[RFC v2 03/21] iommu/dma: Add check if IOVA can be used

[Leon Romanovsky]

From: Leon Romanovsky <leonro at nvidia.com>

This patch adds a check if IOVA can be used for the page and size.

Signed-off-by: Leon Romanovsky <leonro at nvidia.com>
---
 drivers/iommu/dma-iommu.c   | 21 +++++++++++++++++++++
 drivers/pci/p2pdma.c        |  4 ++--
 include/linux/dma-map-ops.h |  7 +++++++
 include/linux/iommu-dma.h   |  7 +++++++
 4 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 72763f76b712..3e2e382bb502 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -11,6 +11,7 @@
 #include <linux/acpi_iort.h>
 #include <linux/atomic.h>
 #include <linux/crash_dump.h>
+#include <linux/cc_platform.h>
 #include <linux/device.h>
 #include <linux/dma-direct.h>
 #include <linux/dma-map-ops.h>
@@ -1829,6 +1830,26 @@ void iommu_dma_unlink_range(struct device *dev, dma_addr_t start, size_t size,
 		iommu_iotlb_sync(domain, &iotlb_gather);
 }
 
+bool iommu_can_use_iova(struct device *dev, struct page *page, size_t size,
+			enum dma_data_direction dir)
+{
+	enum pci_p2pdma_map_type map;
+
+	if (is_swiotlb_force_bounce(dev) || dev_use_swiotlb(dev, size, dir))
+		return false;
+
+	/* TODO: Rewrite this check to rely on specific struct page flags */
+	if (cc_platform_has(CC_ATTR_MEM_ENCRYPT))
+		return false;
+
+	if (page && is_pci_p2pdma_page(page)) {
+		map = pci_p2pdma_map_type(page->pgmap, dev);
+		return map == PCI_P2PDMA_MAP_THRU_HOST_BRIDGE;
+	}
+
+	return true;
+}
+
 void iommu_setup_dma_ops(struct device *dev)
 {
 	struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c
index 4f47a13cb500..6ceea32bb041 100644
--- a/drivers/pci/p2pdma.c
+++ b/drivers/pci/p2pdma.c
@@ -964,8 +964,8 @@ void pci_p2pmem_publish(struct pci_dev *pdev, bool publish)
 }
 EXPORT_SYMBOL_GPL(pci_p2pmem_publish);
 
-static enum pci_p2pdma_map_type pci_p2pdma_map_type(struct dev_pagemap *pgmap,
-						    struct device *dev)
+enum pci_p2pdma_map_type pci_p2pdma_map_type(struct dev_pagemap *pgmap,
+					     struct device *dev)
 {
 	enum pci_p2pdma_map_type type = PCI_P2PDMA_MAP_NOT_SUPPORTED;
 	struct pci_dev *provider = to_p2p_pgmap(pgmap)->provider;
diff --git a/include/linux/dma-map-ops.h b/include/linux/dma-map-ops.h
index 103d9c66c445..936e822e9f40 100644
--- a/include/linux/dma-map-ops.h
+++ b/include/linux/dma-map-ops.h
@@ -516,6 +516,8 @@ struct pci_p2pdma_map_state {
 enum pci_p2pdma_map_type
 pci_p2pdma_map_segment(struct pci_p2pdma_map_state *state, struct device *dev,
 		       struct scatterlist *sg);
+enum pci_p2pdma_map_type pci_p2pdma_map_type(struct dev_pagemap *pgmap,
+					     struct device *dev);
 #else /* CONFIG_PCI_P2PDMA */
 static inline enum pci_p2pdma_map_type
 pci_p2pdma_map_segment(struct pci_p2pdma_map_state *state, struct device *dev,
@@ -523,6 +525,11 @@ pci_p2pdma_map_segment(struct pci_p2pdma_map_state *state, struct device *dev,
 {
 	return PCI_P2PDMA_MAP_NOT_SUPPORTED;
 }
+static inline enum pci_p2pdma_map_type
+pci_p2pdma_map_type(struct dev_pagemap *pgmap, struct device *dev)
+{
+	return PCI_P2PDMA_MAP_NOT_SUPPORTED;
+}
 #endif /* CONFIG_PCI_P2PDMA */
 
 #endif /* _LINUX_DMA_MAP_OPS_H */
diff --git a/include/linux/iommu-dma.h b/include/linux/iommu-dma.h
index 21b0341f52b8..561d81b12d9c 100644
--- a/include/linux/iommu-dma.h
+++ b/include/linux/iommu-dma.h
@@ -66,6 +66,8 @@ dma_addr_t iommu_dma_link_range(struct dma_iova_state *state, phys_addr_t phys,
 				size_t size, unsigned long attrs);
 void iommu_dma_unlink_range(struct device *dev, dma_addr_t start, size_t size,
 			    enum dma_data_direction dir, unsigned long attrs);
+bool iommu_can_use_iova(struct device *dev, struct page *page, size_t size,
+			enum dma_data_direction dir);
 #else
 static inline bool use_dma_iommu(struct device *dev)
 {
@@ -209,5 +211,10 @@ static inline void iommu_dma_unlink_range(struct device *dev, dma_addr_t start,
 					  unsigned long attrs)
 {
 }
+static inline bool iommu_can_use_iova(struct device *dev, struct page *page,
+				      size_t size, enum dma_data_direction dir)
+{
+	return false;
+}
 #endif /* CONFIG_IOMMU_DMA */
 #endif /* _LINUX_IOMMU_DMA_H */
-- 
2.46.0