1 files changed, 482 insertions, 131 deletions

diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index ff0aa74afaa..d4d52f5a1cf 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -40,12 +40,15 @@
  */
 #include <linux/sched.h>
 #include <linux/highmem.h>
+#include <linux/debugfs.h>
 #include <linux/bug.h>
 
 #include <asm/pgtable.h>
 #include <asm/tlbflush.h>
+#include <asm/fixmap.h>
 #include <asm/mmu_context.h>
 #include <asm/paravirt.h>
+#include <asm/linkage.h>
 
 #include <asm/xen/hypercall.h>
 #include <asm/xen/hypervisor.h>
@@ -55,27 +58,85 @@
 
 #include "multicalls.h"
 #include "mmu.h"
+#include "debugfs.h"
+
+#define MMU_UPDATE_HISTO	30
+
+#ifdef CONFIG_XEN_DEBUG_FS
+
+static struct {
+	u32 pgd_update;
+	u32 pgd_update_pinned;
+	u32 pgd_update_batched;
+
+	u32 pud_update;
+	u32 pud_update_pinned;
+	u32 pud_update_batched;
+
+	u32 pmd_update;
+	u32 pmd_update_pinned;
+	u32 pmd_update_batched;
+
+	u32 pte_update;
+	u32 pte_update_pinned;
+	u32 pte_update_batched;
+
+	u32 mmu_update;
+	u32 mmu_update_extended;
+	u32 mmu_update_histo[MMU_UPDATE_HISTO];
+
+	u32 prot_commit;
+	u32 prot_commit_batched;
+
+	u32 set_pte_at;
+	u32 set_pte_at_batched;
+	u32 set_pte_at_pinned;
+	u32 set_pte_at_current;
+	u32 set_pte_at_kernel;
+} mmu_stats;
+
+static u8 zero_stats;
+
+static inline void check_zero(void)
+{
+	if (unlikely(zero_stats)) {
+		memset(&mmu_stats, 0, sizeof(mmu_stats));
+		zero_stats = 0;
+	}
+}
+
+#define ADD_STATS(elem, val)			\
+	do { check_zero(); mmu_stats.elem += (val); } while(0)
+
+#else  /* !CONFIG_XEN_DEBUG_FS */
+
+#define ADD_STATS(elem, val)	do { (void)(val); } while(0)
+
+#endif /* CONFIG_XEN_DEBUG_FS */
+
+/*
+ * Just beyond the highest usermode address.  STACK_TOP_MAX has a
+ * redzone above it, so round it up to a PGD boundary.
+ */
+#define USER_LIMIT	((STACK_TOP_MAX + PGDIR_SIZE - 1) & PGDIR_MASK)
+
 
 #define P2M_ENTRIES_PER_PAGE	(PAGE_SIZE / sizeof(unsigned long))
 #define TOP_ENTRIES		(MAX_DOMAIN_PAGES / P2M_ENTRIES_PER_PAGE)
 
 /* Placeholder for holes in the address space */
-static unsigned long p2m_missing[P2M_ENTRIES_PER_PAGE]
-	__attribute__((section(".data.page_aligned"))) =
+static unsigned long p2m_missing[P2M_ENTRIES_PER_PAGE] __page_aligned_data =
 		{ [ 0 ... P2M_ENTRIES_PER_PAGE-1 ] = ~0UL };
 
  /* Array of pointers to pages containing p2m entries */
-static unsigned long *p2m_top[TOP_ENTRIES]
-	__attribute__((section(".data.page_aligned"))) =
+static unsigned long *p2m_top[TOP_ENTRIES] __page_aligned_data =
 		{ [ 0 ... TOP_ENTRIES - 1] = &p2m_missing[0] };
 
 /* Arrays of p2m arrays expressed in mfns used for save/restore */
-static unsigned long p2m_top_mfn[TOP_ENTRIES]
-	__attribute__((section(".bss.page_aligned")));
+static unsigned long p2m_top_mfn[TOP_ENTRIES] __page_aligned_bss;
 
-static unsigned long p2m_top_mfn_list[
-			PAGE_ALIGN(TOP_ENTRIES / P2M_ENTRIES_PER_PAGE)]
-	__attribute__((section(".bss.page_aligned")));
+static unsigned long p2m_top_mfn_list[TOP_ENTRIES / P2M_ENTRIES_PER_PAGE]
+	__page_aligned_bss;
 
 static inline unsigned p2m_top_index(unsigned long pfn)
 {
@@ -181,15 +242,16 @@ void set_phys_to_machine(unsigned long pfn, unsigned long mfn)
 	p2m_top[topidx][idx] = mfn;
 }
 
-xmaddr_t arbitrary_virt_to_machine(unsigned long address)
+xmaddr_t arbitrary_virt_to_machine(void *vaddr)
 {
+	unsigned long address = (unsigned long)vaddr;
 	unsigned int level;
 	pte_t *pte = lookup_address(address, &level);
 	unsigned offset = address & ~PAGE_MASK;
 
 	BUG_ON(pte == NULL);
 
