Subject: [PATCH V6 3/5] iommu/dma-iommu: Handle deferred devices

From: Tom Murphy <[email-masked]>
Date: Sun, 8 Sep 2019 09:56:39 -0700

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

Signed-off-by: Tom Murphy <[email-masked]>
Reviewed-by: Robin Murphy <[email-masked]>
---
 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..bd09b6b31c4e 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 iommu_dma_deferred_attach(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(iommu_dma_deferred_attach(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);
@@ -581,6 +600,9 @@ static void *iommu_dma_alloc_remap(struct device *dev, size_t size,
 
 	*dma_handle = DMA_MAPPING_ERROR;
 
+	if (unlikely(iommu_dma_deferred_attach(dev, domain)))
+		return NULL;
+
 	min_size = alloc_sizes & -alloc_sizes;
 	if (min_size < PAGE_SIZE) {
 		min_size = PAGE_SIZE;
@@ -713,7 +735,7 @@ static dma_addr_t iommu_dma_map_page(struct device *dev, struct page *page,
 	int prot = dma_info_to_prot(dir, coherent, attrs);
 	dma_addr_t dma_handle;
 
-	dma_handle =__iommu_dma_map(dev, phys, size, prot);
+	dma_handle = __iommu_dma_map(dev, phys, size, prot);
 	if (!coherent && !(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
 	    dma_handle != DMA_MAPPING_ERROR)
 		arch_sync_dma_for_device(dev, phys, size, dir);
@@ -823,6 +845,9 @@ static int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg,
 	unsigned long mask = dma_get_seg_boundary(dev);
 	int i;
 
+	if (unlikely(iommu_dma_deferred_attach(dev, domain)))
+		return 0;
+
 	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
 		iommu_dma_sync_sg_for_device(dev, sg, nents, dir);
 
-- 
2.20.1

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