3 files changed, 14 insertions, 344 deletions

diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h
index e9f52fe2d56a..358dcd338915 100644
--- a/arch/x86/include/asm/xen/page.h
+++ b/arch/x86/include/asm/xen/page.h
@@ -57,7 +57,6 @@ extern int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
 extern int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
 				     struct gnttab_unmap_grant_ref *kunmap_ops,
 				     struct page **pages, unsigned int count);
-extern unsigned long m2p_find_override_pfn(unsigned long mfn, unsigned long pfn);
 
 /*
  * Helper functions to write or read unsigned long values to/from
@@ -154,21 +153,12 @@ static inline unsigned long mfn_to_pfn(unsigned long mfn)
 		return mfn;
 
 	pfn = mfn_to_pfn_no_overrides(mfn);
-	if (__pfn_to_mfn(pfn) != mfn) {
-		/*
-		 * If this appears to be a foreign mfn (because the pfn
-		 * doesn't map back to the mfn), then check the local override
-		 * table to see if there's a better pfn to use.
-		 *
-		 * m2p_find_override_pfn returns ~0 if it doesn't find anything.
-		 */
-		pfn = m2p_find_override_pfn(mfn, ~0);
-	}
+	if (__pfn_to_mfn(pfn) != mfn)
+		pfn = ~0;
 
 	/*
-	 * pfn is ~0 if there are no entries in the m2p for mfn or if the
-	 * entry doesn't map back to the mfn and m2p_override doesn't have a
-	 * valid entry for it.
+	 * pfn is ~0 if there are no entries in the m2p for mfn or the
+	 * entry doesn't map back to the mfn.
 	 */
 	if (pfn == ~0 && __pfn_to_mfn(mfn) == IDENTITY_FRAME(mfn))
 		pfn = mfn;
diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
index df40b2888eae..c9bc53f64359 100644
--- a/arch/x86/xen/p2m.c
+++ b/arch/x86/xen/p2m.c
@@ -84,8 +84,6 @@
 
 #define PMDS_PER_MID_PAGE	(P2M_MID_PER_PAGE / PTRS_PER_PTE)
 
-static void __init m2p_override_init(void);
-
 unsigned long *xen_p2m_addr __read_mostly;
 EXPORT_SYMBOL_GPL(xen_p2m_addr);
 unsigned long xen_p2m_size __read_mostly;
@@ -402,8 +400,6 @@ void __init xen_vmalloc_p2m_tree(void)
 	xen_p2m_size = xen_max_p2m_pfn;
 
 	xen_inv_extra_mem();
-
-	m2p_override_init();
 }
 
 unsigned long get_phys_to_machine(unsigned long pfn)
@@ -652,100 +648,21 @@ bool set_phys_to_machine(unsigned long pfn, unsigned long mfn)
 	return true;
 }
 
