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Commit 1429d46d authored by Zoltan Kiss's avatar Zoltan Kiss Committed by David Vrabel
Browse files

xen/grant-table: Refactor gnttab_[un]map_refs to avoid m2p_override 



The grant mapping API does m2p_override unnecessarily: only gntdev needs it,
for blkback and future netback patches it just cause a lock contention, as
those pages never go to userspace. Therefore this series does the following:
- the bulk of the original function (everything after the mapping hypercall)
  is moved to arch-dependent set/clear_foreign_p2m_mapping
- the "if (xen_feature(XENFEAT_auto_translated_physmap))" branch goes to ARM
- therefore the ARM function could be much smaller, the m2p_override stubs
  could be also removed
- on x86 the set_phys_to_machine calls were moved up to this new funcion
  from m2p_override functions
- and m2p_override functions are only called when there is a kmap_ops param

It also removes a stray space from arch/x86/include/asm/xen/page.h.

Signed-off-by: default avatarZoltan Kiss <zoltan.kiss@citrix.com>
Suggested-by: default avatarAnthony Liguori <aliguori@amazon.com>
Suggested-by: default avatarDavid Vrabel <david.vrabel@citrix.com>
Suggested-by: default avatarStefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: default avatarDavid Vrabel <david.vrabel@citrix.com>
Signed-off-by: default avatarStefano Stabellini <stefano.stabellini@eu.citrix.com>
parent 395edbb8

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

+6 −9
Original line number Diff line number Diff line
@@ -97,16 +97,13 @@ static inline pte_t *lookup_address(unsigned long address, unsigned int *level) 
	return NULL;

}



static inline int m2p_add_override(unsigned long mfn, struct page *page,

		struct gnttab_map_grant_ref *kmap_op)

{

	return 0;

}

extern 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);



static inline int m2p_remove_override(struct page *page, bool clear_pte)

{

	return 0;

}

extern int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,

				     struct gnttab_map_grant_ref *kmap_ops,

				     struct page **pages, unsigned int count);



bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn);

bool __set_phys_to_machine_multi(unsigned long pfn, unsigned long mfn,

arch/arm/xen/p2m.c

+32 −0
Original line number Diff line number Diff line
@@ -146,6 +146,38 @@ unsigned long __mfn_to_pfn(unsigned long mfn) 
}

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)

{

	int i;



	for (i = 0; i < count; i++) {

		if (map_ops[i].status)

			continue;

		set_phys_to_machine(map_ops[i].host_addr >> PAGE_SHIFT,

				    map_ops[i].dev_bus_addr >> PAGE_SHIFT);

	}



	return 0;

}

EXPORT_SYMBOL_GPL(set_foreign_p2m_mapping);



int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,

			      struct gnttab_map_grant_ref *kmap_ops,

			      struct page **pages, unsigned int count)

{

	int i;



	for (i = 0; i < count; i++) {

		set_phys_to_machine(unmap_ops[i].host_addr >> PAGE_SHIFT,

				    INVALID_P2M_ENTRY);

	}



	return 0;

}

EXPORT_SYMBOL_GPL(clear_foreign_p2m_mapping);



bool __set_phys_to_machine_multi(unsigned long pfn,

		unsigned long mfn, unsigned long nr_pages)

{

arch/x86/include/asm/xen/page.h

+9 −2
Original line number Diff line number Diff line
@@ -49,10 +49,17 @@ extern bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn); 
extern unsigned long set_phys_range_identity(unsigned long pfn_s,

					     unsigned long pfn_e);



extern 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);

extern int m2p_add_override(unsigned long mfn, struct page *page,

			    struct gnttab_map_grant_ref *kmap_op);

extern int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,

				     struct gnttab_map_grant_ref *kmap_ops,

				     struct page **pages, unsigned int count);

extern int m2p_remove_override(struct page *page,

				struct gnttab_map_grant_ref *kmap_op);

			       struct gnttab_map_grant_ref *kmap_op,

			       unsigned long mfn);

extern struct page *m2p_find_override(unsigned long mfn);

extern unsigned long m2p_find_override_pfn(unsigned long mfn, unsigned long pfn);

arch/x86/xen/p2m.c

+106 −15
Original line number Diff line number Diff line
@@ -881,6 +881,65 @@ static unsigned long mfn_hash(unsigned long mfn) 
	return hash_long(mfn, M2P_OVERRIDE_HASH_SHIFT);

