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Commit 975ef7ff authored by Oleksandr Andrushchenko's avatar Oleksandr Andrushchenko Committed by Boris Ostrovsky
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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
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+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;

+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__ */