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Commit 975ef7ff authored by Oleksandr Andrushchenko's avatar Oleksandr Andrushchenko Committed by Boris Ostrovsky
Browse files

xen/gntdev: Allow mappings for DMA buffers 



Allow mappings for DMA backed  buffers if grant table module
supports such: this extends grant device to not only map buffers
made of balloon pages, but also from buffers allocated with
dma_alloc_xxx.

Signed-off-by: default avatarOleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Reviewed-by: default avatarBoris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: default avatarBoris Ostrovsky <boris.ostrovsky@oracle.com>
parent 9bdc7304

drivers/xen/gntdev.c

+97 −2
Original line number Diff line number Diff line
@@ -37,6 +37,9 @@ 
#include <linux/slab.h>

#include <linux/highmem.h>

#include <linux/refcount.h>

#ifdef CONFIG_XEN_GRANT_DMA_ALLOC

#include <linux/of_device.h>

#endif



#include <xen/xen.h>

#include <xen/grant_table.h>
@@ -72,6 +75,11 @@ struct gntdev_priv { 
	struct mutex lock;

	struct mm_struct *mm;

	struct mmu_notifier mn;



#ifdef CONFIG_XEN_GRANT_DMA_ALLOC

	/* Device for which DMA memory is allocated. */

	struct device *dma_dev;

#endif

};



struct unmap_notify {
@@ -96,10 +104,27 @@ struct grant_map { 
	struct gnttab_unmap_grant_ref *kunmap_ops;

	struct page **pages;

	unsigned long pages_vm_start;



#ifdef CONFIG_XEN_GRANT_DMA_ALLOC

	/*

	 * If dmabuf_vaddr is not NULL then this mapping is backed by DMA

	 * capable memory.

	 */



	struct device *dma_dev;

	/* Flags used to create this DMA buffer: GNTDEV_DMA_FLAG_XXX. */

	int dma_flags;

	void *dma_vaddr;

	dma_addr_t dma_bus_addr;

	/* Needed to avoid allocation in gnttab_dma_free_pages(). */

	xen_pfn_t *frames;

#endif

};



static int unmap_grant_pages(struct grant_map *map, int offset, int pages);



static struct miscdevice gntdev_miscdev;



/* ------------------------------------------------------------------ */



static void gntdev_print_maps(struct gntdev_priv *priv,
@@ -121,8 +146,27 @@ static void gntdev_free_map(struct grant_map *map) 
	if (map == NULL)

		return;



#ifdef CONFIG_XEN_GRANT_DMA_ALLOC

	if (map->dma_vaddr) {

		struct gnttab_dma_alloc_args args;



		args.dev = map->dma_dev;

		args.coherent = !!(map->dma_flags & GNTDEV_DMA_FLAG_COHERENT);

		args.nr_pages = map->count;

		args.pages = map->pages;

		args.frames = map->frames;

		args.vaddr = map->dma_vaddr;

		args.dev_bus_addr = map->dma_bus_addr;



		gnttab_dma_free_pages(&args);

	} else

#endif

	if (map->pages)

		gnttab_free_pages(map->count, map->pages);



#ifdef CONFIG_XEN_GRANT_DMA_ALLOC

	kfree(map->frames);

#endif

	kfree(map->pages);

	kfree(map->grants);

	kfree(map->map_ops);
@@ -132,7 +176,8 @@ static void gntdev_free_map(struct grant_map *map) 
	kfree(map);

}



static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count)

static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count,

					  int dma_flags)

{

	struct grant_map *add;

	int i;
@@ -155,6 +200,37 @@ static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count) 
	    NULL == add->pages)

		goto err;



#ifdef CONFIG_XEN_GRANT_DMA_ALLOC

	add->dma_flags = dma_flags;



	/*

	 * Check if this mapping is requested to be backed

	 * by a DMA buffer.

	 */

	if (dma_flags & (GNTDEV_DMA_FLAG_WC | GNTDEV_DMA_FLAG_COHERENT)) {

		struct gnttab_dma_alloc_args args;



		add->frames = kcalloc(count, sizeof(add->frames[0]),

				      GFP_KERNEL);

		if (!add->frames)

			goto err;



		/* Remember the device, so we can free DMA memory. */

		add->dma_dev = priv->dma_dev;



		args.dev = priv->dma_dev;

		args.coherent = !!(dma_flags & GNTDEV_DMA_FLAG_COHERENT);

		args.nr_pages = count;

		args.pages = add->pages;

		args.frames = add->frames;



		if (gnttab_dma_alloc_pages(&args))

			goto err;



		add->dma_vaddr = args.vaddr;

		add->dma_bus_addr = args.dev_bus_addr;

	} else

#endif

	if (gnttab_alloc_pages(count, add->pages))

		goto err;
@@ -325,6 +401,14 @@ static int map_grant_pages(struct grant_map *map) 
		map->unmap_ops[i].handle = map->map_ops[i].handle;

		if (use_ptemod)

			map->kunmap_ops[i].handle = map->kmap_ops[i].handle;

#ifdef CONFIG_XEN_GRANT_DMA_ALLOC

		else if (map->dma_vaddr) {

			unsigned long bfn;



			bfn = pfn_to_bfn(page_to_pfn(map->pages[i]));

			map->unmap_ops[i].dev_bus_addr = __pfn_to_phys(bfn);

		}

#endif

	}

	return err;

}
@@ -548,6 +632,17 @@ static int gntdev_open(struct inode *inode, struct file *flip) 
	}



	flip->private_data = priv;

#ifdef CONFIG_XEN_GRANT_DMA_ALLOC

	priv->dma_dev = gntdev_miscdev.this_device;



	/*

	 * The device is not spawn from a device tree, so arch_setup_dma_ops

	 * is not called, thus leaving the device with dummy DMA ops.

	 * Fix this by calling of_dma_configure() with a NULL node to set

	 * default DMA ops.

	 */

	of_dma_configure(priv->dma_dev, NULL, true);

#endif

	pr_debug("priv %p\n", priv);



	return 0;
@@ -589,7 +684,7 @@ static long gntdev_ioctl_map_grant_ref(struct gntdev_priv *priv, 
		return -EINVAL;



	err = -ENOMEM;

	map = gntdev_alloc_map(priv, op.count);

	map = gntdev_alloc_map(priv, op.count, 0 /* This is not a dma-buf. */);

	if (!map)

		return err;

include/uapi/xen/gntdev.h

+15 −0
Original line number Diff line number Diff line
@@ -200,4 +200,19 @@ struct ioctl_gntdev_grant_copy { 
/* Send an interrupt on the indicated event channel */

#define UNMAP_NOTIFY_SEND_EVENT 0x2



/*

 * Flags to be used while requesting memory mapping's backing storage

 * to be allocated with DMA API.

 */



/*

 * The buffer is backed with memory allocated with dma_alloc_wc.

 */

#define GNTDEV_DMA_FLAG_WC		(1 << 0)



/*

 * The buffer is backed with memory allocated with dma_alloc_coherent.

 */

#define GNTDEV_DMA_FLAG_COHERENT	(1 << 1)



#endif /* __LINUX_PUBLIC_GNTDEV_H__ */