-	return XMADDR((pte_mfn(*pte) << PAGE_SHIFT) + offset);
+	return XMADDR(((phys_addr_t)pte_mfn(*pte) << PAGE_SHIFT) + offset);
 }
 
 void make_lowmem_page_readonly(void *vaddr)
@@ -223,25 +285,35 @@ void make_lowmem_page_readwrite(void *vaddr)
 }
 
 
-static bool page_pinned(void *ptr)
+static bool xen_page_pinned(void *ptr)
 {
 	struct page *page = virt_to_page(ptr);
 
 	return PagePinned(page);
 }
 
-static void extend_mmu_update(const struct mmu_update *update)
+static void xen_extend_mmu_update(const struct mmu_update *update)
 {
 	struct multicall_space mcs;
 	struct mmu_update *u;
 
 	mcs = xen_mc_extend_args(__HYPERVISOR_mmu_update, sizeof(*u));
 
-	if (mcs.mc != NULL)
+	if (mcs.mc != NULL) {
+		ADD_STATS(mmu_update_extended, 1);
+		ADD_STATS(mmu_update_histo[mcs.mc->args[1]], -1);
+
 		mcs.mc->args[1]++;
-	else {
+
+		if (mcs.mc->args[1] < MMU_UPDATE_HISTO)
+			ADD_STATS(mmu_update_histo[mcs.mc->args[1]], 1);
+		else
+			ADD_STATS(mmu_update_histo[0], 1);
+	} else {
+		ADD_STATS(mmu_update, 1);
 		mcs = __xen_mc_entry(sizeof(*u));
 		MULTI_mmu_update(mcs.mc, mcs.args, 1, NULL, DOMID_SELF);
+		ADD_STATS(mmu_update_histo[1], 1);
 	}
 
 	u = mcs.args;
@@ -256,9 +328,12 @@ void xen_set_pmd_hyper(pmd_t *ptr, pmd_t val)
 
 	xen_mc_batch();
 
-	u.ptr = virt_to_machine(ptr).maddr;
+	/* ptr may be ioremapped for 64-bit pagetable setup */
+	u.ptr = arbitrary_virt_to_machine(ptr).maddr;
 	u.val = pmd_val_ma(val);
-	extend_mmu_update(&u);
+	xen_extend_mmu_update(&u);
+
+	ADD_STATS(pmd_update_batched, paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU);
 
 	xen_mc_issue(PARAVIRT_LAZY_MMU);
 
@@ -267,13 +342,17 @@ void xen_set_pmd_hyper(pmd_t *ptr, pmd_t val)
 
 void xen_set_pmd(pmd_t *ptr, pmd_t val)
 {
+	ADD_STATS(pmd_update, 1);
+
 	/* If page is not pinned, we can just update the entry
 	   directly */
-	if (!page_pinned(ptr)) {
+	if (!xen_page_pinned(ptr)) {
 		*ptr = val;
 		return;
 	}
 
+	ADD_STATS(pmd_update_pinned, 1);
+
 	xen_set_pmd_hyper(ptr, val);
 }
 
@@ -283,35 +362,7 @@ void xen_set_pmd(pmd_t *ptr, pmd_t val)
  */
 void set_pte_mfn(unsigned long vaddr, unsigned long mfn, pgprot_t flags)
 {
-	pgd_t *pgd;
-	pud_t *pud;
-	pmd_t *pmd;
-	pte_t *pte;
-
-	pgd = swapper_pg_dir + pgd_index(vaddr);
-	if (pgd_none(*pgd)) {
-		BUG();
-		return;
-	}
-	pud = pud_offset(pgd, vaddr);
-	if (pud_none(*pud)) {
-		BUG();
-		return;
-	}
-	pmd = pmd_offset(pud, vaddr);
-	if (pmd_none(*pmd)) {
-		BUG();
-		return;
-	}
-	pte = pte_offset_kernel(pmd, vaddr);
-	/* <mfn,flags> stored as-is, to permit clearing entries */
-	xen_set_pte(pte, mfn_pte(mfn, flags));
-
-	/*
-	 * It's enough to flush this one mapping.
-	 * (PGE mappings get flushed as well)
-	 */
-	__flush_tlb_one(vaddr);
+	set_pte_vaddr(vaddr, mfn_pte(mfn, flags));
 }
 
 void xen_set_pte_at(struct mm_struct *mm, unsigned long addr,
@@ -321,12 +372,18 @@ void xen_set_pte_at(struct mm_struct *mm, unsigned long addr,
 	if (mm == &init_mm)
 		preempt_disable();
 
+	ADD_STATS(set_pte_at, 1);
+//	ADD_STATS(set_pte_at_pinned, xen_page_pinned(ptep));
+	ADD_STATS(set_pte_at_current, mm == current->mm);
+	ADD_STATS(set_pte_at_kernel, mm == &init_mm);
+
 	if (mm == current->mm || mm == &init_mm) {
 		if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) {
 			struct multicall_space mcs;
 			mcs = xen_mc_entry(0);
 
