[RFC 0/4] Separate the IOVA library from the intel-iommu driver

[RFC 0/4] Separate the IOVA library from the intel-iommu driver

[Sakari Ailus]

Hi,

This set separates the IOVA library from the intel-iommu driver, and makes
it usable for other implementations (such as DMA mapping) as well.

While I don't have a DMA mapping implementation to share at the moment, the
patches might be useful for the others in the meantime and I wouldn't mind
having them in upstream either.

-- 
Kind regards,
Sakari

[RFC 1/4] iommu: iova: Move iova cache management to the iova library

[Sakari Ailus]

alloc_iova_mem() and free_iova_mem() are moved to iova.c and made static as
well. printk(KERN_ERR, ...) is also replaced by pr_err().

This is done in order to separate intel-iommu from the iova library. As a
result, the user of the IOVA library must use iova_cache_get() before using
alloc_iova_mem() or free_iova_mem(), and correspondingly iova_cache_put()
after using the IOVA library.

Signed-off-by: Sakari Ailus <sakari.ailus-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
---
 drivers/iommu/intel-iommu.c | 34 +++-----------------------------
 drivers/iommu/iova.c        | 48 +++++++++++++++++++++++++++++++++++++++++++++
 include/linux/iova.h        |  4 ++--
 3 files changed, 53 insertions(+), 33 deletions(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index a27d6cb..e7673df 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -490,7 +490,6 @@ __setup("intel_iommu=", intel_iommu_setup);
 
 static struct kmem_cache *iommu_domain_cache;
 static struct kmem_cache *iommu_devinfo_cache;
-static struct kmem_cache *iommu_iova_cache;
 
 static inline void *alloc_pgtable_page(int node)
 {
@@ -528,16 +527,6 @@ static inline void free_devinfo_mem(void *vaddr)
 	kmem_cache_free(iommu_devinfo_cache, vaddr);
 }
 
-struct iova *alloc_iova_mem(void)
-{
-	return kmem_cache_alloc(iommu_iova_cache, GFP_ATOMIC);
-}
-
-void free_iova_mem(struct iova *iova)
-{
-	kmem_cache_free(iommu_iova_cache, iova);
-}
-
 static inline int domain_type_is_vm(struct dmar_domain *domain)
 {
 	return domain->flags & DOMAIN_FLAG_VIRTUAL_MACHINE;
@@ -3429,27 +3418,10 @@ static inline int iommu_devinfo_cache_init(void)
 	return ret;
 }
 
-static inline int iommu_iova_cache_init(void)
-{
-	int ret = 0;
-
-	iommu_iova_cache = kmem_cache_create("iommu_iova",
-					 sizeof(struct iova),
-					 0,
-					 SLAB_HWCACHE_ALIGN,
-					 NULL);
-	if (!iommu_iova_cache) {
-		printk(KERN_ERR "Couldn't create iova cache\n");
-		ret = -ENOMEM;
-	}
-
-	return ret;
-}
-
 static int __init iommu_init_mempool(void)
 {
 	int ret;
-	ret = iommu_iova_cache_init();
+	ret = iova_cache_get();
 	if (ret)
 		return ret;
 
@@ -3463,7 +3435,7 @@ static int __init iommu_init_mempool(void)
 
 	kmem_cache_destroy(iommu_domain_cache);
 domain_error:
-	kmem_cache_destroy(iommu_iova_cache);
+	iova_cache_put();
 
 	return -ENOMEM;
 }
@@ -3472,7 +3444,7 @@ static void __init iommu_exit_mempool(void)
 {
 	kmem_cache_destroy(iommu_devinfo_cache);
 	kmem_cache_destroy(iommu_domain_cache);
-	kmem_cache_destroy(iommu_iova_cache);
+	iova_cache_put();
 
 }
 
diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c
index f6b17e6..6bc7022 100644
--- a/drivers/iommu/iova.c
+++ b/drivers/iommu/iova.c
@@ -18,6 +18,7 @@
  */
 
 #include <linux/iova.h>
+#include <linux/slab.h>
 
 void
 init_iova_domain(struct iova_domain *iovad, unsigned long pfn_32bit)
@@ -196,6 +197,53 @@ iova_insert_rbtree(struct rb_root *root, struct iova *iova)
 	rb_insert_color(&iova->node, root);
 }
 