-#define M2P_OVERRIDE_HASH_SHIFT	10
-#define M2P_OVERRIDE_HASH	(1 << M2P_OVERRIDE_HASH_SHIFT)
-
-static struct list_head *m2p_overrides;
-static DEFINE_SPINLOCK(m2p_override_lock);
-
-static void __init m2p_override_init(void)
-{
-	unsigned i;
-
-	m2p_overrides = alloc_bootmem_align(
-				sizeof(*m2p_overrides) * M2P_OVERRIDE_HASH,
-				sizeof(unsigned long));
-
-	for (i = 0; i < M2P_OVERRIDE_HASH; i++)
-		INIT_LIST_HEAD(&m2p_overrides[i]);
-}
-
-static unsigned long mfn_hash(unsigned long mfn)
-{
-	return hash_long(mfn, M2P_OVERRIDE_HASH_SHIFT);
-}
-
-/* Add an MFN override for a particular page */
-static int m2p_add_override(unsigned long mfn, struct page *page,
-			    struct gnttab_map_grant_ref *kmap_op)
-{
-	unsigned long flags;
-	unsigned long pfn;
-	unsigned long uninitialized_var(address);
-	unsigned level;
-	pte_t *ptep = NULL;
-
-	pfn = page_to_pfn(page);
-	if (!PageHighMem(page)) {
-		address = (unsigned long)__va(pfn << PAGE_SHIFT);
-		ptep = lookup_address(address, &level);
-		if (WARN(ptep == NULL || level != PG_LEVEL_4K,
-			 "m2p_add_override: pfn %lx not mapped", pfn))
-			return -EINVAL;
-	}
-
-	if (kmap_op != NULL) {
-		if (!PageHighMem(page)) {
-			struct multicall_space mcs =
-				xen_mc_entry(sizeof(*kmap_op));
-
-			MULTI_grant_table_op(mcs.mc,
-					GNTTABOP_map_grant_ref, kmap_op, 1);
-
-			xen_mc_issue(PARAVIRT_LAZY_MMU);
-		}
-	}
-	spin_lock_irqsave(&m2p_override_lock, flags);
-	list_add(&page->lru,  &m2p_overrides[mfn_hash(mfn)]);
-	spin_unlock_irqrestore(&m2p_override_lock, flags);
-
-	/* p2m(m2p(mfn)) == mfn: the mfn is already present somewhere in
-	 * this domain. Set the FOREIGN_FRAME_BIT in the p2m for the other
-	 * pfn so that the following mfn_to_pfn(mfn) calls will return the
-	 * pfn from the m2p_override (the backend pfn) instead.
-	 * We need to do this because the pages shared by the frontend
-	 * (xen-blkfront) can be already locked (lock_page, called by
-	 * do_read_cache_page); when the userspace backend tries to use them
-	 * with direct_IO, mfn_to_pfn returns the pfn of the frontend, so
-	 * do_blockdev_direct_IO is going to try to lock the same pages
-	 * again resulting in a deadlock.
-	 * As a side effect get_user_pages_fast might not be safe on the
-	 * frontend pages while they are being shared with the backend,
-	 * because mfn_to_pfn (that ends up being called by GUPF) will
-	 * return the backend pfn rather than the frontend pfn. */
-	pfn = mfn_to_pfn_no_overrides(mfn);
-	if (__pfn_to_mfn(pfn) == mfn)
-		set_phys_to_machine(pfn, FOREIGN_FRAME(mfn));
-
-	return 0;
-}
-
 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;
+	if (kmap_ops) {
+		ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref,
+						kmap_ops, count);
+		if (ret)
+			goto out;
 	}
 
 	for (i = 0; i < count; i++) {
@@ -773,160 +690,22 @@ int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
 			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);
 