 			MULTI_update_va_mapping(mcs.mc, addr, pteval, 0);
+			ADD_STATS(set_pte_at_batched, 1);
 			xen_mc_issue(PARAVIRT_LAZY_MMU);
 			goto out;
 		} else
@@ -355,7 +412,10 @@ void xen_ptep_modify_prot_commit(struct mm_struct *mm, unsigned long addr,
 
 	u.ptr = virt_to_machine(ptep).maddr | MMU_PT_UPDATE_PRESERVE_AD;
 	u.val = pte_val_ma(pte);
-	extend_mmu_update(&u);
+	xen_extend_mmu_update(&u);
+
+	ADD_STATS(prot_commit, 1);
+	ADD_STATS(prot_commit_batched, paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU);
 
 	xen_mc_issue(PARAVIRT_LAZY_MMU);
 }
@@ -364,8 +424,8 @@ void xen_ptep_modify_prot_commit(struct mm_struct *mm, unsigned long addr,
 static pteval_t pte_mfn_to_pfn(pteval_t val)
 {
 	if (val & _PAGE_PRESENT) {
-		unsigned long mfn = (val & PTE_MASK) >> PAGE_SHIFT;
-		pteval_t flags = val & ~PTE_MASK;
+		unsigned long mfn = (val & PTE_PFN_MASK) >> PAGE_SHIFT;
+		pteval_t flags = val & PTE_FLAGS_MASK;
 		val = ((pteval_t)mfn_to_pfn(mfn) << PAGE_SHIFT) | flags;
 	}
 
@@ -375,8 +435,8 @@ static pteval_t pte_mfn_to_pfn(pteval_t val)
 static pteval_t pte_pfn_to_mfn(pteval_t val)
 {
 	if (val & _PAGE_PRESENT) {
-		unsigned long pfn = (val & PTE_MASK) >> PAGE_SHIFT;
-		pteval_t flags = val & ~PTE_MASK;
+		unsigned long pfn = (val & PTE_PFN_MASK) >> PAGE_SHIFT;
+		pteval_t flags = val & PTE_FLAGS_MASK;
 		val = ((pteval_t)pfn_to_mfn(pfn) << PAGE_SHIFT) | flags;
 	}
 
@@ -418,9 +478,12 @@ void xen_set_pud_hyper(pud_t *ptr, pud_t val)
 
 	xen_mc_batch();
 
-	u.ptr = virt_to_machine(ptr).maddr;
+	/* ptr may be ioremapped for 64-bit pagetable setup */
+	u.ptr = arbitrary_virt_to_machine(ptr).maddr;
 	u.val = pud_val_ma(val);
-	extend_mmu_update(&u);
+	xen_extend_mmu_update(&u);
+
+	ADD_STATS(pud_update_batched, paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU);
 
 	xen_mc_issue(PARAVIRT_LAZY_MMU);
 
@@ -429,26 +492,39 @@ void xen_set_pud_hyper(pud_t *ptr, pud_t val)
 
 void xen_set_pud(pud_t *ptr, pud_t val)
 {
+	ADD_STATS(pud_update, 1);
+
 	/* If page is not pinned, we can just update the entry
 	   directly */
-	if (!page_pinned(ptr)) {
+	if (!xen_page_pinned(ptr)) {
 		*ptr = val;
 		return;
 	}
 
+	ADD_STATS(pud_update_pinned, 1);
+
 	xen_set_pud_hyper(ptr, val);
 }
 
 void xen_set_pte(pte_t *ptep, pte_t pte)
 {
+	ADD_STATS(pte_update, 1);
+//	ADD_STATS(pte_update_pinned, xen_page_pinned(ptep));
+	ADD_STATS(pte_update_batched, paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU);
+
+#ifdef CONFIG_X86_PAE
 	ptep->pte_high = pte.pte_high;
 	smp_wmb();
 	ptep->pte_low = pte.pte_low;
+#else
+	*ptep = pte;
+#endif
 }
 
+#ifdef CONFIG_X86_PAE
 void xen_set_pte_atomic(pte_t *ptep, pte_t pte)
 {
-	set_64bit((u64 *)ptep, pte_val_ma(pte));
+	set_64bit((u64 *)ptep, native_pte_val(pte));
 }
 
 void xen_pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
@@ -462,6 +538,7 @@ void xen_pmd_clear(pmd_t *pmdp)
 {
 	set_pmd(pmdp, __pmd(0));
 }
+#endif	/* CONFIG_X86_PAE */
 
 pmd_t xen_make_pmd(pmdval_t pmd)
 {
@@ -469,95 +546,218 @@ pmd_t xen_make_pmd(pmdval_t pmd)
 	return native_make_pmd(pmd);
 }
 
