[v7,05/10] iommu/dma-reserved-iommu: reserved binding rb-tree and helpers

Message ID 1461084994-2355-6-git-send-email-eric.auger@linaro.org
State New
Headers show

Commit Message

Auger Eric April 19, 2016, 4:56 p.m.
we will need to track which host physical addresses are mapped to
reserved IOVA. In that prospect we introduce a new RB tree indexed
by physical address. This RB tree only is used for reserved IOVA
bindings.

It is expected this RB tree will contain very few bindings. Those
generally correspond to single page mapping one MSI frame (GICv2m
frame or ITS GITS_TRANSLATER frame).

Signed-off-by: Eric Auger <eric.auger@linaro.org>


---
v5 -> v6:
- add comment about @d->reserved_lock to be held

v3 -> v4:
- that code was formerly in "iommu/arm-smmu: add a reserved binding RB tree"
---
 drivers/iommu/dma-reserved-iommu.c | 63 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)

-- 
1.9.1

Comments

Auger Eric April 20, 2016, 4:18 p.m. | #1
Robin,
On 04/20/2016 03:12 PM, Robin Murphy wrote:
> On 19/04/16 17:56, Eric Auger wrote:

>> we will need to track which host physical addresses are mapped to

>> reserved IOVA. In that prospect we introduce a new RB tree indexed

>> by physical address. This RB tree only is used for reserved IOVA

>> bindings.

>>

>> It is expected this RB tree will contain very few bindings.

> 

> Sounds like a good reason in favour of using a list, and thus having

> rather less code here ;)


OK will move to a simple list.
> 

>>  Those

>> generally correspond to single page mapping one MSI frame (GICv2m

>> frame or ITS GITS_TRANSLATER frame).

>>

>> Signed-off-by: Eric Auger <eric.auger@linaro.org>

>>

>> ---

>> v5 -> v6:

>> - add comment about @d->reserved_lock to be held

>>

>> v3 -> v4:

>> - that code was formerly in "iommu/arm-smmu: add a reserved binding RB

>> tree"

>> ---

>>   drivers/iommu/dma-reserved-iommu.c | 63

>> ++++++++++++++++++++++++++++++++++++++

>>   1 file changed, 63 insertions(+)

>>

>> diff --git a/drivers/iommu/dma-reserved-iommu.c

>> b/drivers/iommu/dma-reserved-iommu.c

>> index 2562af0..f6fa18e 100644

>> --- a/drivers/iommu/dma-reserved-iommu.c

>> +++ b/drivers/iommu/dma-reserved-iommu.c

>> @@ -23,6 +23,69 @@ struct reserved_iova_domain {

>>       int prot; /* iommu protection attributes to be obeyed */

>>   };

>>

>> +struct iommu_reserved_binding {

>> +    struct kref        kref;

>> +    struct rb_node        node;

>> +    struct iommu_domain    *domain;

> 

> Hang on, the tree these are in is already embedded in a domain. Ergo we

> can't look them up without first knowing the domain they belong to, so

> what purpose does this guy serve?

this is used on the kref_put. The release function takes a kref; then we
get the container to retrieve the binding and storing the domain here
enables to unlink the node.

Best Regards

Eric
> 

> Robin.

> 

>> +    phys_addr_t        addr;

>> +    dma_addr_t        iova;

>> +    size_t            size;

>> +};

>> +

>> +/* Reserved binding RB-tree manipulation */

>> +

>> +/* @d->reserved_lock must be held */

>> +static struct iommu_reserved_binding *find_reserved_binding(

>> +                    struct iommu_domain *d,

>> +                    phys_addr_t start, size_t size)

>> +{

>> +    struct rb_node *node = d->reserved_binding_list.rb_node;

>> +

>> +    while (node) {

>> +        struct iommu_reserved_binding *binding =

>> +            rb_entry(node, struct iommu_reserved_binding, node);

>> +

>> +        if (start + size <= binding->addr)

>> +            node = node->rb_left;

>> +        else if (start >= binding->addr + binding->size)

