[RFC PATCH v1 08/18] iommu/dma: Implement link/unlink ranges callbacks

[Leon Romanovsky <leon@kernel.org>]

From: Leon Romanovsky <leonro@nvidia.com>

Add an implementation of link/unlink interface to perform in map/unmap
pages in fast patch for pre-allocated IOVA.

Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
 drivers/iommu/dma-iommu.c | 79 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 79 insertions(+)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 0b5ca6961940..7425d155a14e 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -1731,6 +1731,82 @@ static void iommu_dma_free_iova(struct device *dev, dma_addr_t iova,
 	__iommu_dma_free_iova(cookie, iova, size, &iotlb_gather);
 }
 
+static int iommu_dma_start_range(struct dma_iova_state *state)
+{
+	struct device *dev = state->iova->dev;
+
+	state->domain = iommu_get_dma_domain(dev);
+
+	if (static_branch_unlikely(&iommu_deferred_attach_enabled))
+		return iommu_deferred_attach(dev, state->domain);
+
+	return 0;
+}
+
+static int iommu_dma_link_range(struct dma_iova_state *state, phys_addr_t phys,
+				dma_addr_t addr, size_t size)
+{
+	struct iommu_domain *domain = state->domain;
+	struct iommu_dma_cookie *cookie = domain->iova_cookie;
+	struct iova_domain *iovad = &cookie->iovad;
+	struct device *dev = state->iova->dev;
+	enum dma_data_direction dir = state->iova->dir;
+	bool coherent = dev_is_dma_coherent(dev);
+	unsigned long attrs = state->iova->attrs;
+	int prot = dma_info_to_prot(dir, coherent, attrs);
+
+	if (!coherent && !(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+		arch_sync_dma_for_device(phys, size, dir);
+
+	size = iova_align(iovad, size);
+	return iommu_map(domain, addr, phys, size, prot, GFP_ATOMIC);
+}
+
+static void iommu_sync_dma_for_cpu(struct iommu_domain *domain,
+				   dma_addr_t start, size_t size,
+				   enum dma_data_direction dir)
+{
+	size_t sync_size, unmapped = 0;
+	phys_addr_t phys;
+
+	do {
+		phys = iommu_iova_to_phys(domain, start + unmapped);
+		if (WARN_ON(!phys))
+			continue;
+
+		sync_size = (unmapped + PAGE_SIZE > size) ? size % PAGE_SIZE :
+							    PAGE_SIZE;
+		arch_sync_dma_for_cpu(phys, sync_size, dir);
+		unmapped += sync_size;
+	} while (unmapped < size);
+}
+
+static void iommu_dma_unlink_range(struct dma_iova_state *state,
+				   dma_addr_t start, size_t size)
+{
+	struct device *dev = state->iova->dev;
+	struct iommu_domain *domain = iommu_get_dma_domain(dev);
+	struct iommu_dma_cookie *cookie = domain->iova_cookie;
+	struct iova_domain *iovad = &cookie->iovad;
+	struct iommu_iotlb_gather iotlb_gather;
+	bool coherent = dev_is_dma_coherent(dev);
+	unsigned long attrs = state->iova->attrs;
+	size_t unmapped;
+
+	iommu_iotlb_gather_init(&iotlb_gather);
+	iotlb_gather.queued = READ_ONCE(cookie->fq_domain);
+
+	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) && !coherent)
+		iommu_sync_dma_for_cpu(domain, start, size, state->iova->dir);
+
+	size = iova_align(iovad, size);
+	unmapped = iommu_unmap_fast(domain, start, size, &iotlb_gather);
+	WARN_ON(unmapped != size);
+
+	if (!iotlb_gather.queued)
+		iommu_iotlb_sync(domain, &iotlb_gather);
+}
+
 static const struct dma_map_ops iommu_dma_ops = {
 	.flags			= DMA_F_PCI_P2PDMA_SUPPORTED |
 				  DMA_F_CAN_SKIP_SYNC,
@@ -1757,6 +1833,9 @@ static const struct dma_map_ops iommu_dma_ops = {
 	.max_mapping_size       = iommu_dma_max_mapping_size,
 	.alloc_iova		= iommu_dma_alloc_iova,
 	.free_iova		= iommu_dma_free_iova,
+	.link_range		= iommu_dma_link_range,
+	.unlink_range		= iommu_dma_unlink_range,
+	.start_range		= iommu_dma_start_range,
 };
 
 void iommu_setup_dma_ops(struct device *dev)
-- 
2.45.2