Re: [Xen-devel] Debian Wheezy installer crashes guest when EPT is enabled

["Jan Beulich" <jbeulich@xxxxxxxx>]

>>>> Wei Liu <wei.liu2@xxxxxxxxxx> 04/18/14 7:19 PM >>>
>On Fri, Apr 18, 2014 at 03:17:41PM +0100, Wei Liu wrote:
>> On Fri, Apr 18, 2014 at 03:08:04PM +0100, Wei Liu wrote:
>> > I see in the master tree that there are many changes to EPT lately. With
>> > the current master tree (as of c82fbfe), I cannot install Debian Wheezy
>> > in HVM mode when EPT is enabled. It used to work at d2b4c27.
>> > 
>> > One particular interesting changeset is aa9114ed ("x86/EPT: force
>> > re-evaluation of memory type as necessary"), because I saw the faulting
>> > VMEXIT reason to be EXIT_REASON_EPT_MISCONFIG. But I cannot see
>> > immediate connection.
>> > 
>> > The step to reproduce is easy:
>> > 0. get an Intel EPT capable machine (I have Xeon X3450)
>> > 1. grab Xen master tree and install
>> > 2. download debian-7.2.0-amd64-CD-1.iso from any Debian mirror and
>> >    install it in HVM mode, with HAP enabled
>> > 3. guest crashes soon after installer runs
>> 
>> ... and this guest has 5000MB RAM.  If RAM is set to 768MB guest doesn't
>> crash.

Interesting. I don't think I ever tried a guest this big, and I may have some 
difficulty
finding a suitable box (without pushing Dom0 below 1G). Would be interesting to 
see
whether other guests also have a problem when they're being given enough memory.

>FWIW I manually bisected the tree. First bad commit:
>
>commit 4d66f069d6abacd392f1301714fdfc64dc92917b
>Author: Jan Beulich <jbeulich@xxxxxxxx>
>Date:   Thu Apr 10 16:07:17 2014 +0200
>
>x86: fix pinned cache attribute handling
    
Now that's pretty surprising, I would have thought other changes are much more
likely to cause problems. But wait, what your log says is that memory allocation
failed - that's not as surprising in this context, since the number of page 
splits
certainly went up with all the recent changes (and what the change here did may
just have pushed it over the boundary).

Tim - any thought on the pool size and an eventual need to bump it?

Anyway, I'm going to be able to look at this in closer detail on Tuesday the 
earliest.

Jan


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel