Re: [Libvir] [RFC] Check host's minimum memory.
On Thu, Mar 08, 2007 at 01:03:48PM +0000, Daniel P. Berrange wrote:
On Thu, Mar 08, 2007 at 05:33:45PM +0900, Atsushi SAKAI wrote:
> Hi, Dan
>
> I and Sunou investivate this issue.
>
> virsh setmem commands directry writes xenstore(memory/target)
> by using xenStoreDomainSetMemory()(a)xs_internal.c.
> This data (memory/target) is read by PVdomain balloon driver directly.
> As you know, xenstore just pass through the data between inter domain.
> For this reason, virsh setmem must protect at xs_internal.c not on Xen-side
Ahhh, yes that makes sense. So looks like we have no choice but to
put some protection in libvirt here. Lets have a patch which applies
to xs_internal.c only, and protects Dom0 with a limit of 64 MB. This
avoids imposing policy on non-Dom0, or QEMU/KVM guests.
I applied the following patch which:
1/ find the places where we had an arbitrary memory value set or
tested, use MIN_XEN_GUEST_SIZE defined as 64 as the base minimum
and 2 * MIN_XEN_GUEST_SIZE for default when not defined
1/ add the protection to xenStoreDomainSetMemory, MIN_XEN_GUEST_SIZE
for guests and 2 * MIN_XEN_GUEST_SIZE for Dom0
of course the actual values selected can be argued about but at least I think
the place which are affected are now well isolated,
Daniel
--
Red Hat Virtualization group http://redhat.com/virtualization/
Daniel Veillard | virtualization library http://libvirt.org/
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Attachments:
- min_memory.patch (text/plain — 5.8 KB)