> From: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx>
> Sent: Wednesday, October 13, 2021 8:11 PM
>
> The VIRTIO_IOMMU_F_BYPASS_CONFIG feature adds a new flag to the
> ATTACH
> request, that creates a bypass domain. Use it to enable identity
> domains.
>
> When VIRTIO_IOMMU_F_BYPASS_CONFIG is not supported by the device,
> we
> currently fail attaching to an identity domain. Future patches will
> instead create identity mappings in this case.
>
> Signed-off-by: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx>
> ---
> drivers/iommu/virtio-iommu.c | 20 +++++++++++++++++++-
> 1 file changed, 19 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iommu/virtio-iommu.c b/drivers/iommu/virtio-iommu.c
> index 80930ce04a16..ee8a7afd667b 100644
> --- a/drivers/iommu/virtio-iommu.c
> +++ b/drivers/iommu/virtio-iommu.c
> @@ -71,6 +71,7 @@ struct viommu_domain {
> struct rb_root_cached mappings;
>
> unsigned long nr_endpoints;
> + bool bypass;
> };
>
> struct viommu_endpoint {
> @@ -587,7 +588,9 @@ static struct iommu_domain
> *viommu_domain_alloc(unsigned type)
> {
> struct viommu_domain *vdomain;
>
> - if (type != IOMMU_DOMAIN_UNMANAGED && type !=
> IOMMU_DOMAIN_DMA)
> + if (type != IOMMU_DOMAIN_UNMANAGED &&
> + type != IOMMU_DOMAIN_DMA &&
> + type != IOMMU_DOMAIN_IDENTITY)
> return NULL;
>
> vdomain = kzalloc(sizeof(*vdomain), GFP_KERNEL);
> @@ -630,6 +633,17 @@ static int viommu_domain_finalise(struct
> viommu_endpoint *vdev,
> vdomain->map_flags = viommu->map_flags;
> vdomain->viommu = viommu;
>
> + if (domain->type == IOMMU_DOMAIN_IDENTITY) {
> + if (!virtio_has_feature(viommu->vdev,
> + VIRTIO_IOMMU_F_BYPASS_CONFIG))
> {
> + ida_free(&viommu->domain_ids, vdomain->id);
> + vdomain->viommu = 0;
> + return -EOPNOTSUPP;
> + }
> +
> + vdomain->bypass = true;
> + }
> +
move to the start of the function, then no need for above cleanup.
> return 0;
> }
>
> @@ -691,6 +705,9 @@ static int viommu_attach_dev(struct iommu_domain
> *domain, struct device *dev)
> .domain = cpu_to_le32(vdomain->id),
> };
>
> + if (vdomain->bypass)
> + req.flags |=
> cpu_to_le32(VIRTIO_IOMMU_ATTACH_F_BYPASS);
> +
> for (i = 0; i < fwspec->num_ids; i++) {
> req.endpoint = cpu_to_le32(fwspec->ids[i]);
>
> @@ -1132,6 +1149,7 @@ static unsigned int features[] = {
> VIRTIO_IOMMU_F_DOMAIN_RANGE,
> VIRTIO_IOMMU_F_PROBE,
> VIRTIO_IOMMU_F_MMIO,
> + VIRTIO_IOMMU_F_BYPASS_CONFIG,
> };
>
> static struct virtio_device_id id_table[] = {
> --
> 2.33.0
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