulich wrote:
>> I don't believe a crash is the expected outcome here.
>>
> 
> This test case injects two errors to the same dom0 page. During the
> first injection, offline_page() is called to set PGC_broken flag of
> that page. During the second injection, offline_page() detects the
> same broken page is touched again, and then tries to shutdown the page
> owner, i.e. dom0 in this case:
> 
>     /*
>      * NB. When broken page belong to guest, usually hypervisor will
>      * notify the guest to handle the broken page. However, hypervisor
>      * need to prevent malicious guest access the broken page again.
>      * Under such case, hypervisor shutdown guest, preventing recursive mce.
>      */
>     if ( (pg->count_info & PGC_broken) && (owner = page_get_owner(pg)) )
>     {
>         *status = PG_OFFLINE_AGAIN;
>         domain_shutdown(owner, SHUTDOWN_crash);
>         return 0;
>     }
> 
> So I think Dom0 crash and the following machine reboot are the
> expected behaviors here.

Oh, that's quite unfortunate - there should at least be a log
message associated with that; I can't see why this isn't
domain_crash() in the first place (which would leave a log
message); I'm queuing a patch (but for after 4.10 only).

Jan


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