Hi Jean,
On 1/27/22 3:29 PM, Jean-Philippe Brucker wrote:
> The driver can create a bypass domain by passing the
> VIRTIO_IOMMU_ATTACH_F_BYPASS flag on the ATTACH request. Bypass domains
> perform slightly better than domains with identity mappings since they
> skip translation.
>
> Signed-off-by: Jean-Philippe Brucker <jean-phili...@linaro.org>
> ---
> hw/virtio/virtio-iommu.c | 32 ++++++++++++++++++++++++++++++--
> 1 file changed, 30 insertions(+), 2 deletions(-)
>
> diff --git a/hw/virtio/virtio-iommu.c b/hw/virtio/virtio-iommu.c
> index ec02029bb6..a112428c65 100644
> --- a/hw/virtio/virtio-iommu.c
> +++ b/hw/virtio/virtio-iommu.c
> @@ -43,6 +43,7 @@
>
> typedef struct VirtIOIOMMUDomain {
> uint32_t id;
> + bool bypass;
I am afraid this will break the migration if you don't change
vmstate_domain.
See static const VMStateDescription vmstate_domain.
Also you need to migrate the new bypass field.
Logically we should handle this with a vmstate subsection I think to
handle migration of older devices. However I doubt the device has been
used in production environment supporting migration so my guess is we
may skip that burden and just add the missing field. Adding Juan, Dave &
Peter for advices.
Thanks
Eric
> GTree *mappings;
> QLIST_HEAD(, VirtIOIOMMUEndpoint) endpoint_list;
> } VirtIOIOMMUDomain;
> @@ -258,12 +259,16 @@ static void virtio_iommu_put_endpoint(gpointer data)
> }
>
> static VirtIOIOMMUDomain *virtio_iommu_get_domain(VirtIOIOMMU *s,
> - uint32_t domain_id)
> + uint32_t domain_id,
> + bool bypass)
> {
> VirtIOIOMMUDomain *domain;
>
> domain = g_tree_lookup(s->domains, GUINT_TO_POINTER(domain_id));
> if (domain) {
> + if (domain->bypass != bypass) {
> + return NULL;
> + }
> return domain;
> }
> domain = g_malloc0(sizeof(*domain));
> @@ -271,6 +276,7 @@ static VirtIOIOMMUDomain
> *virtio_iommu_get_domain(VirtIOIOMMU *s,
> domain->mappings = g_tree_new_full((GCompareDataFunc)interval_cmp,
> NULL, (GDestroyNotify)g_free,
> (GDestroyNotify)g_free);
> + domain->bypass = bypass;
> g_tree_insert(s->domains, GUINT_TO_POINTER(domain_id), domain);
> QLIST_INIT(&domain->endpoint_list);
> trace_virtio_iommu_get_domain(domain_id);
> @@ -334,11 +340,16 @@ 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);
> + uint32_t flags = le32_to_cpu(req->flags);
> VirtIOIOMMUDomain *domain;
> VirtIOIOMMUEndpoint *ep;
>
> trace_virtio_iommu_attach(domain_id, ep_id);
>
> + if (flags & ~VIRTIO_IOMMU_ATTACH_F_BYPASS) {
> + return VIRTIO_IOMMU_S_INVAL;
> + }
> +
> ep = virtio_iommu_get_endpoint(s, ep_id);
> if (!ep) {
> return VIRTIO_IOMMU_S_NOENT;
> @@ -356,7 +367,12 @@ static int virtio_iommu_attach(VirtIOIOMMU *s,
> }
> }
>
> - domain = virtio_iommu_get_domain(s, domain_id);
> + domain = virtio_iommu_get_domain(s, domain_id,
> + flags & VIRTIO_IOMMU_ATTACH_F_BYPASS);
> + if (!domain) {
> + /* Incompatible bypass flag */
> + return VIRTIO_IOMMU_S_INVAL;
> + }
> QLIST_INSERT_HEAD(&domain->endpoint_list, ep, next);
>
> ep->domain = domain;
> @@ -419,6 +435,10 @@ static int virtio_iommu_map(VirtIOIOMMU *s,
> return VIRTIO_IOMMU_S_NOENT;
> }
>
> + if (domain->bypass) {
> + return VIRTIO_IOMMU_S_INVAL;
> + }
> +
> interval = g_malloc0(sizeof(*interval));
>
> interval->low = virt_start;
> @@ -464,6 +484,11 @@ static int virtio_iommu_unmap(VirtIOIOMMU *s,
> if (!domain) {
> return VIRTIO_IOMMU_S_NOENT;
> }
> +
> + if (domain->bypass) {
> + return VIRTIO_IOMMU_S_INVAL;
> + }
> +
> interval.low = virt_start;
> interval.high = virt_end;
>
> @@ -780,6 +805,9 @@ static IOMMUTLBEntry
> virtio_iommu_translate(IOMMUMemoryRegion *mr, hwaddr addr,
> entry.perm = flag;
> }
> goto unlock;
> + } else if (ep->domain->bypass) {
> + entry.perm = flag;
> + goto unlock;
> }
>
> found = g_tree_lookup_extended(ep->domain->mappings,
> (gpointer)(&interval),