}



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)

{

	int i, ret = 0;

	bool lazy = false;

	pte_t *pte;



	if (xen_feature(XENFEAT_auto_translated_physmap))

		return 0;



	if (kmap_ops &&

	    !in_interrupt() &&

	    paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) {

		arch_enter_lazy_mmu_mode();

		lazy = true;

	}



	for (i = 0; i < count; i++) {

		unsigned long mfn, pfn;



		/* Do not add to override if the map failed. */

		if (map_ops[i].status)

			continue;



		if (map_ops[i].flags & GNTMAP_contains_pte) {

			pte = (pte_t *) (mfn_to_virt(PFN_DOWN(map_ops[i].host_addr)) +

				(map_ops[i].host_addr & ~PAGE_MASK));

			mfn = pte_mfn(*pte);

		} else {

			mfn = PFN_DOWN(map_ops[i].dev_bus_addr);

		}

		pfn = page_to_pfn(pages[i]);



		WARN_ON(PagePrivate(pages[i]));

		SetPagePrivate(pages[i]);

		set_page_private(pages[i], mfn);

		pages[i]->index = pfn_to_mfn(pfn);



		if (unlikely(!set_phys_to_machine(pfn, FOREIGN_FRAME(mfn)))) {

			ret = -ENOMEM;

			goto out;

		}



		if (kmap_ops) {

			ret = m2p_add_override(mfn, pages[i], &kmap_ops[i]);

			if (ret)

				goto out;

		}

	}



out:

	if (lazy)

		arch_leave_lazy_mmu_mode();



	return ret;

}

EXPORT_SYMBOL_GPL(set_foreign_p2m_mapping);



/* Add an MFN override for a particular page */

int m2p_add_override(unsigned long mfn, struct page *page,

		struct gnttab_map_grant_ref *kmap_op)
@@ -899,13 +958,6 @@ int m2p_add_override(unsigned long mfn, struct page *page, 
					"m2p_add_override: pfn %lx not mapped", pfn))

			return -EINVAL;

	}

	WARN_ON(PagePrivate(page));

	SetPagePrivate(page);

	set_page_private(page, mfn);

	page->index = pfn_to_mfn(pfn);



	if (unlikely(!set_phys_to_machine(pfn, FOREIGN_FRAME(mfn))))

		return -ENOMEM;



	if (kmap_op != NULL) {

		if (!PageHighMem(page)) {
@@ -943,20 +995,62 @@ int m2p_add_override(unsigned long mfn, struct page *page, 
	return 0;

}

EXPORT_SYMBOL_GPL(m2p_add_override);



int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,

			      struct gnttab_map_grant_ref *kmap_ops,

			      struct page **pages, unsigned int count)

{

	int i, ret = 0;

	bool lazy = false;



	if (xen_feature(XENFEAT_auto_translated_physmap))

		return 0;



	if (kmap_ops &&

	    !in_interrupt() &&

	    paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) {

		arch_enter_lazy_mmu_mode();

		lazy = true;

	}



	for (i = 0; i < count; i++) {

		unsigned long mfn = get_phys_to_machine(page_to_pfn(pages[i]));

		unsigned long pfn = page_to_pfn(pages[i]);



		if (mfn == INVALID_P2M_ENTRY || !(mfn & FOREIGN_FRAME_BIT)) {

			ret = -EINVAL;

			goto out;

		}



		set_page_private(pages[i], INVALID_P2M_ENTRY);

		WARN_ON(!PagePrivate(pages[i]));

		ClearPagePrivate(pages[i]);

		set_phys_to_machine(pfn, pages[i]->index);



		if (kmap_ops)

			ret = m2p_remove_override(pages[i], &kmap_ops[i], mfn);

		if (ret)

			goto out;

	}



out:

	if (lazy)

		arch_leave_lazy_mmu_mode();

	return ret;

}

EXPORT_SYMBOL_GPL(clear_foreign_p2m_mapping);



int m2p_remove_override(struct page *page,

		struct gnttab_map_grant_ref *kmap_op)

			struct gnttab_map_grant_ref *kmap_op,

			unsigned long mfn)