-static struct page *m2p_find_override(unsigned long mfn)
-{
-	unsigned long flags;
-	struct list_head *bucket;
-	struct page *p, *ret;
-
-	if (unlikely(!m2p_overrides))
-		return NULL;
-
-	ret = NULL;
-	bucket = &m2p_overrides[mfn_hash(mfn)];
-
-	spin_lock_irqsave(&m2p_override_lock, flags);
-
-	list_for_each_entry(p, bucket, lru) {
-		if (page_private(p) == mfn) {
-			ret = p;
-			break;
-		}
-	}
-
-	spin_unlock_irqrestore(&m2p_override_lock, flags);
-
-	return ret;
-}
-
-static int m2p_remove_override(struct page *page,
-			       struct gnttab_unmap_grant_ref *kunmap_op,
-			       unsigned long mfn)
-{
-	unsigned long flags;
-	unsigned long pfn;
-	unsigned long uninitialized_var(address);
-	unsigned level;
-	pte_t *ptep = NULL;
-
-	pfn = page_to_pfn(page);
-
-	if (!PageHighMem(page)) {
-		address = (unsigned long)__va(pfn << PAGE_SHIFT);
-		ptep = lookup_address(address, &level);
-
-		if (WARN(ptep == NULL || level != PG_LEVEL_4K,
-			 "m2p_remove_override: pfn %lx not mapped", pfn))
-			return -EINVAL;
-	}
-
-	spin_lock_irqsave(&m2p_override_lock, flags);
-	list_del(&page->lru);
-	spin_unlock_irqrestore(&m2p_override_lock, flags);
-
-	if (kunmap_op != NULL) {
-		if (!PageHighMem(page)) {
-			struct multicall_space mcs;
-			struct gnttab_unmap_and_replace *unmap_op;
-			struct page *scratch_page = get_balloon_scratch_page();
-			unsigned long scratch_page_address = (unsigned long)
-				__va(page_to_pfn(scratch_page) << PAGE_SHIFT);
-
-			/*
-			 * It might be that we queued all the m2p grant table
-			 * hypercalls in a multicall, then m2p_remove_override
-			 * get called before the multicall has actually been
-			 * issued. In this case handle is going to -1 because
-			 * it hasn't been modified yet.
-			 */
-			if (kunmap_op->handle == -1)
-				xen_mc_flush();
-			/*
-			 * Now if kmap_op->handle is negative it means that the
-			 * hypercall actually returned an error.
-			 */
-			if (kunmap_op->handle == GNTST_general_error) {
-				pr_warn("m2p_remove_override: pfn %lx mfn %lx, failed to modify kernel mappings",
-					pfn, mfn);
-				put_balloon_scratch_page();
-				return -1;
-			}
-
-			xen_mc_batch();
-
-			mcs = __xen_mc_entry(
-				sizeof(struct gnttab_unmap_and_replace));
-			unmap_op = mcs.args;
-			unmap_op->host_addr = kunmap_op->host_addr;
-			unmap_op->new_addr = scratch_page_address;
-			unmap_op->handle = kunmap_op->handle;
-
-			MULTI_grant_table_op(mcs.mc,
-				GNTTABOP_unmap_and_replace, unmap_op, 1);
-
-			mcs = __xen_mc_entry(0);
-			MULTI_update_va_mapping(mcs.mc, scratch_page_address,
-					pfn_pte(page_to_pfn(scratch_page),
-					PAGE_KERNEL_RO), 0);
-
-			xen_mc_issue(PARAVIRT_LAZY_MMU);
-
-			put_balloon_scratch_page();
-		}
-	}
-
-	/* p2m(m2p(mfn)) == FOREIGN_FRAME(mfn): the mfn is already present
-	 * somewhere in this domain, even before being added to the
-	 * m2p_override (see comment above in m2p_add_override).
-	 * If there are no other entries in the m2p_override corresponding
-	 * to this mfn, then remove the FOREIGN_FRAME_BIT from the p2m for
-	 * the original pfn (the one shared by the frontend): the backend
-	 * cannot do any IO on this page anymore because it has been
-	 * unshared. Removing the FOREIGN_FRAME_BIT from the p2m entry of
-	 * the original pfn causes mfn_to_pfn(mfn) to return the frontend
-	 * pfn again. */
-	mfn &= ~FOREIGN_FRAME_BIT;
-	pfn = mfn_to_pfn_no_overrides(mfn);
-	if (__pfn_to_mfn(pfn) == FOREIGN_FRAME(mfn) &&
-			m2p_find_override(mfn) == NULL)
-		set_phys_to_machine(pfn, mfn);
-
-	return 0;
-}
-
 int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
 			      struct gnttab_unmap_grant_ref *kunmap_ops,
 			      struct page **pages, unsigned int count)
 {
 	int i, ret = 0;
-	bool lazy = false;
 
 	if (xen_feature(XENFEAT_auto_translated_physmap))
 		return 0;
 
-	if (kunmap_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_to_mfn(page_to_pfn(pages[i]));
 		unsigned long pfn = page_to_pfn(pages[i]);
@@ -940,32 +719,15 @@ int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
 		WARN_ON(!PagePrivate(pages[i]));
 		ClearPagePrivate(pages[i]);
 		set_phys_to_machine(pfn, pages[i]->index);
-
-		if (kunmap_ops)
-			ret = m2p_remove_override(pages[i], &kunmap_ops[i], mfn);
-		if (ret)
-			goto out;
 	}
-
+	if (kunmap_ops)
+		ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref,
+						kunmap_ops, count);
 out:
-	if (lazy)
-		arch_leave_lazy_mmu_mode();
 	return ret;
 }
 EXPORT_SYMBOL_GPL(clear_foreign_p2m_mapping);
 
-unsigned long m2p_find_override_pfn(unsigned long mfn, unsigned long pfn)
-{
-	struct page *p = m2p_find_override(mfn);
-	unsigned long ret = pfn;
-
-	if (p)
-		ret = page_to_pfn(p);
-
-	return ret;
-}
-EXPORT_SYMBOL_GPL(m2p_find_override_pfn);
-
 #ifdef CONFIG_XEN_DEBUG_FS
 #include <linux/debugfs.h>
 #include "debugfs.h"
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index 3860d02729dc..0b52d92cb2e5 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -92,7 +92,6 @@ EXPORT_SYMBOL_GPL(balloon_stats);
 