+#if PAGETABLE_LEVELS == 4
+pudval_t xen_pud_val(pud_t pud)
+{
+	return pte_mfn_to_pfn(pud.pud);
+}
+
+pud_t xen_make_pud(pudval_t pud)
+{
+	pud = pte_pfn_to_mfn(pud);
+
+	return native_make_pud(pud);
+}
+
+pgd_t *xen_get_user_pgd(pgd_t *pgd)
+{
+	pgd_t *pgd_page = (pgd_t *)(((unsigned long)pgd) & PAGE_MASK);
+	unsigned offset = pgd - pgd_page;
+	pgd_t *user_ptr = NULL;
+
+	if (offset < pgd_index(USER_LIMIT)) {
+		struct page *page = virt_to_page(pgd_page);
+		user_ptr = (pgd_t *)page->private;
+		if (user_ptr)
+			user_ptr += offset;
+	}
+
+	return user_ptr;
+}
+
+static void __xen_set_pgd_hyper(pgd_t *ptr, pgd_t val)
+{
+	struct mmu_update u;
+
+	u.ptr = virt_to_machine(ptr).maddr;
+	u.val = pgd_val_ma(val);
+	xen_extend_mmu_update(&u);
+}
+
 /*
-  (Yet another) pagetable walker.  This one is intended for pinning a
-  pagetable.  This means that it walks a pagetable and calls the
-  callback function on each page it finds making up the page table,
-  at every level.  It walks the entire pagetable, but it only bothers
-  pinning pte pages which are below pte_limit.  In the normal case
-  this will be TASK_SIZE, but at boot we need to pin up to
-  FIXADDR_TOP.  But the important bit is that we don't pin beyond
-  there, because then we start getting into Xen's ptes.
-*/
-static int pgd_walk(pgd_t *pgd_base, int (*func)(struct page *, enum pt_level),
-		    unsigned long limit)
-{
-	pgd_t *pgd = pgd_base;
+ * Raw hypercall-based set_pgd, intended for in early boot before
+ * there's a page structure.  This implies:
+ *  1. The only existing pagetable is the kernel's
+ *  2. It is always pinned
+ *  3. It has no user pagetable attached to it
+ */
+void __init xen_set_pgd_hyper(pgd_t *ptr, pgd_t val)
+{
+	preempt_disable();
+
+	xen_mc_batch();
+
+	__xen_set_pgd_hyper(ptr, val);
+
+	xen_mc_issue(PARAVIRT_LAZY_MMU);
+
+	preempt_enable();
+}
+
+void xen_set_pgd(pgd_t *ptr, pgd_t val)
+{
+	pgd_t *user_ptr = xen_get_user_pgd(ptr);
+
+	ADD_STATS(pgd_update, 1);
+
+	/* If page is not pinned, we can just update the entry
+	   directly */
+	if (!xen_page_pinned(ptr)) {
+		*ptr = val;
+		if (user_ptr) {
+			WARN_ON(xen_page_pinned(user_ptr));
+			*user_ptr = val;
+		}
+		return;
+	}
+
+	ADD_STATS(pgd_update_pinned, 1);
+	ADD_STATS(pgd_update_batched, paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU);
+
+	/* If it's pinned, then we can at least batch the kernel and
+	   user updates together. */
+	xen_mc_batch();
+
+	__xen_set_pgd_hyper(ptr, val);
+	if (user_ptr)
+		__xen_set_pgd_hyper(user_ptr, val);
+
+	xen_mc_issue(PARAVIRT_LAZY_MMU);
+}
+#endif	/* PAGETABLE_LEVELS == 4 */
+
+/*
+ * (Yet another) pagetable walker.  This one is intended for pinning a
+ * pagetable.  This means that it walks a pagetable and calls the
+ * callback function on each page it finds making up the page table,
+ * at every level.  It walks the entire pagetable, but it only bothers
+ * pinning pte pages which are below limit.  In the normal case this
+ * will be STACK_TOP_MAX, but at boot we need to pin up to
+ * FIXADDR_TOP.
+ *
+ * For 32-bit the important bit is that we don't pin beyond there,
+ * because then we start getting into Xen's ptes.
+ *
+ * For 64-bit, we must skip the Xen hole in the middle of the address
+ * space, just after the big x86-64 virtual hole.
+ */
+static int xen_pgd_walk(struct mm_struct *mm,
+			int (*func)(struct mm_struct *mm, struct page *,
+				    enum pt_level),
+			unsigned long limit)
+{
+	pgd_t *pgd = mm->pgd;
 	int flush = 0;
-	unsigned long addr = 0;
-	unsigned long pgd_next;
+	unsigned hole_low, hole_high;
+	unsigned pgdidx_limit, pudidx_limit, pmdidx_limit;
+	unsigned pgdidx, pudidx, pmdidx;
 
-	BUG_ON(limit > FIXADDR_TOP);
+	/* The limit is the last byte to be touched */
+	limit--;
+	BUG_ON(limit >= FIXADDR_TOP);
 
 	if (xen_feature(XENFEAT_auto_translated_physmap))
 		return 0;
 
