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Subject[PATCH v6 18/19] swiotlb-xen: introduce a rbtree to track phys to bus mappings
Date
Introduce a second red-back tree to track phys to bus mappings created after
the initialization of the swiotlb buffer.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
---
drivers/xen/swiotlb-xen.c | 99 +++++++++++++++++++++++++++++++++++++-------
1 files changed, 83 insertions(+), 16 deletions(-)

diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index 3011736..022bcaf 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -79,7 +79,8 @@ struct xen_dma_info {
dma_addr_t dma_addr;
phys_addr_t phys_addr;
size_t size;
- struct rb_node rbnode;
+ struct rb_node rbnode_dma;
+ struct rb_node rbnode_phys;
};

/*
@@ -96,8 +97,13 @@ static struct xen_dma_info *xen_dma_seg;
* mappings.
*/
static struct rb_root bus_to_phys = RB_ROOT;
+/*
+ * This tree keeps track of physical address to bus address
+ * mappings apart from the ones belonging to the initial swiotlb buffer.
+ */
+static struct rb_root phys_to_bus = RB_ROOT;

-static int xen_dma_add_entry(struct xen_dma_info *new)
+static int xen_dma_add_entry_bus(struct xen_dma_info *new)
{
struct rb_node **link = &bus_to_phys.rb_node;
struct rb_node *parent = NULL;
@@ -106,7 +112,7 @@ static int xen_dma_add_entry(struct xen_dma_info *new)

while (*link) {
parent = *link;
- entry = rb_entry(parent, struct xen_dma_info, rbnode);
+ entry = rb_entry(parent, struct xen_dma_info, rbnode_dma);

if (new->dma_addr == entry->dma_addr)
goto err_out;
@@ -118,8 +124,41 @@ static int xen_dma_add_entry(struct xen_dma_info *new)
else
link = &(*link)->rb_right;
}
- rb_link_node(&new->rbnode, parent, link);
- rb_insert_color(&new->rbnode, &bus_to_phys);
+ rb_link_node(&new->rbnode_dma, parent, link);
+ rb_insert_color(&new->rbnode_dma, &bus_to_phys);
+ goto out;
+
+err_out:
+ rc = -EINVAL;
+ pr_warn("%s: cannot add phys=%pa -> dma=%pa: phys=%pa -> dma=%pa already exists\n",
+ __func__, &new->phys_addr, &new->dma_addr, &entry->phys_addr, &entry->dma_addr);
+out:
+ return rc;
+}
+
+static int xen_dma_add_entry_phys(struct xen_dma_info *new)
+{
+ struct rb_node **link = &phys_to_bus.rb_node;
+ struct rb_node *parent = NULL;
+ struct xen_dma_info *entry;
+ int rc = 0;
+
+ while (*link) {
+ parent = *link;
+ entry = rb_entry(parent, struct xen_dma_info, rbnode_phys);
+
+ if (new->dma_addr == entry->dma_addr)
+ goto err_out;
+ if (new->phys_addr == entry->phys_addr)
+ goto err_out;
+
+ if (new->phys_addr < entry->phys_addr)
+ link = &(*link)->rb_left;
+ else
+ link = &(*link)->rb_right;
+ }
+ rb_link_node(&new->rbnode_phys, parent, link);
+ rb_insert_color(&new->rbnode_phys, &phys_to_bus);
goto out;

err_out:
@@ -130,13 +169,22 @@ out:
return rc;
}

+static int xen_dma_add_entry(struct xen_dma_info *new)
+{
+ int rc;
+ if ((rc = xen_dma_add_entry_bus(new) < 0) ||
+ (rc = xen_dma_add_entry_phys(new) < 0))
+ return rc;
+ return 0;
+}
+
static struct xen_dma_info *xen_get_dma_info_from_dma(dma_addr_t dma_addr)
{
struct rb_node *n = bus_to_phys.rb_node;
struct xen_dma_info *entry;

while (n) {
- entry = rb_entry(n, struct xen_dma_info, rbnode);
+ entry = rb_entry(n, struct xen_dma_info, rbnode_dma);
if (entry->dma_addr <= dma_addr &&
entry->dma_addr + entry->size > dma_addr) {
return entry;
@@ -150,11 +198,30 @@ static struct xen_dma_info *xen_get_dma_info_from_dma(dma_addr_t dma_addr)
return NULL;
}