 /* We increase/decrease in batches which fit in a page */
 static xen_pfn_t frame_list[PAGE_SIZE / sizeof(unsigned long)];
-static DEFINE_PER_CPU(struct page *, balloon_scratch_page);
 
 
 /* List of ballooned pages, threaded through the mem_map array. */
@@ -423,22 +422,12 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp)
 		page = pfn_to_page(pfn);
 
 #ifdef CONFIG_XEN_HAVE_PVMMU
-		/*
-		 * Ballooned out frames are effectively replaced with
-		 * a scratch frame.  Ensure direct mappings and the
-		 * p2m are consistent.
-		 */
 		if (!xen_feature(XENFEAT_auto_translated_physmap)) {
 			if (!PageHighMem(page)) {
-				struct page *scratch_page = get_balloon_scratch_page();
-
 				ret = HYPERVISOR_update_va_mapping(
 						(unsigned long)__va(pfn << PAGE_SHIFT),
-						pfn_pte(page_to_pfn(scratch_page),
-							PAGE_KERNEL_RO), 0);
+						__pte_ma(0), 0);
 				BUG_ON(ret);
-
-				put_balloon_scratch_page();
 			}
 			__set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
 		}
@@ -500,18 +489,6 @@ static void balloon_process(struct work_struct *work)
 	mutex_unlock(&balloon_mutex);
 }
 
-struct page *get_balloon_scratch_page(void)
-{
-	struct page *ret = get_cpu_var(balloon_scratch_page);
-	BUG_ON(ret == NULL);
-	return ret;
-}
-
-void put_balloon_scratch_page(void)
-{
-	put_cpu_var(balloon_scratch_page);
-}
-
 /* Resets the Xen limit, sets new target, and kicks off processing. */
 void balloon_set_new_target(unsigned long target)
 {
@@ -605,61 +582,13 @@ static void __init balloon_add_region(unsigned long start_pfn,
 	}
 }
 
-static int alloc_balloon_scratch_page(int cpu)
-{
-	if (per_cpu(balloon_scratch_page, cpu) != NULL)
-		return 0;
-
-	per_cpu(balloon_scratch_page, cpu) = alloc_page(GFP_KERNEL);
-	if (per_cpu(balloon_scratch_page, cpu) == NULL) {
-		pr_warn("Failed to allocate balloon_scratch_page for cpu %d\n", cpu);
-		return -ENOMEM;
-	}
-
-	return 0;
-}
-
-
-static int balloon_cpu_notify(struct notifier_block *self,
-				    unsigned long action, void *hcpu)
-{
-	int cpu = (long)hcpu;
-	switch (action) {
-	case CPU_UP_PREPARE:
-		if (alloc_balloon_scratch_page(cpu))
-			return NOTIFY_BAD;
-		break;
-	default:
-		break;
-	}
-	return NOTIFY_OK;
-}
-
-static struct notifier_block balloon_cpu_notifier = {
-	.notifier_call	= balloon_cpu_notify,
-};
-
 static int __init balloon_init(void)
 {
-	int i, cpu;
+	int i;
 
 	if (!xen_domain())
 		return -ENODEV;
 
-	if (!xen_feature(XENFEAT_auto_translated_physmap)) {
-		register_cpu_notifier(&balloon_cpu_notifier);
-
-		get_online_cpus();
-		for_each_online_cpu(cpu) {
-			if (alloc_balloon_scratch_page(cpu)) {
-				put_online_cpus();
-				unregister_cpu_notifier(&balloon_cpu_notifier);
-				return -ENOMEM;
-			}
-		}
-		put_online_cpus();
-	}
-
 	pr_info("Initialising balloon driver\n");
 
 	balloon_stats.current_pages = xen_pv_domain()
@@ -696,15 +625,4 @@ static int __init balloon_init(void)
 
 subsys_initcall(balloon_init);
 
-static int __init balloon_clear(void)
-{
-	int cpu;
-
-	for_each_possible_cpu(cpu)
-		per_cpu(balloon_scratch_page, cpu) = NULL;
-
-	return 0;
-}
-early_initcall(balloon_clear);
-
 MODULE_LICENSE("GPL");