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Commit bb68b2fb authored by Robin Murphy's avatar Robin Murphy Committed by Joerg Roedel
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iommu/iova: Add rbtree anchor node 



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: default avatarRobin Murphy <robin.murphy@arm.com>
Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
parent aa3ac946

drivers/iommu/iova.c

+13 −2
Original line number Diff line number Diff line
@@ -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);
@@ -242,6 +248,7 @@ EXPORT_SYMBOL(alloc_iova_mem); 


void free_iova_mem(struct iova *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)) {

include/linux/iova.h

+1 −0
Original line number Diff line number Diff line
@@ -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