iommu/dma: Handle init_iova_flush_queue() failure in dma-iommu path

The init_iova_flush_queue() function can fail if we run out of memory. Fall
back to noflush queue if it fails.
Signed-off-by: Tom Murphy <murphyt7@tcd.ie>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/20200910122539.3662-1-murphyt7@tcd.ieSigned-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/dma-iommu.c

@@ -343,8 +343,11 @@ static int iommu_dma_init_domain(struct iommu_domain *domain, dma_addr_t base,
 
 	if (!cookie->fq_domain && !iommu_domain_get_attr(domain,
 			DOMAIN_ATTR_DMA_USE_FLUSH_QUEUE, &attr) && attr) {
-		cookie->fq_domain = domain;
-		init_iova_flush_queue(iovad, iommu_dma_flush_iotlb_all, NULL);
+		if (init_iova_flush_queue(iovad, iommu_dma_flush_iotlb_all,
+					NULL))
+			pr_warn("iova flush queue initialization failed\n");
+		else
+			cookie->fq_domain = domain;
 	}
 
 	if (!dev)