+static struct kmem_cache *iova_cache;
+static unsigned int iova_cache_users;
+static DEFINE_MUTEX(iova_cache_mutex);
+
+static struct iova *alloc_iova_mem(void)
+{
+	return kmem_cache_alloc(iova_cache, GFP_ATOMIC);
+}
+
+static void free_iova_mem(struct iova *iova)
+{
+	kmem_cache_free(iova_cache, iova);
+}
+
+int iova_cache_get(void)
+{
+	mutex_lock(&iova_cache_mutex);
+	if (!iova_cache_users) {
+		iova_cache = kmem_cache_create(
+			"iommu_iova", sizeof(struct iova), 0,
+			SLAB_HWCACHE_ALIGN, NULL);
+		if (!iova_cache) {
+			mutex_unlock(&iova_cache_mutex);
+			pr_err("Couldn't create iova cache\n");
+			return -ENOMEM;
+		}
+	}
+
+	iova_cache_users++;
+	mutex_unlock(&iova_cache_mutex);
+
+	return 0;
+}
+
+void iova_cache_put(void)
+{
+	mutex_lock(&iova_cache_mutex);
+	if (WARN_ON(!iova_cache_users)) {
+		mutex_unlock(&iova_cache_mutex);
+		return;
+	}
+	iova_cache_users--;
+	if (!iova_cache_users)
+		kmem_cache_destroy(iova_cache);
+	mutex_unlock(&iova_cache_mutex);
+}
+
 /**
  * alloc_iova - allocates an iova
  * @iovad: - iova domain in question
diff --git a/include/linux/iova.h b/include/linux/iova.h
index 19e81d5..8572031 100644
--- a/include/linux/iova.h
+++ b/include/linux/iova.h
@@ -39,8 +39,8 @@ static inline unsigned long iova_size(struct iova *iova)
 	return iova->pfn_hi - iova->pfn_lo + 1;
 }
 
-struct iova *alloc_iova_mem(void);
-void free_iova_mem(struct iova *iova);
+int iova_cache_get(void);
+void iova_cache_put(void);
 void free_iova(struct iova_domain *iovad, unsigned long pfn);
 void __free_iova(struct iova_domain *iovad, struct iova *iova);
 struct iova *alloc_iova(struct iova_domain *iovad, unsigned long size,
-- 
2.1.0.231.g7484e3b

[RFC 2/4] iommu: iova: Export symbols

[Sakari Ailus]

Use EXPORT_SYMBOL_GPL() to export the iova library symbols. The symbols
include:

	init_iova_domain();
	iova_cache_get();
	iova_cache_put();
	alloc_iova();
	find_iova();
	__free_iova();
	free_iova();
	put_iova_domain();
	reserve_iova();

This is necessary in order to use the iova library from a kernel module.

Signed-off-by: Sakari Ailus <sakari.ailus-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
---
 drivers/iommu/iova.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c
index 6bc7022..e9e62f4 100644
--- a/drivers/iommu/iova.c
+++ b/drivers/iommu/iova.c
@@ -28,6 +28,7 @@ init_iova_domain(struct iova_domain *iovad, unsigned long pfn_32bit)
 	iovad->cached32_node = NULL;
 	iovad->dma_32bit_pfn = pfn_32bit;
 }
+EXPORT_SYMBOL_GPL(init_iova_domain);
 
 static struct rb_node *
 __get_cached_rbnode(struct iova_domain *iovad, unsigned long *limit_pfn)
@@ -230,6 +231,7 @@ int iova_cache_get(void)
 
 	return 0;
 }
+EXPORT_SYMBOL_GPL(iova_cache_get);
 
 void iova_cache_put(void)
 {
@@ -243,6 +245,7 @@ void iova_cache_put(void)
 		kmem_cache_destroy(iova_cache);
 	mutex_unlock(&iova_cache_mutex);
 }
+EXPORT_SYMBOL_GPL(iova_cache_put);
 
 /**
  * alloc_iova - allocates an iova
@@ -283,6 +286,7 @@ alloc_iova(struct iova_domain *iovad, unsigned long size,
 
 	return new_iova;
 }
+EXPORT_SYMBOL_GPL(alloc_iova);
 
 /**
  * find_iova - find's an iova for a given pfn
@@ -323,6 +327,7 @@ struct iova *find_iova(struct iova_domain *iovad, unsigned long pfn)
 	spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
 	return NULL;
 }
+EXPORT_SYMBOL_GPL(find_iova);
 
 /**
  * __free_iova - frees the given iova
@@ -341,6 +346,7 @@ __free_iova(struct iova_domain *iovad, struct iova *iova)
 	spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
 	free_iova_mem(iova);
 }
+EXPORT_SYMBOL_GPL(__free_iova);
 
 /**
  * free_iova - finds and frees the iova for a given pfn
@@ -357,6 +363,7 @@ free_iova(struct iova_domain *iovad, unsigned long pfn)
 		__free_iova(iovad, iova);
 
 }
+EXPORT_SYMBOL_GPL(free_iova);
 
 /**
  * put_iova_domain - destroys the iova doamin
@@ -378,6 +385,7 @@ void put_iova_domain(struct iova_domain *iovad)
 	}
 	spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
 }
+EXPORT_SYMBOL_GPL(put_iova_domain);
 
 static int
 __is_range_overlap(struct rb_node *node,
@@ -467,6 +475,7 @@ finish:
 	spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
 	return iova;
 }
+EXPORT_SYMBOL_GPL(reserve_iova);
 
 /**
  * copy_reserved_iova - copies the reserved between domains
-- 
2.1.0.231.g7484e3b

[RFC 3/4] iommu: iova: Make the iova library buildable as a module

[Sakari Ailus]

The iova library is usable elsewhere than just the intel-iommu driver, thus
make it also buildable a module.

