Hi Niklas,
Thanks for following up with these patches
On Fri, Aug 25, 2023 at 05:21:25PM +0200, Niklas Schnelle wrote:
> Pull out the sync operation from viommu_map_pages() by implementing
> ops->iotlb_sync_map. This allows the common IOMMU code to map multiple
> elements of an sg with a single sync (see iommu_map_sg()). Furthermore,
> it is also a requirement for IOMMU_CAP_DEFERRED_FLUSH.
>
> Link: https://lore.kernel.org/lkml/[email protected]/
> Signed-off-by: Niklas Schnelle <[email protected]>
> ---
> drivers/iommu/virtio-iommu.c | 15 ++++++++++++++-
> 1 file changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iommu/virtio-iommu.c b/drivers/iommu/virtio-iommu.c
> index 3551ed057774..fb73dec5b953 100644
> --- a/drivers/iommu/virtio-iommu.c
> +++ b/drivers/iommu/virtio-iommu.c
> @@ -843,7 +843,7 @@ static int viommu_map_pages(struct iommu_domain *domain, unsigned long iova,
> .flags = cpu_to_le32(flags),
> };
>
> - ret = viommu_send_req_sync(vdomain->viommu, &map, sizeof(map));
> + ret = viommu_add_req(vdomain->viommu, &map, sizeof(map));
> if (ret) {
> viommu_del_mappings(vdomain, iova, end);
> return ret;
> @@ -909,9 +909,21 @@ static void viommu_iotlb_sync(struct iommu_domain *domain,
> {
> struct viommu_domain *vdomain = to_viommu_domain(domain);
>
> + if (!vdomain->nr_endpoints)
> + return;
I was wondering about these nr_endpoints checks, which seemed unnecessary:
if map()/unmap() were called with no attached endpoints, then no requests
were added to the queue, and viommu_sync_req() below is a nop.
But at least viommu_iotlb_sync_map() and viommu_flush_iotlb_all() need to
handle being called before the domain is finalized (for example by
iommu_create_device_direct_mappings()). In that case vdomain->viommu is
NULL so if you add a NULL check in viommu_sync_req() then you should be
able to drop the nr_endpoints checks in both patches.
Thanks,
Jean
> viommu_sync_req(vdomain->viommu);
> }
>
> +static int viommu_iotlb_sync_map(struct iommu_domain *domain,
> + unsigned long iova, size_t size)
> +{
> + struct viommu_domain *vdomain = to_viommu_domain(domain);
> +
> + if (!vdomain->nr_endpoints)
> + return 0;
> + return viommu_sync_req(vdomain->viommu);
> +}
> +
> static void viommu_get_resv_regions(struct device *dev, struct list_head *head)
> {
> struct iommu_resv_region *entry, *new_entry, *msi = NULL;
> @@ -1058,6 +1070,7 @@ static struct iommu_ops viommu_ops = {
> .unmap_pages = viommu_unmap_pages,
> .iova_to_phys = viommu_iova_to_phys,
> .iotlb_sync = viommu_iotlb_sync,
> + .iotlb_sync_map = viommu_iotlb_sync_map,
> .free = viommu_domain_free,
> }
> };
>
> --
> 2.39.2
>