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Commit d50582e0 authored by Stefano Stabellini's avatar Stefano Stabellini
Browse files

xen/arm: remove mach_to_phys rbtree 



Remove the rbtree used to keep track of machine to physical mappings:
the frontend can grant the same page multiple times, leading to errors
inserting or removing entries from the mach_to_phys tree.

Linux only needed to know the physical address corresponding to a given
machine address in swiotlb-xen. Now that swiotlb-xen can call the
xen_dma_* functions passing the machine address directly, we can remove
it.

Signed-off-by: default avatarStefano Stabellini <stefano.stabellini@eu.citrix.com>
Tested-by: default avatarDenis Schneider <v1ne2go@gmail.com>
parent 340720be

arch/arm/include/asm/xen/page.h

+0 −9
Original line number Diff line number Diff line
@@ -33,7 +33,6 @@ typedef struct xpaddr { 
#define INVALID_P2M_ENTRY      (~0UL)



unsigned long __pfn_to_mfn(unsigned long pfn);

unsigned long __mfn_to_pfn(unsigned long mfn);

extern struct rb_root phys_to_mach;



static inline unsigned long pfn_to_mfn(unsigned long pfn)
@@ -51,14 +50,6 @@ static inline unsigned long pfn_to_mfn(unsigned long pfn) 


static inline unsigned long mfn_to_pfn(unsigned long mfn)

{

	unsigned long pfn;



	if (phys_to_mach.rb_node != NULL) {

		pfn = __mfn_to_pfn(mfn);

		if (pfn != INVALID_P2M_ENTRY)

			return pfn;

	}



	return mfn;

}

arch/arm/xen/p2m.c

+1 −65
Original line number Diff line number Diff line
@@ -21,14 +21,12 @@ struct xen_p2m_entry { 
	unsigned long pfn;

	unsigned long mfn;

	unsigned long nr_pages;

	struct rb_node rbnode_mach;

	struct rb_node rbnode_phys;

};



static rwlock_t p2m_lock;

struct rb_root phys_to_mach = RB_ROOT;

EXPORT_SYMBOL_GPL(phys_to_mach);

static struct rb_root mach_to_phys = RB_ROOT;



static int xen_add_phys_to_mach_entry(struct xen_p2m_entry *new)

{
@@ -41,8 +39,6 @@ static int xen_add_phys_to_mach_entry(struct xen_p2m_entry *new) 
		parent = *link;

		entry = rb_entry(parent, struct xen_p2m_entry, rbnode_phys);



		if (new->mfn == entry->mfn)

			goto err_out;

		if (new->pfn == entry->pfn)

			goto err_out;
@@ -88,64 +84,6 @@ unsigned long __pfn_to_mfn(unsigned long pfn) 
}

EXPORT_SYMBOL_GPL(__pfn_to_mfn);



static int xen_add_mach_to_phys_entry(struct xen_p2m_entry *new)

{

	struct rb_node **link = &mach_to_phys.rb_node;

	struct rb_node *parent = NULL;

	struct xen_p2m_entry *entry;

	int rc = 0;



	while (*link) {

		parent = *link;

		entry = rb_entry(parent, struct xen_p2m_entry, rbnode_mach);



		if (new->mfn == entry->mfn)

			goto err_out;

		if (new->pfn == entry->pfn)

			goto err_out;



		if (new->mfn < entry->mfn)

			link = &(*link)->rb_left;

		else

			link = &(*link)->rb_right;

	}

	rb_link_node(&new->rbnode_mach, parent, link);

	rb_insert_color(&new->rbnode_mach, &mach_to_phys);

	goto out;



err_out:

	rc = -EINVAL;

	pr_warn("%s: cannot add pfn=%pa -> mfn=%pa: pfn=%pa -> mfn=%pa already exists\n",

			__func__, &new->pfn, &new->mfn, &entry->pfn, &entry->mfn);

out:

	return rc;

}



unsigned long __mfn_to_pfn(unsigned long mfn)

{

	struct rb_node *n = mach_to_phys.rb_node;

	struct xen_p2m_entry *entry;

	unsigned long irqflags;



	read_lock_irqsave(&p2m_lock, irqflags);

	while (n) {

		entry = rb_entry(n, struct xen_p2m_entry, rbnode_mach);

		if (entry->mfn <= mfn &&

				entry->mfn + entry->nr_pages > mfn) {

			read_unlock_irqrestore(&p2m_lock, irqflags);

			return entry->pfn + (mfn - entry->mfn);

		}

		if (mfn < entry->mfn)

			n = n->rb_left;

		else

			n = n->rb_right;

	}

	read_unlock_irqrestore(&p2m_lock, irqflags);



	return INVALID_P2M_ENTRY;

}

EXPORT_SYMBOL_GPL(__mfn_to_pfn);



int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,

			    struct gnttab_map_grant_ref *kmap_ops,

			    struct page **pages, unsigned int count)
@@ -192,7 +130,6 @@ bool __set_phys_to_machine_multi(unsigned long pfn, 
			p2m_entry = rb_entry(n, struct xen_p2m_entry, rbnode_phys);

			if (p2m_entry->pfn <= pfn &&

					p2m_entry->pfn + p2m_entry->nr_pages > pfn) {

				rb_erase(&p2m_entry->rbnode_mach, &mach_to_phys);

				rb_erase(&p2m_entry->rbnode_phys, &phys_to_mach);

				write_unlock_irqrestore(&p2m_lock, irqflags);

				kfree(p2m_entry);
@@ -217,8 +154,7 @@ bool __set_phys_to_machine_multi(unsigned long pfn, 
	p2m_entry->mfn = mfn;



	write_lock_irqsave(&p2m_lock, irqflags);

	if ((rc = xen_add_phys_to_mach_entry(p2m_entry) < 0) ||

		(rc = xen_add_mach_to_phys_entry(p2m_entry) < 0)) {

	if ((rc = xen_add_phys_to_mach_entry(p2m_entry)) < 0) {

		write_unlock_irqrestore(&p2m_lock, irqflags);

		return false;

	}