Re: [Qemu-devel] [PATCH for-2.4 v2 0/2] vhost: check if vhost has capacity for hotplugged memory

[Michael S. Tsirkin]

On Wed, Jul 29, 2015 at 01:49:47PM +0200, Igor Mammedov wrote:
> v1->v2:
>   * replace probbing with checking for
>     /sys/module/vhost/parameters/max_mem_regions and
>     if it's missing has non wrong value return
>     hardcoded legacy limit (64 slots).
> 
> it's defensive patchset which helps to avoid QEMU crashing
> at memory hotplug time by checking that vhost has free capacity
> for an additional memory slot.

What if vhost is added after memory hotplug? Don't you need
to check that as well?


> 
> Igor Mammedov (2):
>   vhost: add vhost_has_free_slot() interface
>   pc-dimm: add vhost slots limit check before commiting to hotplug
> 
>  hw/mem/pc-dimm.c                  |  7 +++++++
>  hw/virtio/vhost-backend.c         | 21 ++++++++++++++++++++-
>  hw/virtio/vhost-user.c            |  8 +++++++-
>  hw/virtio/vhost.c                 | 21 +++++++++++++++++++++
>  include/hw/virtio/vhost-backend.h |  2 ++
>  include/hw/virtio/vhost.h         |  1 +
>  stubs/Makefile.objs               |  1 +
>  stubs/vhost.c                     |  6 ++++++
>  8 files changed, 65 insertions(+), 2 deletions(-)
>  create mode 100644 stubs/vhost.c
> 
> -- 
> 1.8.3.1