Re: [Qemu-devel] [PATCH for-4.2 v10 07/15] virtio-iommu: Implement attach/detach command

[Peter Xu <peterx@redhat.com>]

On Tue, Jul 30, 2019 at 07:21:29PM +0200, Eric Auger wrote:
> This patch implements the endpoint attach/detach to/from
> a domain.
> 
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
> 
> ---
> ---
>  hw/virtio/virtio-iommu.c | 40 ++++++++++++++++++++++++++++++++++------
>  1 file changed, 34 insertions(+), 6 deletions(-)
> 
> diff --git a/hw/virtio/virtio-iommu.c b/hw/virtio/virtio-iommu.c
> index 77dccecc0a..5ea0930cc2 100644
> --- a/hw/virtio/virtio-iommu.c
> +++ b/hw/virtio/virtio-iommu.c
> @@ -80,8 +80,8 @@ static void virtio_iommu_detach_endpoint_from_domain(viommu_endpoint *ep)
>      ep->domain = NULL;
>  }
>  
> -viommu_endpoint *virtio_iommu_get_endpoint(VirtIOIOMMU *s, uint32_t ep_id);
> -viommu_endpoint *virtio_iommu_get_endpoint(VirtIOIOMMU *s, uint32_t ep_id)

These lines were just introduced in previous patch, I wanted to ask
why the definition was needed but I don't know whether it'll be used
in follow up patches.  Looks like it wasn't really used.

I would prefer patches like these to be squashed together not only to
avoid the maintainance of diffs like this between patches, but also as
a reviewer it'll be easier too when with all the contexts together.
But I won't ask for it because it can be a personal preference only...

> +static viommu_endpoint *virtio_iommu_get_endpoint(VirtIOIOMMU *s,
> +                                                  uint32_t ep_id)
>  {
>      viommu_endpoint *ep;
>  
> @@ -110,8 +110,8 @@ static void virtio_iommu_put_endpoint(gpointer data)
>      g_free(ep);
>  }
>  
> -viommu_domain *virtio_iommu_get_domain(VirtIOIOMMU *s, uint32_t domain_id);
> -viommu_domain *virtio_iommu_get_domain(VirtIOIOMMU *s, uint32_t domain_id)
> +static viommu_domain *virtio_iommu_get_domain(VirtIOIOMMU *s,
> +                                              uint32_t domain_id)
>  {
>      viommu_domain *domain;
>  
> @@ -187,10 +187,27 @@ static int virtio_iommu_attach(VirtIOIOMMU *s,
>  {
>      uint32_t domain_id = le32_to_cpu(req->domain);
>      uint32_t ep_id = le32_to_cpu(req->endpoint);
> +    viommu_domain *domain;
> +    viommu_endpoint *ep;
>  
>      trace_virtio_iommu_attach(domain_id, ep_id);
>  
> -    return VIRTIO_IOMMU_S_UNSUPP;
> +    ep = virtio_iommu_get_endpoint(s, ep_id);
> +    if (ep->domain) {
> +        /*
> +         * the device is already attached to a domain,
> +         * detach it first
> +         */
> +        virtio_iommu_detach_endpoint_from_domain(ep);

Hmm... so this can be called without virtio_iommu_put_endpoint().
Then I think we'd better move:

        g_tree_unref(ep->domain->mappings);

From virtio_iommu_put_endpoint() to inside
virtio_iommu_detach_endpoint_from_domain() otherwise domain refs might
leak?

> +    }
> +
> +    domain = virtio_iommu_get_domain(s, domain_id);
> +    QLIST_INSERT_HEAD(&domain->endpoint_list, ep, next);
> +
> +    ep->domain = domain;
> +    g_tree_ref(domain->mappings);
> +
> +    return VIRTIO_IOMMU_S_OK;
>  }

Regards,

-- 
Peter Xu