Factor out flush queue setup from the initial domain init so that we
can potentially trigger it from sysfs later on in a domain's lifetime.

Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: John Garry <redacted>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
---
 drivers/iommu/dma-iommu.c | 30 ++++++++++++++++++++----------
 include/linux/dma-iommu.h |  9 ++++++---
 2 files changed, 26 insertions(+), 13 deletions(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 2e19505dddf9..f51b8dc99ac6 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c

@@ -310,6 +310,25 @@ static bool dev_is_untrusted(struct device *dev)
 	return dev_is_pci(dev) && to_pci_dev(dev)->untrusted;
 }
 
+int iommu_dma_init_fq(struct iommu_domain *domain)
+{
+	struct iommu_dma_cookie *cookie = domain->iova_cookie;
+
+	if (domain->type != IOMMU_DOMAIN_DMA_FQ)
+		return -EINVAL;
+	if (cookie->fq_domain)
+		return 0;
+
+	if (init_iova_flush_queue(&cookie->iovad, iommu_dma_flush_iotlb_all,
+				  iommu_dma_entry_dtor)) {
+		pr_warn("iova flush queue initialization failed\n");
+		domain->type = IOMMU_DOMAIN_DMA;
+		return -ENODEV;