diff mbox

[v3,5/9] xen/gntdev: Allow mappings for DMA buffers

Message ID 20180612134200.17456-6-andr2000@gmail.com (mailing list archive)
State New, archived
Headers show

Commit Message

Oleksandr Andrushchenko June 12, 2018, 1:41 p.m. UTC 
From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>

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: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
---
 drivers/xen/gntdev.c      | 99 ++++++++++++++++++++++++++++++++++++++-
 include/uapi/xen/gntdev.h | 15 ++++++
 2 files changed, 112 insertions(+), 2 deletions(-)

Comments

Boris Ostrovsky June 13, 2018, 1:26 a.m. UTC | #1 
On 06/12/2018 09:41 AM, Oleksandr Andrushchenko wrote:

>   
>   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.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;


And again here.


> +		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 mfn;


This should be called bfn now.


> +
> +			mfn = pfn_to_bfn(page_to_pfn(map->pages[i]));
> +			map->unmap_ops[i].dev_bus_addr = __pfn_to_phys(mfn);
> +		}
> +#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 call of_dma_configure() with a NULL node to set


"Fix this by calling ..." I think.


> +	 * default DMA ops.
> +	 */
> +	of_dma_configure(priv->dma_dev, NULL);
> +#endif
>   	pr_debug("priv %p\n", priv);
>   
>   	return 0;


With those fixed,

Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Oleksandr Andrushchenko June 13, 2018, 7:16 a.m. UTC | #2 
On 06/13/2018 04:26 AM, Boris Ostrovsky wrote:
>
>
> On 06/12/2018 09:41 AM, Oleksandr Andrushchenko wrote:
>
>>     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.coherent = !!(map->dma_flags & GNTDEV_DMA_FLAG_COHERENT);
>
Will fix
>
>> +        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;
>
>
> And again here.
>
Will fix
>
>> +        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 mfn;
>
>
> This should be called bfn now.
>
Of course
>
>> +
>> +            mfn = pfn_to_bfn(page_to_pfn(map->pages[i]));
>> +            map->unmap_ops[i].dev_bus_addr = __pfn_to_phys(mfn);
>> +        }
>> +#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 call of_dma_configure() with a NULL node to set
>
>
> "Fix this by calling ..." I think.
>
Will fix
>
>> +     * default DMA ops.
>> +     */
>> +    of_dma_configure(priv->dma_dev, NULL);
>> +#endif
>>       pr_debug("priv %p\n", priv);
>>         return 0;
>
>
> With those fixed,
>
> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Thank you,
Oleksandr
Oleksandr Andrushchenko June 14, 2018, 7 a.m. UTC | #3 
@@ -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 call of_dma_configure() with a NULL node to set
> +	 * default DMA ops.
> +	 */
> +	of_dma_configure(priv->dma_dev, NULL);
Please note, that the code above will need a change while
applying to the mainline kernel because of API changes [1].
Unfortunately, current Xen tip kernel tree is v4.17-rc5 based,
so I cannot make the change in this patch now.

The change is trivial and requires:
-of_dma_configure(priv->dma_dev, NULL);
+of_dma_configure(priv->dma_dev, NULL, true);
> +#endif
>   	pr_debug("priv %p\n", priv);
>   
>   	return 0;
>
[1] 
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=3d6ce86ee79465e1b1b6e287f8ea26b553fc768e
diff mbox

Patch

diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index bd56653b9bbc..d6b79ad1cd6f 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -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 mfn;
+
+			mfn = pfn_to_bfn(page_to_pfn(map->pages[i]));
+			map->unmap_ops[i].dev_bus_addr = __pfn_to_phys(mfn);
+		}
+#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 call of_dma_configure() with a NULL node to set
+	 * default DMA ops.
+	 */
+	of_dma_configure(priv->dma_dev, NULL);
+#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;
 
diff --git a/include/uapi/xen/gntdev.h b/include/uapi/xen/gntdev.h
index 6d1163456c03..4b9d498a31d4 100644
--- a/include/uapi/xen/gntdev.h
+++ b/include/uapi/xen/gntdev.h
@@ -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__ */