Signed-off-by: Sakari Ailus <sakari.ailus-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
---
 drivers/iommu/Kconfig  | 4 ++++
 drivers/iommu/Makefile | 3 ++-
 drivers/iommu/iova.c   | 4 ++++
 3 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index dd51122..b139748 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -87,11 +87,15 @@ config AMD_IOMMU_V2
 config DMAR_TABLE
 	bool
 
+config IOMMU_IOVA
+	tristate
+
 config INTEL_IOMMU
 	bool "Support for Intel IOMMU using DMA Remapping Devices"
 	depends on PCI_MSI && ACPI && (X86 || IA64_GENERIC)
 	select IOMMU_API
 	select DMAR_TABLE
+	select IOMMU_IOVA
 	help
 	  DMA remapping (DMAR) devices support enables independent address
 	  translations for Direct Memory Access (DMA) from devices.
diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
index 16edef7..66668a6 100644
--- a/drivers/iommu/Makefile
+++ b/drivers/iommu/Makefile
@@ -7,7 +7,8 @@ obj-$(CONFIG_AMD_IOMMU) += amd_iommu.o amd_iommu_init.o
 obj-$(CONFIG_AMD_IOMMU_V2) += amd_iommu_v2.o
 obj-$(CONFIG_ARM_SMMU) += arm-smmu.o
 obj-$(CONFIG_DMAR_TABLE) += dmar.o
-obj-$(CONFIG_INTEL_IOMMU) += iova.o intel-iommu.o
+obj-$(CONFIG_INTEL_IOMMU) += intel-iommu.o
+obj-$(CONFIG_IOMMU_IOVA) += iova.o
 obj-$(CONFIG_IPMMU_VMSA) += ipmmu-vmsa.o
 obj-$(CONFIG_IRQ_REMAP) += intel_irq_remapping.o irq_remapping.o
 obj-$(CONFIG_OMAP_IOMMU) += omap-iommu.o
diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c
index e9e62f4..c9142b2 100644
--- a/drivers/iommu/iova.c
+++ b/drivers/iommu/iova.c
@@ -18,6 +18,7 @@
  */
 
 #include <linux/iova.h>
+#include <linux/module.h>
 #include <linux/slab.h>
 
 void
@@ -542,3 +543,6 @@ error:
 		free_iova_mem(prev);
 	return NULL;
 }
+
+MODULE_AUTHOR("Anil S Keshavamurthy <anil.s.keshavamurthy-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>");
+MODULE_LICENSE("GPL");
-- 
2.1.0.231.g7484e3b

[RFC 4/4] mm: EXPORT_SYMBOL_GPL({find_vm_area,get_vm_area_caller});

[Sakari Ailus]

These APIs are needed in DMA mapping API implementation as a module. Device
specific IOMMUs with associated DMA mapping implementations should be
buildable as modules.

Signed-off-by: Sakari Ailus <sakari.ailus-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
---
 mm/vmalloc.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 90520af..f22c01c 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1379,6 +1379,7 @@ struct vm_struct *get_vm_area_caller(unsigned long size, unsigned long flags,
 	return __get_vm_area_node(size, 1, flags, VMALLOC_START, VMALLOC_END,
 				  NUMA_NO_NODE, GFP_KERNEL, caller);
 }
+EXPORT_SYMBOL_GPL(get_vm_area_caller);
 
 /**
  *	find_vm_area  -  find a continuous kernel virtual area
@@ -1398,6 +1399,7 @@ struct vm_struct *find_vm_area(const void *addr)
 
 	return NULL;
 }
+EXPORT_SYMBOL_GPL(find_vm_area);
 
 /**
  *	remove_vm_area  -  find and remove a continuous kernel virtual area
-- 
2.1.0.231.g7484e3b

Re: [RFC 0/4] Separate the IOVA library from the intel-iommu driver

[David Woodhouse]

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On Fri, 2014-11-21 at 13:11 +0200, Sakari Ailus wrote:
> Hi,
> 
> This set separates the IOVA library from the intel-iommu driver, and makes
> it usable for other implementations (such as DMA mapping) as well.
> 
> While I don't have a DMA mapping implementation to share at the moment, the
> patches might be useful for the others in the meantime and I wouldn't mind
> having them in upstream either.

Acked-By: David Woodhouse <David.Woodhouse-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org> for all 4, with
the caveat that I don't actually want to see various IOMMU drivers
*using* the IOVA code directly.

Where possible, we really want to be *losing* the separate DMA API
implementation, which would do nothing but call this library and then
use the underlying IOMMU API functions with the IOVAs that result.
Let the whole of that wrapper be generic, rather than just abstracting
out the IOVA allocator for everyone to use in their own wrapper.
-- 
dwmw2

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