From: Jeremy Fitzhardinge <jeremy@goop.org>

Xen requires pgds to be page-aligned, so make this a parameter which can be
set in the paravirt_ops structure.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Zachary Amsden <zach@vmware.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 arch/i386/kernel/paravirt.c |    1 +
 arch/i386/mm/init.c         |    2 +-
 include/asm-i386/paravirt.h |    5 ++++-
 include/asm-i386/pgtable.h  |    6 ++++++
 4 files changed, 12 insertions(+), 2 deletions(-)

diff -puN arch/i386/kernel/paravirt.c~xen-paravirt-allow-paravirt-backend-to-select-pgd-allocation-alignment arch/i386/kernel/paravirt.c
--- a/arch/i386/kernel/paravirt.c~xen-paravirt-allow-paravirt-backend-to-select-pgd-allocation-alignment
+++ a/arch/i386/kernel/paravirt.c
@@ -605,6 +605,7 @@ struct paravirt_ops paravirt_ops = {
 	.paravirt_enabled = 0,
 	.kernel_rpl = 0,
 	.shared_kernel_pmd = 1,	/* Only used when CONFIG_X86_PAE is set */
+	.pgd_alignment = sizeof(pgd_t) * PTRS_PER_PGD,
 
  	.patch = native_patch,
 	.banner = default_banner,
diff -puN arch/i386/mm/init.c~xen-paravirt-allow-paravirt-backend-to-select-pgd-allocation-alignment arch/i386/mm/init.c
--- a/arch/i386/mm/init.c~xen-paravirt-allow-paravirt-backend-to-select-pgd-allocation-alignment
+++ a/arch/i386/mm/init.c
@@ -729,7 +729,7 @@ void __init pgtable_cache_init(void)
 	}
 	pgd_cache = kmem_cache_create("pgd",
 				      PTRS_PER_PGD*sizeof(pgd_t),
-				      PTRS_PER_PGD*sizeof(pgd_t),
+				      PGD_ALIGNMENT,
 				      0, NULL, NULL);
 	if (!pgd_cache)
 		panic("pgtable_cache_init(): Cannot create pgd cache");
diff -puN include/asm-i386/paravirt.h~xen-paravirt-allow-paravirt-backend-to-select-pgd-allocation-alignment include/asm-i386/paravirt.h
--- a/include/asm-i386/paravirt.h~xen-paravirt-allow-paravirt-backend-to-select-pgd-allocation-alignment
+++ a/include/asm-i386/paravirt.h
@@ -33,9 +33,12 @@ struct tss_struct;
 struct mm_struct;
 struct paravirt_ops
 {
+ 	int paravirt_enabled;
 	unsigned int kernel_rpl;
+
 	int shared_kernel_pmd;
- 	int paravirt_enabled;
+	int pgd_alignment;
+
 	const char *name;
 
 	/*
diff -puN include/asm-i386/pgtable.h~xen-paravirt-allow-paravirt-backend-to-select-pgd-allocation-alignment include/asm-i386/pgtable.h
--- a/include/asm-i386/pgtable.h~xen-paravirt-allow-paravirt-backend-to-select-pgd-allocation-alignment
+++ a/include/asm-i386/pgtable.h
@@ -273,6 +273,12 @@ static inline void vmalloc_sync_all(void
 #define pte_update_defer(mm, addr, ptep)	do { } while (0)
 #endif
 
+#ifdef CONFIG_PARAVIRT
+#define PGD_ALIGNMENT	(paravirt_ops.pgd_alignment)
+#else
+#define PGD_ALIGNMENT	(sizeof(pgd_t) * PTRS_PER_PGD)
+#endif
+
 /*
  * We only update the dirty/accessed state if we set
  * the dirty bit by hand in the kernel, since the hardware
_