linux-kernel - [Xen-devel][RFC 2/3] xen/grant-table: Extend API to work with DMA buffers

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Date:   Thu, 17 May 2018 11:26:03 +0300
From:   Oleksandr Andrushchenko <andr2000@...il.com>
To:     xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, linux-media@...r.kernel.org,
        jgross@...e.com, boris.ostrovsky@...cle.com, konrad.wilk@...cle.com
Cc:     daniel.vetter@...el.com, andr2000@...il.com, dongwon.kim@...el.com,
        matthew.d.roper@...el.com,
        Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>
Subject: [Xen-devel][RFC 2/3] xen/grant-table: Extend API to work with DMA buffers

From: Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>

Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>
---
 drivers/xen/grant-table.c | 49 +++++++++++++++++++++++++++++++++++++++
 include/xen/grant_table.h |  7 ++++++
 2 files changed, 56 insertions(+)

diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
index bb36b1e1dbcc..c27bcc420575 100644
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -729,6 +729,55 @@ void gnttab_free_pages(int nr_pages, struct page **pages)
 }
 EXPORT_SYMBOL(gnttab_free_pages);
 
+int gnttab_dma_alloc_pages(struct device *dev, bool coherent,
+			   int nr_pages, struct page **pages,
+			   void **vaddr, dma_addr_t *dev_bus_addr)
+{
+	int i;
+	int ret;
+
+	ret = alloc_dma_xenballooned_pages(dev, coherent, nr_pages, pages,
+					   vaddr, dev_bus_addr);
+	if (ret < 0)
+		return ret;
+
+	for (i = 0; i < nr_pages; i++) {
+#if BITS_PER_LONG < 64
+		struct xen_page_foreign *foreign;
+
+		foreign = kzalloc(sizeof(*foreign), GFP_KERNEL);
+		if (!foreign) {
+			gnttab_dma_free_pages(dev, flags, nr_pages, pages,
+					      *vaddr, *dev_bus_addr);
+			return -ENOMEM;
+		}
+		set_page_private(pages[i], (unsigned long)foreign);
+#endif
+		SetPagePrivate(pages[i]);
+	}
+	return 0;
+}
+EXPORT_SYMBOL(gnttab_dma_alloc_pages);
+
+void gnttab_dma_free_pages(struct device *dev, bool coherent,
+			   int nr_pages, struct page **pages,
+			   void *vaddr, dma_addr_t dev_bus_addr)
+{
+	int i;
+
+	for (i = 0; i < nr_pages; i++) {
+		if (PagePrivate(pages[i])) {
+#if BITS_PER_LONG < 64
+			kfree((void *)page_private(pages[i]));
+#endif
+			ClearPagePrivate(pages[i]);
+		}
+	}
+	free_dma_xenballooned_pages(dev, coherent, nr_pages, pages,
+				    vaddr, dev_bus_addr);
+}
+EXPORT_SYMBOL(gnttab_dma_free_pages);
+
 /* Handling of paged out grant targets (GNTST_eagain) */
 #define MAX_DELAY 256
 static inline void
diff --git a/include/xen/grant_table.h b/include/xen/grant_table.h
index 34b1379f9777..20ee2b5ba965 100644
--- a/include/xen/grant_table.h
+++ b/include/xen/grant_table.h
@@ -195,6 +195,13 @@ void gnttab_free_auto_xlat_frames(void);
 int gnttab_alloc_pages(int nr_pages, struct page **pages);
 void gnttab_free_pages(int nr_pages, struct page **pages);
 
+int gnttab_dma_alloc_pages(struct device *dev, bool coherent,
+			   int nr_pages, struct page **pages,
+			   void **vaddr, dma_addr_t *dev_bus_addr);
+void gnttab_dma_free_pages(struct device *dev, bool coherent,
+			   int nr_pages, struct page **pages,
+			   void *vaddr, dma_addr_t dev_bus_addr);
+
 int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
 		    struct gnttab_map_grant_ref *kmap_ops,
 		    struct page **pages, unsigned int count);
-- 
2.17.0