[PATCH V2 2/6] dma-mapping: Add vmap/vunmap_noncontiguous() callback in dma ops

From: Tianyu Lan <ltykernel@gmail.com>
To: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
	dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com,
	luto@kernel.org, peterz@infradead.org, jgross@suse.com,
	sstabellini@kernel.org, boris.ostrovsky@oracle.com,
	kys@microsoft.com, haiyangz@microsoft.com,
	sthemmin@microsoft.com, wei.liu@kernel.org, decui@microsoft.com,
	joro@8bytes.org, will@kernel.org, davem@davemloft.net,
	kuba@kernel.org, jejb@linux.ibm.com, martin.petersen@oracle.com,
	hch@lst.de, m.szyprowski@samsung.com, robin.murphy@arm.com,
	Tianyu.Lan@microsoft.com, thomas.lendacky@amd.com,
	xen-devel@lists.xenproject.org, michael.h.kelley@microsoft.com
Cc: iommu@lists.linux-foundation.org, linux-hyperv@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org,
	netdev@vger.kernel.org, vkuznets@redhat.com,
	brijesh.singh@amd.com, konrad.wilk@oracle.com,
	parri.andrea@gmail.com, dave.hansen@intel.com
Subject: [PATCH V2 2/6] dma-mapping: Add vmap/vunmap_noncontiguous() callback in dma ops
Date: Tue, 23 Nov 2021 09:30:33 -0500	[thread overview]
Message-ID: <20211123143039.331929-3-ltykernel@gmail.com> (raw)
In-Reply-To: <20211123143039.331929-1-ltykernel@gmail.com>

From: Tianyu Lan <Tianyu.Lan@microsoft.com>

Hyper-V netvsc driver needs to allocate noncontiguous DMA memory and
remap it into unencrypted address space before sharing with host. Add
vmap/vunmap_noncontiguous() callback and handle the remap in the Hyper-V
dma ops callback.

Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
---
 include/linux/dma-map-ops.h |  3 +++
 kernel/dma/mapping.c        | 18 ++++++++++++++----
 2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/include/linux/dma-map-ops.h b/include/linux/dma-map-ops.h
index 0d5b06b3a4a6..f7b9958ca20a 100644
--- a/include/linux/dma-map-ops.h
+++ b/include/linux/dma-map-ops.h
@@ -27,6 +27,9 @@ struct dma_map_ops {
 			unsigned long attrs);
 	void (*free_noncontiguous)(struct device *dev, size_t size,
 			struct sg_table *sgt, enum dma_data_direction dir);
+	void *(*vmap_noncontiguous)(struct device *dev, size_t size,
+			struct sg_table *sgt);
+	void (*vunmap_noncontiguous)(struct device *dev, void *addr);
 	int (*mmap)(struct device *, struct vm_area_struct *,
 			void *, dma_addr_t, size_t, unsigned long attrs);
 
diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c
index 9478eccd1c8e..7fd751d866cc 100644
--- a/kernel/dma/mapping.c
+++ b/kernel/dma/mapping.c
@@ -674,8 +674,14 @@ void *dma_vmap_noncontiguous(struct device *dev, size_t size,
 	const struct dma_map_ops *ops = get_dma_ops(dev);
 	unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
 
-	if (ops && ops->alloc_noncontiguous)
-		return vmap(sgt_handle(sgt)->pages, count, VM_MAP, PAGE_KERNEL);
+	if (ops) {
+		if (ops->vmap_noncontiguous)
+			return ops->vmap_noncontiguous(dev, size, sgt);
+		else if (ops->alloc_noncontiguous)
+			return vmap(sgt_handle(sgt)->pages, count, VM_MAP,
+				    PAGE_KERNEL);
+	}
+
 	return page_address(sg_page(sgt->sgl));
 }
 EXPORT_SYMBOL_GPL(dma_vmap_noncontiguous);
@@ -684,8 +690,12 @@ void dma_vunmap_noncontiguous(struct device *dev, void *vaddr)
 {
 	const struct dma_map_ops *ops = get_dma_ops(dev);
 
-	if (ops && ops->alloc_noncontiguous)
-		vunmap(vaddr);
+	if (ops) {
+		if (ops->vunmap_noncontiguous)
+			ops->vunmap_noncontiguous(dev, vaddr);
+		else if (ops->alloc_noncontiguous)
+			vunmap(vaddr);
+	}
 }
 EXPORT_SYMBOL_GPL(dma_vunmap_noncontiguous);
 
-- 
2.25.1

