Re: [PATCH] virtio-balloon-pci: Allow setting nvectors, so we can use MSI-X

[Philippe Mathieu-Daudé]

Hi Reza,

On 16/12/24 17:31, Reza Arbab wrote:
> Most virtio-pci devices allow MSI-X. Add it to virtio-balloon-pci, but
> only enable it in new machine types, so we don't break migration of
> existing machine types between different qemu versions.
>
> This copies what was done for virtio-rng-pci in:
> 9ea02e8f1306 ("virtio-rng-pci: Allow setting nvectors, so we can use MSI-X")
> bad9c5a5166f ("virtio-rng-pci: fix migration compat for vectors")
> 62bdb8871512 ("virtio-rng-pci: fix transitional migration compat for vectors")
>
> Signed-off-by: Reza Arbab <arbab@linux.ibm.com>
> ---
>   hw/core/machine.c              |  6 +++++-
>   hw/virtio/virtio-balloon-pci.c | 13 +++++++++++++
>   2 files changed, 18 insertions(+), 1 deletion(-)


> diff --git a/hw/virtio/virtio-balloon-pci.c b/hw/virtio/virtio-balloon-pci.c
> index ce2645ba7187..1c2b071eff0c 100644
> --- a/hw/virtio/virtio-balloon-pci.c
> +++ b/hw/virtio/virtio-balloon-pci.c
> @@ -35,11 +35,23 @@ struct VirtIOBalloonPCI {
>       VirtIOBalloon vdev;
>   };
>   
> +static Property virtio_balloon_properties[] = {
> +    DEFINE_PROP_BIT("ioeventfd", VirtIOPCIProxy, flags,
> +                    VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT, true),
> +    DEFINE_PROP_UINT32("vectors", VirtIOPCIProxy, nvectors,
> +                       DEV_NVECTORS_UNSPECIFIED),
> +    DEFINE_PROP_END_OF_LIST(),

You shouldn't use that anymore since commit 5fcabe628b8
("include/hw/qdev-properties: Remove DEFINE_PROP_END_OF_LIST").

Also, this array can be declared const.

> +};