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iommu/iova: Add rbtree anchor node

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Add a permanent dummy IOVA reservation to the rbtree, such that we can
always access the top of the address space instantly. The immediate
benefit is that we remove the overhead of the rb_last() traversal when
not using the cached node, but it also paves the way for further
simplifications.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
This commit is contained in:
Robin Murphy 2017-09-21 16:52:46 +01:00 committed by Joerg Roedel
parent aa3ac9469c
commit bb68b2fbfb
2 changed files with 14 additions and 2 deletions
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15
drivers/iommu/iova.c
View File

@ -24,6 +24,9 @@
#include <linux/bitops.h>
#include <linux/cpu.h>
/* The anchor node sits above the top of the usable address space */
#define IOVA_ANCHOR ~0UL
static bool iova_rcache_insert(struct iova_domain *iovad,
unsigned long pfn,
unsigned long size);
@ -55,6 +58,9 @@ init_iova_domain(struct iova_domain *iovad, unsigned long granule,
iovad->dma_32bit_pfn = 1UL << (32 - iova_shift(iovad));
iovad->flush_cb = NULL;
iovad->fq = NULL;
iovad->anchor.pfn_lo = iovad->anchor.pfn_hi = IOVA_ANCHOR;
rb_link_node(&iovad->anchor.node, NULL, &iovad->rbroot.rb_node);
rb_insert_color(&iovad->anchor.node, &iovad->rbroot);
init_iova_rcaches(iovad);
}
EXPORT_SYMBOL_GPL(init_iova_domain);
@ -119,7 +125,7 @@ __get_cached_rbnode(struct iova_domain *iovad, unsigned long *limit_pfn)
if (!cached_node)
cached_node = iovad->cached_node;
if (!cached_node)
return rb_last(&iovad->rbroot);
return rb_prev(&iovad->anchor.node);
curr_iova = rb_entry(cached_node, struct iova, node);
*limit_pfn = min(*limit_pfn, curr_iova->pfn_lo);
@ -242,7 +248,8 @@ EXPORT_SYMBOL(alloc_iova_mem);
void free_iova_mem(struct iova *iova)
{
kmem_cache_free(iova_cache, iova);
if (iova->pfn_lo != IOVA_ANCHOR)
kmem_cache_free(iova_cache, iova);
}
EXPORT_SYMBOL(free_iova_mem);
@ -676,6 +683,10 @@ reserve_iova(struct iova_domain *iovad,
struct iova *iova;
unsigned int overlap = 0;
/* Don't allow nonsensical pfns */
if (WARN_ON((pfn_hi | pfn_lo) > (ULLONG_MAX >> iova_shift(iovad))))
return NULL;
spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
for (node = rb_first(&iovad->rbroot); node; node = rb_next(node)) {
if (__is_range_overlap(node, pfn_lo, pfn_hi)) {

1
include/linux/iova.h
View File

@ -75,6 +75,7 @@ struct iova_domain {
unsigned long granule; /* pfn granularity for this domain */
unsigned long start_pfn; /* Lower limit for this domain */
unsigned long dma_32bit_pfn;
struct iova anchor; /* rbtree lookup anchor */
struct iova_rcache rcaches[IOVA_RANGE_CACHE_MAX_SIZE]; /* IOVA range caches */
iova_flush_cb flush_cb; /* Call-Back function to flush IOMMU