If there is no further feedback, I'll queue this myself shortly.

Stumbling over "x-ignore-shared" migration support for virtio-mem on
my todo list, I remember talking to Dave G. a while ago about how
ram_block_discard_range() in MAP_PIRVATE file mappings is possibly
harmful when the file is used somewhere else -- for example, with VM
templating in multiple VMs.

This series adds a warning to ram_block_discard_range() in that problematic
case and adds "x-ignore-shared" migration support for virtio-mem, which
is pretty straight-forward. The last patch also documents how VM templating
interacts with virtio-mem.

v1 -> v2:
- Pick up tags
- "virtio-mem: Support "x-ignore-shared" migration"
 -> Fix spelling mistake

Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Juan Quintela <quintela@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Leonardo Bras <leobras@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Philippe Mathieu-Daudé" <philmd@linaro.org>
Cc: Peng Tao <tao.peng@linux.alibaba.com>
Cc: Mario Casquero <mcasquer@redhat.com>

David Hildenbrand (4):
  softmmu/physmem: Warn with ram_block_discard_range() on MAP_PRIVATE
    file mapping
  virtio-mem: Skip most of virtio_mem_unplug_all() without plugged
    memory
  migration/ram: Expose ramblock_is_ignored() as
    migrate_ram_is_ignored()
  virtio-mem: Support "x-ignore-shared" migration

 hw/virtio/virtio-mem.c   | 67 ++++++++++++++++++++++++++++------------
 include/migration/misc.h |  1 +
 migration/postcopy-ram.c |  2 +-
 migration/ram.c          | 14 ++++-----
 migration/ram.h          |  3 +-
 softmmu/physmem.c        | 18 +++++++++++
 6 files changed, 76 insertions(+), 29 deletions(-)

-- 
2.41.0

On Thu, Jul 06, 2023 at 09:56:05AM +0200, David Hildenbrand wrote:
> If there is no further feedback, I'll queue this myself shortly.
> 
> Stumbling over "x-ignore-shared" migration support for virtio-mem on
> my todo list, I remember talking to Dave G. a while ago about how
> ram_block_discard_range() in MAP_PIRVATE file mappings is possibly
> harmful when the file is used somewhere else -- for example, with VM
> templating in multiple VMs.
> 
> This series adds a warning to ram_block_discard_range() in that problematic
> case and adds "x-ignore-shared" migration support for virtio-mem, which
> is pretty straight-forward. The last patch also documents how VM templating
> interacts with virtio-mem.
> 
> v1 -> v2:
> - Pick up tags
> - "virtio-mem: Support "x-ignore-shared" migration"
>  -> Fix spelling mistake

Reviewed-by: Michael S. Tsirkin <mst@redhat.com>


> Cc: "Michael S. Tsirkin" <mst@redhat.com>
> Cc: Juan Quintela <quintela@redhat.com>
> Cc: Peter Xu <peterx@redhat.com>
> Cc: Leonardo Bras <leobras@redhat.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: "Philippe Mathieu-Daudé" <philmd@linaro.org>
> Cc: Peng Tao <tao.peng@linux.alibaba.com>
> Cc: Mario Casquero <mcasquer@redhat.com>
> 
> David Hildenbrand (4):
>   softmmu/physmem: Warn with ram_block_discard_range() on MAP_PRIVATE
>     file mapping
>   virtio-mem: Skip most of virtio_mem_unplug_all() without plugged
>     memory
>   migration/ram: Expose ramblock_is_ignored() as
>     migrate_ram_is_ignored()
>   virtio-mem: Support "x-ignore-shared" migration
> 
>  hw/virtio/virtio-mem.c   | 67 ++++++++++++++++++++++++++++------------
>  include/migration/misc.h |  1 +
>  migration/postcopy-ram.c |  2 +-
>  migration/ram.c          | 14 ++++-----
>  migration/ram.h          |  3 +-
>  softmmu/physmem.c        | 18 +++++++++++
>  6 files changed, 76 insertions(+), 29 deletions(-)
> 
> -- 
> 2.41.0

On 06.07.23 16:03, Michael S. Tsirkin wrote:
> On Thu, Jul 06, 2023 at 09:56:05AM +0200, David Hildenbrand wrote:
>> If there is no further feedback, I'll queue this myself shortly.
>>
>> Stumbling over "x-ignore-shared" migration support for virtio-mem on
>> my todo list, I remember talking to Dave G. a while ago about how
>> ram_block_discard_range() in MAP_PIRVATE file mappings is possibly
>> harmful when the file is used somewhere else -- for example, with VM
>> templating in multiple VMs.
>>
>> This series adds a warning to ram_block_discard_range() in that problematic
>> case and adds "x-ignore-shared" migration support for virtio-mem, which
>> is pretty straight-forward. The last patch also documents how VM templating
>> interacts with virtio-mem.
>>
>> v1 -> v2:
>> - Pick up tags
>> - "virtio-mem: Support "x-ignore-shared" migration"
>>   -> Fix spelling mistake
> 
> Reviewed-by: Michael S. Tsirkin <mst@redhat.com>

Thanks, I queued this to

https://github.com/davidhildenbrand/qemu.git mem-next

-- 
Cheers,

David / dhildenb