Re: [Qemu-devel] [PATCH v4 0/3] vhost: check if vhost has capacity for hotplugged memory

[Igor Mammedov]

On Tue,  6 Oct 2015 10:37:26 +0200
Igor Mammedov <address@hidden> wrote:

> v3->v4:
>   * rescan all vhost backends when checking for limit (Michael S. Tsirkin)
>   * check that used slots are less than limit of new backend (Michael S. 
> Tsirkin)
ping

> v2->v3:
>   * add refcounting of limit by # vhost devices,
>     and make vhost_has_free_slot() return true if no vhost devices
>     are present at current moment
>   * move limit initialization to vhost_dev_init()
>   * fail vhost backend intialization if memslots number is more than its 
> supported limit
> 
> 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.
> 
> Igor Mammedov (3):
>   vhost: add vhost_has_free_slot() interface
>   pc-dimm: add vhost slots limit check before commiting to hotplug
>   vhost: fail backend intialization if memslots number is more than its
>     supported limit
> 
>  hw/mem/pc-dimm.c                  |  7 +++++++
>  hw/virtio/vhost-backend.c         | 19 +++++++++++++++++++
>  hw/virtio/vhost-user.c            |  6 ++++++
>  hw/virtio/vhost.c                 | 27 +++++++++++++++++++++++++++
>  include/hw/virtio/vhost-backend.h |  2 ++
>  include/hw/virtio/vhost.h         |  2 ++
>  stubs/Makefile.objs               |  1 +
>  stubs/vhost.c                     |  6 ++++++
>  8 files changed, 70 insertions(+)
>  create mode 100644 stubs/vhost.c
>