-	for (; addr != FIXADDR_TOP; pgd++, addr = pgd_next) {
+	/*
+	 * 64-bit has a great big hole in the middle of the address
+	 * space, which contains the Xen mappings.  On 32-bit these
+	 * will end up making a zero-sized hole and so is a no-op.
+	 */
+	hole_low = pgd_index(USER_LIMIT);
+	hole_high = pgd_index(PAGE_OFFSET);
+
+	pgdidx_limit = pgd_index(limit);
+#if PTRS_PER_PUD > 1
+	pudidx_limit = pud_index(limit);
+#else
+	pudidx_limit = 0;
+#endif
+#if PTRS_PER_PMD > 1
+	pmdidx_limit = pmd_index(limit);
+#else
+	pmdidx_limit = 0;
+#endif
+
+	for (pgdidx = 0; pgdidx <= pgdidx_limit; pgdidx++) {
 		pud_t *pud;
-		unsigned long pud_limit, pud_next;
 
-		pgd_next = pud_limit = pgd_addr_end(addr, FIXADDR_TOP);
+		if (pgdidx >= hole_low && pgdidx < hole_high)
+			continue;
 
-		if (!pgd_val(*pgd))
+		if (!pgd_val(pgd[pgdidx]))
 			continue;
 
-		pud = pud_offset(pgd, 0);
+		pud = pud_offset(&pgd[pgdidx], 0);
 
 		if (PTRS_PER_PUD > 1) /* not folded */
-			flush |= (*func)(virt_to_page(pud), PT_PUD);
+			flush |= (*func)(mm, virt_to_page(pud), PT_PUD);
 
-		for (; addr != pud_limit; pud++, addr = pud_next) {
+		for (pudidx = 0; pudidx < PTRS_PER_PUD; pudidx++) {
 			pmd_t *pmd;
-			unsigned long pmd_limit;
-
-			pud_next = pud_addr_end(addr, pud_limit);
 
-			if (pud_next < limit)
-				pmd_limit = pud_next;
-			else
-				pmd_limit = limit;
+			if (pgdidx == pgdidx_limit &&
+			    pudidx > pudidx_limit)
+				goto out;
 
-			if (pud_none(*pud))
+			if (pud_none(pud[pudidx]))
 				continue;
 
-			pmd = pmd_offset(pud, 0);
+			pmd = pmd_offset(&pud[pudidx], 0);
 
 			if (PTRS_PER_PMD > 1) /* not folded */
-				flush |= (*func)(virt_to_page(pmd), PT_PMD);
+				flush |= (*func)(mm, virt_to_page(pmd), PT_PMD);
+
+			for (pmdidx = 0; pmdidx < PTRS_PER_PMD; pmdidx++) {
+				struct page *pte;
 
-			for (; addr != pmd_limit; pmd++) {
-				addr += (PAGE_SIZE * PTRS_PER_PTE);
-				if ((pmd_limit-1) < (addr-1)) {
-					addr = pmd_limit;
-					break;
-				}
+				if (pgdidx == pgdidx_limit &&
+				    pudidx == pudidx_limit &&
+				    pmdidx > pmdidx_limit)
+					goto out;
 
-				if (pmd_none(*pmd))
+				if (pmd_none(pmd[pmdidx]))
 					continue;
 
-				flush |= (*func)(pmd_page(*pmd), PT_PTE);
+				pte = pmd_page(pmd[pmdidx]);
+				flush |= (*func)(mm, pte, PT_PTE);
 			}
 		}
 	}
 
-	flush |= (*func)(virt_to_page(pgd_base), PT_PGD);
+out:
+	/* Do the top level last, so that the callbacks can use it as
+	   a cue to do final things like tlb flushes. */
+	flush |= (*func)(mm, virt_to_page(pgd), PT_PGD);
 
 	return flush;
 }
 
-static spinlock_t *lock_pte(struct page *page)
+/* If we're using split pte locks, then take the page's lock and
+   return a pointer to it.  Otherwise return NULL. */
+static spinlock_t *xen_pte_lock(struct page *page, struct mm_struct *mm)
 {
 	spinlock_t *ptl = NULL;
 
-#if NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS
+#if USE_SPLIT_PTLOCKS
 	ptl = __pte_lockptr(page);
-	spin_lock(ptl);
+	spin_lock_nest_lock(ptl, &mm->page_table_lock);
 #endif
 
 	return ptl;
 }
 
-static void do_unlock(void *v)
+static void xen_pte_unlock(void *v)
 {
 	spinlock_t *ptl = v;
 	spin_unlock(ptl);
@@ -575,7 +775,8 @@ static void xen_do_pin(unsigned level, unsigned long pfn)
 	MULTI_mmuext_op(mcs.mc, op, 1, NULL, DOMID_SELF);
 }
 
-static int pin_page(struct page *page, enum pt_level level)
+static int xen_pin_page(struct mm_struct *mm, struct page *page,
+			enum pt_level level)
 {
 	unsigned pgfl = TestSetPagePinned(page);
 	int flush;
@@ -594,21 +795,40 @@ static int pin_page(struct page *page, enum pt_level level)
 
 		flush = 0;
 
