Re: [Qemu-devel] [PATCH v4 4/7] pc: fix QEMU crashing when more than ~50 memory hotplugged

[Michael S. Tsirkin]

On Thu, Jul 09, 2015 at 03:43:01PM +0200, Paolo Bonzini wrote:
> 
> 
> On 09/07/2015 15:06, Michael S. Tsirkin wrote:
> > > QEMU asserts in vhost due to hitting vhost backend limit
> > > on number of supported memory regions.
> > > 
> > > Describe all hotplugged memory as one continuos range
> > > to vhost with linear 1:1 HVA->GPA mapping in backend.
> > > 
> > > Signed-off-by: Igor Mammedov <address@hidden>
> >
> > Hmm - a bunch of work here to recombine MRs that memory listener
> > interface breaks up.  In particular KVM could benefit from this too (on
> > workloads that change the table a lot).  Can't we teach memory core to
> > pass hva range as a single continuous range to memory listeners?
> 
> Memory listeners are based on memory regions, not HVA ranges.
> 
> Paolo

Many listeners care about HVA ranges. I know KVM and vhost do.
I guess we could create dummy MRs to fill in the holes left by
memory hotplug? vhost already has logic to recombine
consequitive chunks created by memory core.

-- 
MST