On 03.02.20 19:31, David Hildenbrand wrote:
> Let's implement ram_block_resized().
>
> Note: Resizing is currently only allowed during reboot or when migration
> starts.
>
> Cc: "Dr. David Alan Gilbert" <dgilb...@redhat.com>
> Cc: Paolo Bonzini <pbonz...@redhat.com>
> Cc: Markus Armbruster <arm...@redhat.com>
> Cc: Alex Williamson <alex.william...@redhat.com>
> Signed-off-by: David Hildenbrand <da...@redhat.com>
> ---
> util/vfio-helpers.c | 13 +++++++++++++
> 1 file changed, 13 insertions(+)
>
> diff --git a/util/vfio-helpers.c b/util/vfio-helpers.c
> index 71e02e7f35..57d77e9480 100644
> --- a/util/vfio-helpers.c
> +++ b/util/vfio-helpers.c
> @@ -395,11 +395,24 @@ static void
> qemu_vfio_ram_block_removed(RAMBlockNotifier *n,
> }
> }
>
> +static void qemu_vfio_ram_block_resized(RAMBlockNotifier *n, void *host,
> + size_t oldsize, size_t newsize)
> +{
> + QEMUVFIOState *s = container_of(n, QEMUVFIOState, ram_notifier);
> + if (host) {
> + trace_qemu_vfio_ram_block_resized(s, host, oldsize, newsize);
> + /* Note: Not atomic - we need a new ioctl for that. */
> + qemu_vfio_ram_block_removed(n, host, oldsize);
> + qemu_vfio_ram_block_added(n, host, newsize);
> + }
> +}
> +
> static void qemu_vfio_open_common(QEMUVFIOState *s)
> {
> qemu_mutex_init(&s->lock);
> s->ram_notifier.ram_block_added = qemu_vfio_ram_block_added;
> s->ram_notifier.ram_block_removed = qemu_vfio_ram_block_removed;
> + s->ram_notifier.ram_block_resized = qemu_vfio_ram_block_resized;
> s->low_water_mark = QEMU_VFIO_IOVA_MIN;
> s->high_water_mark = QEMU_VFIO_IOVA_MAX;
> ram_block_notifier_add(&s->ram_notifier);
>
I'll most probably change the handling, to reserve the IOVA for max_size
of the ram block, but only map the usable size. Addresses in the IOVA
won't be reused.
If I am not wrong, hotplugging+unplugging DIMMs a couple of times can
easily eat up the whole IOVA. Same would be true on every resize.
At this point, I really detest ram block notifiers. :)
--
Thanks,
David / dhildenb