+		/*
+		 * We need to hold the pagetable lock between the time
+		 * we make the pagetable RO and when we actually pin
+		 * it.  If we don't, then other users may come in and
+		 * attempt to update the pagetable by writing it,
+		 * which will fail because the memory is RO but not
+		 * pinned, so Xen won't do the trap'n'emulate.
+		 *
+		 * If we're using split pte locks, we can't hold the
+		 * entire pagetable's worth of locks during the
+		 * traverse, because we may wrap the preempt count (8
+		 * bits).  The solution is to mark RO and pin each PTE
+		 * page while holding the lock.  This means the number
+		 * of locks we end up holding is never more than a
+		 * batch size (~32 entries, at present).
+		 *
+		 * If we're not using split pte locks, we needn't pin
+		 * the PTE pages independently, because we're
+		 * protected by the overall pagetable lock.
+		 */
 		ptl = NULL;
 		if (level == PT_PTE)
-			ptl = lock_pte(page);
+			ptl = xen_pte_lock(page, mm);
 
 		MULTI_update_va_mapping(mcs.mc, (unsigned long)pt,
 					pfn_pte(pfn, PAGE_KERNEL_RO),
 					level == PT_PGD ? UVMF_TLB_FLUSH : 0);
 
-		if (level == PT_PTE)
+		if (ptl) {
 			xen_do_pin(MMUEXT_PIN_L1_TABLE, pfn);
 
-		if (ptl) {
 			/* Queue a deferred unlock for when this batch
 			   is completed. */
-			xen_mc_callback(do_unlock, ptl);
+			xen_mc_callback(xen_pte_unlock, ptl);
 		}
 	}
 
@@ -618,26 +838,54 @@ static int pin_page(struct page *page, enum pt_level level)
 /* This is called just after a mm has been created, but it has not
    been used yet.  We need to make sure that its pagetable is all
    read-only, and can be pinned. */
-void xen_pgd_pin(pgd_t *pgd)
+static void __xen_pgd_pin(struct mm_struct *mm, pgd_t *pgd)
 {
 	xen_mc_batch();
 
-	if (pgd_walk(pgd, pin_page, TASK_SIZE)) {
+	if (xen_pgd_walk(mm, xen_pin_page, USER_LIMIT)) {
 		/* re-enable interrupts for kmap_flush_unused */
 		xen_mc_issue(0);
 		kmap_flush_unused();
+		vm_unmap_aliases();
 		xen_mc_batch();
 	}
 
+#ifdef CONFIG_X86_64
+	{
+		pgd_t *user_pgd = xen_get_user_pgd(pgd);
+
+		xen_do_pin(MMUEXT_PIN_L4_TABLE, PFN_DOWN(__pa(pgd)));
+
+		if (user_pgd) {
+			xen_pin_page(mm, virt_to_page(user_pgd), PT_PGD);
+			xen_do_pin(MMUEXT_PIN_L4_TABLE, PFN_DOWN(__pa(user_pgd)));
+		}
+	}
+#else /* CONFIG_X86_32 */
+#ifdef CONFIG_X86_PAE
+	/* Need to make sure unshared kernel PMD is pinnable */
+	xen_pin_page(mm, virt_to_page(pgd_page(pgd[pgd_index(TASK_SIZE)])),
+		     PT_PMD);
+#endif
 	xen_do_pin(MMUEXT_PIN_L3_TABLE, PFN_DOWN(__pa(pgd)));
+#endif /* CONFIG_X86_64 */
 	xen_mc_issue(0);
 }
 
+static void xen_pgd_pin(struct mm_struct *mm)
+{
+	__xen_pgd_pin(mm, mm->pgd);
+}
+
 /*
  * On save, we need to pin all pagetables to make sure they get their
  * mfns turned into pfns.  Search the list for any unpinned pgds and pin
  * them (unpinned pgds are not currently in use, probably because the
  * process is under construction or destruction).
+ *
+ * Expected to be called in stop_machine() ("equivalent to taking
+ * every spinlock in the system"), so the locking doesn't really
+ * matter all that much.
  */
 void xen_mm_pin_all(void)
 {
@@ -648,7 +896,7 @@ void xen_mm_pin_all(void)
 
 	list_for_each_entry(page, &pgd_list, lru) {
 		if (!PagePinned(page)) {
-			xen_pgd_pin((pgd_t *)page_address(page));
+			__xen_pgd_pin(&init_mm, (pgd_t *)page_address(page));
 			SetPageSavePinned(page);
 		}
 	}
@@ -656,10 +904,13 @@ void xen_mm_pin_all(void)
 	spin_unlock_irqrestore(&pgd_lock, flags);
 }
 
-/* The init_mm pagetable is really pinned as soon as its created, but
-   that's before we have page structures to store the bits.  So do all
-   the book-keeping now. */
-static __init int mark_pinned(struct page *page, enum pt_level level)
+/*
+ * The init_mm pagetable is really pinned as soon as its created, but
+ * that's before we have page structures to store the bits.  So do all
+ * the book-keeping now.
+ */
+static __init int xen_mark_pinned(struct mm_struct *mm, struct page *page,
+				  enum pt_level level)
 {
 	SetPagePinned(page);
 	return 0;
@@ -667,10 +918,11 @@ static __init int mark_pinned(struct page *page, enum pt_level level)
 
 void __init xen_mark_init_mm_pinned(void)
 {
-	pgd_walk(init_mm.pgd, mark_pinned, FIXADDR_TOP);
+	xen_pgd_walk(&init_mm, xen_mark_pinned, FIXADDR_TOP);
 }
 