{

	unsigned long flags;

	unsigned long mfn;

	unsigned long pfn;

	unsigned long uninitialized_var(address);

	unsigned level;

	pte_t *ptep = NULL;



	pfn = page_to_pfn(page);

	mfn = get_phys_to_machine(pfn);

	if (mfn == INVALID_P2M_ENTRY || !(mfn & FOREIGN_FRAME_BIT))

		return -EINVAL;



	if (!PageHighMem(page)) {

		address = (unsigned long)__va(pfn << PAGE_SHIFT);
@@ -970,10 +1064,7 @@ int m2p_remove_override(struct page *page, 
	spin_lock_irqsave(&m2p_override_lock, flags);

	list_del(&page->lru);

	spin_unlock_irqrestore(&m2p_override_lock, flags);

	WARN_ON(!PagePrivate(page));

	ClearPagePrivate(page);



	set_phys_to_machine(pfn, page->index);

	if (kmap_op != NULL) {

		if (!PageHighMem(page)) {

			struct multicall_space mcs;

drivers/xen/grant-table.c

+3 −70
Original line number Diff line number Diff line
@@ -933,9 +933,6 @@ int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops, 
		    struct page **pages, unsigned int count)

{

	int i, ret;

	bool lazy = false;

	pte_t *pte;

	unsigned long mfn;



	ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, map_ops, count);

	if (ret)
@@ -947,45 +944,7 @@ int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops, 
			gnttab_retry_eagain_gop(GNTTABOP_map_grant_ref, map_ops + i,

						&map_ops[i].status, __func__);



	/* this is basically a nop on x86 */

	if (xen_feature(XENFEAT_auto_translated_physmap)) {

		for (i = 0; i < count; i++) {

			if (map_ops[i].status)

				continue;

			set_phys_to_machine(map_ops[i].host_addr >> PAGE_SHIFT,

					map_ops[i].dev_bus_addr >> PAGE_SHIFT);

		}

		return ret;

	}



	if (!in_interrupt() && paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) {

		arch_enter_lazy_mmu_mode();

		lazy = true;

	}



	for (i = 0; i < count; i++) {

		/* Do not add to override if the map failed. */

		if (map_ops[i].status)

			continue;



		if (map_ops[i].flags & GNTMAP_contains_pte) {

			pte = (pte_t *) (mfn_to_virt(PFN_DOWN(map_ops[i].host_addr)) +

				(map_ops[i].host_addr & ~PAGE_MASK));

			mfn = pte_mfn(*pte);

		} else {

			mfn = PFN_DOWN(map_ops[i].dev_bus_addr);

		}

		ret = m2p_add_override(mfn, pages[i], kmap_ops ?

				       &kmap_ops[i] : NULL);

		if (ret)

			goto out;

	}



 out:

	if (lazy)

		arch_leave_lazy_mmu_mode();



	return ret;

	return set_foreign_p2m_mapping(map_ops, kmap_ops, pages, count);

}

EXPORT_SYMBOL_GPL(gnttab_map_refs);
@@ -993,39 +952,13 @@ int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops, 
		      struct gnttab_map_grant_ref *kmap_ops,

		      struct page **pages, unsigned int count)

{

	int i, ret;

	bool lazy = false;

	int ret;



	ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, unmap_ops, count);

	if (ret)

		return ret;



	/* this is basically a nop on x86 */

	if (xen_feature(XENFEAT_auto_translated_physmap)) {

		for (i = 0; i < count; i++) {

			set_phys_to_machine(unmap_ops[i].host_addr >> PAGE_SHIFT,

					INVALID_P2M_ENTRY);

		}

		return ret;

	}



	if (!in_interrupt() && paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) {

		arch_enter_lazy_mmu_mode();

		lazy = true;

	}



	for (i = 0; i < count; i++) {

		ret = m2p_remove_override(pages[i], kmap_ops ?

				       &kmap_ops[i] : NULL);

		if (ret)

			goto out;

	}



 out:

	if (lazy)

		arch_leave_lazy_mmu_mode();



	return ret;

	return clear_foreign_p2m_mapping(unmap_ops, kmap_ops, pages, count);

}

EXPORT_SYMBOL_GPL(gnttab_unmap_refs);