-static dma_addr_t xen_phys_to_bus(phys_addr_t paddr)
+static struct xen_dma_info *xen_get_dma_info_from_phys(phys_addr_t phys)
{
- int nr_seg;
- unsigned long offset;
- char *vaddr;
+ struct rb_node *n = phys_to_bus.rb_node;
+ struct xen_dma_info *entry;
+
+ while (n) {
+ entry = rb_entry(n, struct xen_dma_info, rbnode_phys);
+ if (entry->phys_addr <= phys &&
+ entry->phys_addr + entry->size > phys) {
+ return entry;
+ }
+ if (phys < entry->phys_addr)
+ n = n->rb_left;
+ else
+ n = n->rb_right;
+ }
+
+ return NULL;
+}
+
+/* Only looks into the initial buffer allocation in case of
+ * XENFEAT_auto_translated_physmap guests. */
+static dma_addr_t xen_phys_to_bus_quick(phys_addr_t paddr) { int nr_seg;
+ unsigned long offset; char *vaddr;

if (!xen_feature(XENFEAT_auto_translated_physmap))
return phys_to_machine(XPADDR(paddr)).maddr;
@@ -184,7 +251,7 @@ static phys_addr_t xen_bus_to_phys(dma_addr_t baddr)

static dma_addr_t xen_virt_to_bus(void *address)
{
- return xen_phys_to_bus(virt_to_phys(address));
+ return xen_phys_to_bus_quick(virt_to_phys(address));
}

static int check_pages_physically_contiguous(unsigned long pfn,
@@ -424,7 +491,7 @@ xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
* Do not use virt_to_phys(ret) because on ARM it doesn't correspond
* to *dma_handle. */
phys = *dma_handle;
- dev_addr = xen_phys_to_bus(phys);
+ dev_addr = xen_phys_to_bus_quick(phys);
if (!xen_feature(XENFEAT_auto_translated_physmap) &&
((dev_addr + size - 1 <= dma_mask)) &&
!range_straddles_page_boundary(phys, size))
@@ -503,7 +570,7 @@ dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page,
struct dma_attrs *attrs)
{
phys_addr_t map, phys = page_to_phys(page) + offset;
- dma_addr_t dev_addr = xen_phys_to_bus(phys);
+ dma_addr_t dev_addr = xen_phys_to_bus_quick(phys);

BUG_ON(dir == DMA_NONE);
/*
@@ -527,7 +594,7 @@ dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page,
if (map == SWIOTLB_MAP_ERROR)
return DMA_ERROR_CODE;

- dev_addr = xen_phys_to_bus(map);
+ dev_addr = xen_phys_to_bus_quick(map);

/*
* Ensure that the address returned is DMA'ble
@@ -656,7 +723,7 @@ xen_swiotlb_map_sg_attrs(struct device *hwdev, struct scatterlist *sgl,

for_each_sg(sgl, sg, nelems, i) {
phys_addr_t paddr = sg_phys(sg);
- dma_addr_t dev_addr = xen_phys_to_bus(paddr);
+ dma_addr_t dev_addr = xen_phys_to_bus_quick(paddr);

if (swiotlb_force ||
xen_feature(XENFEAT_auto_translated_physmap) ||
@@ -682,7 +749,7 @@ xen_swiotlb_map_sg_attrs(struct device *hwdev, struct scatterlist *sgl,
sg_dma_len(sgl) = 0;
return DMA_ERROR_CODE;
}
- sg->dma_address = xen_phys_to_bus(map);
+ sg->dma_address = xen_phys_to_bus_quick(map);
} else
sg->dma_address = dev_addr;
sg_dma_len(sg) = sg->length;
--
1.7.2.5


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