-static int unpin_page(struct page *page, enum pt_level level)
+static int xen_unpin_page(struct mm_struct *mm, struct page *page,
+			  enum pt_level level)
 {
 	unsigned pgfl = TestClearPagePinned(page);
 
@@ -680,10 +932,18 @@ static int unpin_page(struct page *page, enum pt_level level)
 		spinlock_t *ptl = NULL;
 		struct multicall_space mcs;
 
+		/*
+		 * Do the converse to pin_page.  If we're using split
+		 * pte locks, we must be holding the lock for while
+		 * the pte page is unpinned but still RO to prevent
+		 * concurrent updates from seeing it in this
+		 * partially-pinned state.
+		 */
 		if (level == PT_PTE) {
-			ptl = lock_pte(page);
+			ptl = xen_pte_lock(page, mm);
 
-			xen_do_pin(MMUEXT_UNPIN_TABLE, pfn);
+			if (ptl)
+				xen_do_pin(MMUEXT_UNPIN_TABLE, pfn);
 		}
 
 		mcs = __xen_mc_entry(0);
@@ -694,7 +954,7 @@ static int unpin_page(struct page *page, enum pt_level level)
 
 		if (ptl) {
 			/* unlock when batch completed */
-			xen_mc_callback(do_unlock, ptl);
+			xen_mc_callback(xen_pte_unlock, ptl);
 		}
 	}
 
@@ -702,17 +962,39 @@ static int unpin_page(struct page *page, enum pt_level level)
 }
 
 /* Release a pagetables pages back as normal RW */
-static void xen_pgd_unpin(pgd_t *pgd)
+static void __xen_pgd_unpin(struct mm_struct *mm, pgd_t *pgd)
 {
 	xen_mc_batch();
 
 	xen_do_pin(MMUEXT_UNPIN_TABLE, PFN_DOWN(__pa(pgd)));
 
-	pgd_walk(pgd, unpin_page, TASK_SIZE);
+#ifdef CONFIG_X86_64
+	{
+		pgd_t *user_pgd = xen_get_user_pgd(pgd);
+
+		if (user_pgd) {
+			xen_do_pin(MMUEXT_UNPIN_TABLE, PFN_DOWN(__pa(user_pgd)));
+			xen_unpin_page(mm, virt_to_page(user_pgd), PT_PGD);
+		}
+	}
+#endif
+
+#ifdef CONFIG_X86_PAE
+	/* Need to make sure unshared kernel PMD is unpinned */
+	xen_unpin_page(mm, virt_to_page(pgd_page(pgd[pgd_index(TASK_SIZE)])),
+		       PT_PMD);
+#endif
+
+	xen_pgd_walk(mm, xen_unpin_page, USER_LIMIT);
 
 	xen_mc_issue(0);
 }
 
+static void xen_pgd_unpin(struct mm_struct *mm)
+{
+	__xen_pgd_unpin(mm, mm->pgd);
+}
+
 /*
  * On resume, undo any pinning done at save, so that the rest of the
  * kernel doesn't see any unexpected pinned pagetables.
@@ -727,8 +1009,7 @@ void xen_mm_unpin_all(void)
 	list_for_each_entry(page, &pgd_list, lru) {
 		if (PageSavePinned(page)) {
 			BUG_ON(!PagePinned(page));
-			printk("unpinning pinned %p\n", page_address(page));
-			xen_pgd_unpin((pgd_t *)page_address(page));
+			__xen_pgd_unpin(&init_mm, (pgd_t *)page_address(page));
 			ClearPageSavePinned(page);
 		}
 	}
@@ -739,14 +1020,14 @@ void xen_mm_unpin_all(void)
 void xen_activate_mm(struct mm_struct *prev, struct mm_struct *next)
 {
 	spin_lock(&next->page_table_lock);
-	xen_pgd_pin(next->pgd);
+	xen_pgd_pin(next);
 	spin_unlock(&next->page_table_lock);
 }
 
 void xen_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm)
 {
 	spin_lock(&mm->page_table_lock);
-	xen_pgd_pin(mm->pgd);
+	xen_pgd_pin(mm);
 	spin_unlock(&mm->page_table_lock);
 }
 
@@ -757,8 +1038,15 @@ void xen_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm)
 static void drop_other_mm_ref(void *info)
 {
 	struct mm_struct *mm = info;
+	struct mm_struct *active_mm;
 
-	if (__get_cpu_var(cpu_tlbstate).active_mm == mm)
+#ifdef CONFIG_X86_64
+	active_mm = read_pda(active_mm);
+#else
+	active_mm = __get_cpu_var(cpu_tlbstate).active_mm;
+#endif
+
+	if (active_mm == mm)
 		leave_mm(smp_processor_id());
 
