Re: [PATCH V5 3/5] iommu/dma-iommu: Handle deferred devices

Handle devices which defer their attach to the iommu in the dma-iommu api

Signed-off-by: Tom Murphy <redacted>
---
 drivers/iommu/dma-iommu.c | 27 ++++++++++++++++++++++++++-
 1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 2712fbc68b28..906b7fa14d3c 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c

@@ -22,6 +22,7 @@
 #include <linux/pci.h>
 #include <linux/scatterlist.h>
 #include <linux/vmalloc.h>
+#include <linux/crash_dump.h>
 
 struct iommu_dma_msi_page {
 	struct list_head	list;

@@ -351,6 +352,21 @@ static int iommu_dma_init_domain(struct iommu_domain *domain, dma_addr_t base,
 	return iova_reserve_iommu_regions(dev, domain);
 }
 
+static int handle_deferred_device(struct device *dev,
+	struct iommu_domain *domain)
+{
+	const struct iommu_ops *ops = domain->ops;
+
+	if (!is_kdump_kernel())
+		return 0;
+
+	if (unlikely(ops->is_attach_deferred &&
+		ops->is_attach_deferred(domain, dev)))
+		return iommu_attach_device(domain, dev);
+
+	return 0;
+}
+
 /**
  * dma_info_to_prot - Translate DMA API directions and attributes to IOMMU API
  *                    page flags.

@@ -463,6 +479,9 @@ static dma_addr_t __iommu_dma_map(struct device *dev, phys_addr_t phys,
 	size_t iova_off = iova_offset(iovad, phys);
 	dma_addr_t iova;
 
+	if (unlikely(handle_deferred_device(dev, domain)))
+		return DMA_MAPPING_ERROR;
+
 	size = iova_align(iovad, size + iova_off);
 
 	iova = iommu_dma_alloc_iova(domain, size, dma_get_mask(dev), dev);