>> +            node = node->rb_right;

>> +        else

>> +            return binding;

>> +    }

>> +

>> +    return NULL;

>> +}

>> +

>> +/* @d->reserved_lock must be held */

>> +static void link_reserved_binding(struct iommu_domain *d,

>> +                  struct iommu_reserved_binding *new)

>> +{

>> +    struct rb_node **link = &d->reserved_binding_list.rb_node;

>> +    struct rb_node *parent = NULL;

>> +    struct iommu_reserved_binding *binding;

>> +

>> +    while (*link) {

>> +        parent = *link;

>> +        binding = rb_entry(parent, struct iommu_reserved_binding,

>> +                   node);

>> +

>> +        if (new->addr + new->size <= binding->addr)

>> +            link = &(*link)->rb_left;

>> +        else

>> +            link = &(*link)->rb_right;

>> +    }

>> +

>> +    rb_link_node(&new->node, parent, link);

>> +    rb_insert_color(&new->node, &d->reserved_binding_list);

>> +}

>> +

>> +/* @d->reserved_lock must be held */

>> +static void unlink_reserved_binding(struct iommu_domain *d,

>> +                    struct iommu_reserved_binding *old)

>> +{

>> +    rb_erase(&old->node, &d->reserved_binding_list);

>> +}

>> +

>>   int iommu_alloc_reserved_iova_domain(struct iommu_domain *domain,

>>                        dma_addr_t iova, size_t size, int prot,

>>                        unsigned long order)

>>

>

Patch

diff --git a/drivers/iommu/dma-reserved-iommu.c b/drivers/iommu/dma-reserved-iommu.c
index 2562af0..f6fa18e 100644
--- a/drivers/iommu/dma-reserved-iommu.c
+++ b/drivers/iommu/dma-reserved-iommu.c
@@ -23,6 +23,69 @@  struct reserved_iova_domain {
 	int prot; /* iommu protection attributes to be obeyed */
 };
 
+struct iommu_reserved_binding {
+	struct kref		kref;
+	struct rb_node		node;
+	struct iommu_domain	*domain;
+	phys_addr_t		addr;
+	dma_addr_t		iova;
+	size_t			size;
+};
+
+/* Reserved binding RB-tree manipulation */
+
+/* @d->reserved_lock must be held */
+static struct iommu_reserved_binding *find_reserved_binding(
+				    struct iommu_domain *d,
+				    phys_addr_t start, size_t size)
+{
+	struct rb_node *node = d->reserved_binding_list.rb_node;
+
+	while (node) {
+		struct iommu_reserved_binding *binding =
+			rb_entry(node, struct iommu_reserved_binding, node);
+
+		if (start + size <= binding->addr)
+			node = node->rb_left;
+		else if (start >= binding->addr + binding->size)
+			node = node->rb_right;
+		else
+			return binding;
+	}
+
+	return NULL;
+}
+
+/* @d->reserved_lock must be held */
+static void link_reserved_binding(struct iommu_domain *d,
+				  struct iommu_reserved_binding *new)
+{
+	struct rb_node **link = &d->reserved_binding_list.rb_node;
+	struct rb_node *parent = NULL;
+	struct iommu_reserved_binding *binding;
+
+	while (*link) {
+		parent = *link;
+		binding = rb_entry(parent, struct iommu_reserved_binding,
+				   node);
+
+		if (new->addr + new->size <= binding->addr)
+			link = &(*link)->rb_left;
+		else
+			link = &(*link)->rb_right;
+	}
+
+	rb_link_node(&new->node, parent, link);
+	rb_insert_color(&new->node, &d->reserved_binding_list);
+}
+
+/* @d->reserved_lock must be held */
+static void unlink_reserved_binding(struct iommu_domain *d,
+				    struct iommu_reserved_binding *old)
+{
+	rb_erase(&old->node, &d->reserved_binding_list);
+}
+
 int iommu_alloc_reserved_iova_domain(struct iommu_domain *domain,
 				     dma_addr_t iova, size_t size, int prot,
 				     unsigned long order)