 	/* If this cpu still has a stale cr3 reference, then make sure
@@ -769,7 +1057,7 @@ static void drop_other_mm_ref(void *info)
 	}
 }
 
-static void drop_mm_ref(struct mm_struct *mm)
+static void xen_drop_mm_ref(struct mm_struct *mm)
 {
 	cpumask_t mask;
 	unsigned cpu;
@@ -799,7 +1087,7 @@ static void drop_mm_ref(struct mm_struct *mm)
 		smp_call_function_mask(mask, drop_other_mm_ref, mm, 1);
 }
 #else
-static void drop_mm_ref(struct mm_struct *mm)
+static void xen_drop_mm_ref(struct mm_struct *mm)
 {
 	if (current->active_mm == mm)
 		load_cr3(swapper_pg_dir);
@@ -823,14 +1111,77 @@ static void drop_mm_ref(struct mm_struct *mm)
 void xen_exit_mmap(struct mm_struct *mm)
 {
 	get_cpu();		/* make sure we don't move around */
-	drop_mm_ref(mm);
+	xen_drop_mm_ref(mm);
 	put_cpu();
 
 	spin_lock(&mm->page_table_lock);
 
 	/* pgd may not be pinned in the error exit path of execve */
-	if (page_pinned(mm->pgd))
-		xen_pgd_unpin(mm->pgd);
+	if (xen_page_pinned(mm->pgd))
+		xen_pgd_unpin(mm);
 
 	spin_unlock(&mm->page_table_lock);
 }
+
+#ifdef CONFIG_XEN_DEBUG_FS
+
+static struct dentry *d_mmu_debug;
+
+static int __init xen_mmu_debugfs(void)
+{
+	struct dentry *d_xen = xen_init_debugfs();
+
+	if (d_xen == NULL)
+		return -ENOMEM;
+
+	d_mmu_debug = debugfs_create_dir("mmu", d_xen);
+
+	debugfs_create_u8("zero_stats", 0644, d_mmu_debug, &zero_stats);
+
+	debugfs_create_u32("pgd_update", 0444, d_mmu_debug, &mmu_stats.pgd_update);
+	debugfs_create_u32("pgd_update_pinned", 0444, d_mmu_debug,
+			   &mmu_stats.pgd_update_pinned);
+	debugfs_create_u32("pgd_update_batched", 0444, d_mmu_debug,
+			   &mmu_stats.pgd_update_pinned);
+
+	debugfs_create_u32("pud_update", 0444, d_mmu_debug, &mmu_stats.pud_update);
+	debugfs_create_u32("pud_update_pinned", 0444, d_mmu_debug,
+			   &mmu_stats.pud_update_pinned);
+	debugfs_create_u32("pud_update_batched", 0444, d_mmu_debug,
+			   &mmu_stats.pud_update_pinned);
+
+	debugfs_create_u32("pmd_update", 0444, d_mmu_debug, &mmu_stats.pmd_update);
+	debugfs_create_u32("pmd_update_pinned", 0444, d_mmu_debug,
+			   &mmu_stats.pmd_update_pinned);
+	debugfs_create_u32("pmd_update_batched", 0444, d_mmu_debug,
+			   &mmu_stats.pmd_update_pinned);
+
+	debugfs_create_u32("pte_update", 0444, d_mmu_debug, &mmu_stats.pte_update);
+//	debugfs_create_u32("pte_update_pinned", 0444, d_mmu_debug,
+//			   &mmu_stats.pte_update_pinned);
+	debugfs_create_u32("pte_update_batched", 0444, d_mmu_debug,
+			   &mmu_stats.pte_update_pinned);
+
+	debugfs_create_u32("mmu_update", 0444, d_mmu_debug, &mmu_stats.mmu_update);
+	debugfs_create_u32("mmu_update_extended", 0444, d_mmu_debug,
+			   &mmu_stats.mmu_update_extended);
+	xen_debugfs_create_u32_array("mmu_update_histo", 0444, d_mmu_debug,
+				     mmu_stats.mmu_update_histo, 20);
+
+	debugfs_create_u32("set_pte_at", 0444, d_mmu_debug, &mmu_stats.set_pte_at);
+	debugfs_create_u32("set_pte_at_batched", 0444, d_mmu_debug,
+			   &mmu_stats.set_pte_at_batched);
+	debugfs_create_u32("set_pte_at_current", 0444, d_mmu_debug,
+			   &mmu_stats.set_pte_at_current);
+	debugfs_create_u32("set_pte_at_kernel", 0444, d_mmu_debug,
+			   &mmu_stats.set_pte_at_kernel);
+
+	debugfs_create_u32("prot_commit", 0444, d_mmu_debug, &mmu_stats.prot_commit);
+	debugfs_create_u32("prot_commit_batched", 0444, d_mmu_debug,
+			   &mmu_stats.prot_commit_batched);
+
+	return 0;
+}
+fs_initcall(xen_mmu_debugfs);
+
+#endif	/* CONFIG_XEN_DEBUG_FS */