linux-kernel - [PATCH 2/5] dma-mapping: Add vmap/vunmap

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Message-Id: <20211116153923.196763-3-ltykernel@gmail.com>
Date:   Tue, 16 Nov 2021 10:39:20 -0500
From:   Tianyu Lan <ltykernel@...il.com>
To:     dave.hansen@...ux.intel.com, luto@...nel.org, peterz@...radead.org,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, x86@...nel.org,
        hpa@...or.com, jgross@...e.com, sstabellini@...nel.org,
        boris.ostrovsky@...cle.com, kys@...rosoft.com,
        haiyangz@...rosoft.com, sthemmin@...rosoft.com, wei.liu@...nel.org,
        decui@...rosoft.com, joro@...tes.org, will@...nel.org,
        davem@...emloft.net, kuba@...nel.org, jejb@...ux.ibm.com,
        martin.petersen@...cle.com, hch@....de, m.szyprowski@...sung.com,
        robin.murphy@....com, xen-devel@...ts.xenproject.org,
        michael.h.kelley@...rosoft.com
Cc:     Tianyu Lan <Tianyu.Lan@...rosoft.com>,
        iommu@...ts.linux-foundation.org, linux-hyperv@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-scsi@...r.kernel.org,
        netdev@...r.kernel.org, vkuznets@...hat.com, brijesh.singh@....com,
        konrad.wilk@...cle.com, parri.andrea@...il.com,
        thomas.lendacky@....com, dave.hansen@...el.com
Subject: [PATCH 2/5] dma-mapping: Add vmap/vunmap_noncontiguous() callback in dma ops

From: Tianyu Lan <Tianyu.Lan@...rosoft.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@...rosoft.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