x86: provide build time option to support up to 123Tb of memory

As this requires growing struct page_info from 32 to 48 bytes as well
as shrinking the always accessible direct mapped memory range from 5Tb
to 3.5Tb, this isn't being introduced as a general or default enabled
feature.

For now setting "bigmem=y" implies "shadow-paging=n", as the shadow
paging code otherwise fails to build (see
http://lists.xenproject.org/archives/html/xen-devel/2015-01/msg03165.html).

A side effect of the change to x86's mm.h is that asm/mm.h may no
longer be included directly. Hence in the few places where this was done,
xen/mm.h is being substituted (indirectly in the hvm/mtrr.h case).

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/xen/arch/x86/Rules.mk
+++ b/xen/arch/x86/Rules.mk
@@ -32,7 +32,8 @@ x86 := y
 x86_32 := n
 x86_64 := y
 
-shadow-paging ?= y
+bigmem        ?= n
+shadow-paging ?= $(if $(filter y,$(bigmem)),n,y)
 
 CFLAGS += -mno-red-zone -mno-sse -fpic
 CFLAGS += -fno-asynchronous-unwind-tables
@@ -42,3 +43,4 @@ CFLAGS += -DGCC_HAS_VISIBILITY_ATTRIBUTE
 endif
 
 CFLAGS-$(shadow-paging) += -DCONFIG_SHADOW_PAGING
+CFLAGS-$(bigmem)        += -DCONFIG_BIGMEM
--- a/xen/arch/x86/hvm/mtrr.c
+++ b/xen/arch/x86/hvm/mtrr.c
@@ -18,13 +18,11 @@
  */
 
 #include <public/hvm/e820.h>
-#include <xen/types.h>
+#include <xen/domain_page.h>
 #include <asm/e820.h>
 #include <asm/iocap.h>
-#include <asm/mm.h>
 #include <asm/paging.h>
 #include <asm/p2m.h>
-#include <xen/domain_page.h>
 #include <asm/mtrr.h>
 #include <asm/hvm/support.h>
 #include <asm/hvm/cacheattr.h>
--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -386,8 +386,13 @@ static void __init setup_max_pdx(unsigne
     if ( max_pdx > FRAMETABLE_NR )
         max_pdx = FRAMETABLE_NR;
 
+    if ( max_pdx > MPT_VIRT_SIZE / sizeof(unsigned long) )
+        max_pdx = MPT_VIRT_SIZE / sizeof(unsigned long);
+
+#ifdef PAGE_LIST_NULL
     if ( max_pdx >= PAGE_LIST_NULL )
         max_pdx = PAGE_LIST_NULL - 1;
+#endif
 
     max_page = pdx_to_pfn(max_pdx - 1) + 1;
 }
--- a/xen/include/asm-x86/config.h
+++ b/xen/include/asm-x86/config.h
@@ -158,6 +158,7 @@ extern unsigned char boot_edid_info[128]
  *    High read-only compatibility machine-to-phys translation table.
  *  0xffff82d080000000 - 0xffff82d0bfffffff [1GB,   2^30 bytes, PML4:261]
  *    Xen text, static data, bss.
+#ifndef CONFIG_BIGMEM
  *  0xffff82d0c0000000 - 0xffff82dffbffffff [61GB - 64MB,       PML4:261]
  *    Reserved for future use.
  *  0xffff82dffc000000 - 0xffff82dfffffffff [64MB,  2^26 bytes, PML4:261]
@@ -166,6 +167,16 @@ extern unsigned char boot_edid_info[128]
  *    Page-frame information array.
  *  0xffff830000000000 - 0xffff87ffffffffff [5TB, 5*2^40 bytes, PML4:262-271]
  *    1:1 direct mapping of all physical memory.
+#else
+ *  0xffff82d0c0000000 - 0xffff82ffdfffffff [188.5GB,           PML4:261]
+ *    Reserved for future use.
+ *  0xffff82ffe0000000 - 0xffff82ffffffffff [512MB, 2^29 bytes, PML4:261]
+ *    Super-page information array.
+ *  0xffff830000000000 - 0xffff847fffffffff [1.5TB, 3*2^39 bytes, PML4:262-264]
+ *    Page-frame information array.
+ *  0xffff848000000000 - 0xffff87ffffffffff [3.5TB, 7*2^39 bytes, PML4:265-271]
+ *    1:1 direct mapping of all physical memory.
+#endif
  *  0xffff880000000000 - 0xffffffffffffffff [120TB,             PML4:272-511]
  *    PV: Guest-defined use.
  *  0xffff880000000000 - 0xffffff7fffffffff [119.5TB,           PML4:272-510]
@@ -234,21 +245,35 @@ extern unsigned char boot_edid_info[128]
 /* Slot 261: xen text, static data and bss (1GB). */
 #define XEN_VIRT_START          (HIRO_COMPAT_MPT_VIRT_END)
 #define XEN_VIRT_END            (XEN_VIRT_START + GB(1))
-/* Slot 261: superpage information array (64MB). */
+
+/* Slot 261: superpage information array (64MB or 512MB). */
 #define SPAGETABLE_VIRT_END     FRAMETABLE_VIRT_START
 #define SPAGETABLE_NR           (((FRAMETABLE_NR - 1) >> (SUPERPAGE_SHIFT - \
                                                           PAGE_SHIFT)) + 1)
 #define SPAGETABLE_SIZE         (SPAGETABLE_NR * sizeof(struct spage_info))
 #define SPAGETABLE_VIRT_START   ((SPAGETABLE_VIRT_END - SPAGETABLE_SIZE) & \
                                  (_AC(-1,UL) << SUPERPAGE_SHIFT))
+
+#ifndef CONFIG_BIGMEM
 /* Slot 261: page-frame information array (128GB). */
-#define FRAMETABLE_VIRT_END     DIRECTMAP_VIRT_START
 #define FRAMETABLE_SIZE         GB(128)
+#else
+/* Slot 262-264: page-frame information array (1.5TB). */
+#define FRAMETABLE_SIZE         GB(1536)
+#endif
+#define FRAMETABLE_VIRT_END     DIRECTMAP_VIRT_START
 #define FRAMETABLE_NR           (FRAMETABLE_SIZE / sizeof(*frame_table))
 #define FRAMETABLE_VIRT_START   (FRAMETABLE_VIRT_END - FRAMETABLE_SIZE)
+
+#ifndef CONFIG_BIGMEM
 /* Slot 262-271/510: A direct 1:1 mapping of all of physical memory. */
 #define DIRECTMAP_VIRT_START    (PML4_ADDR(262))
 #define DIRECTMAP_SIZE          (PML4_ENTRY_BYTES * (511 - 262))
+#else
+/* Slot 265-271/510: A direct 1:1 mapping of all of physical memory. */
+#define DIRECTMAP_VIRT_START    (PML4_ADDR(265))
+#define DIRECTMAP_SIZE          (PML4_ENTRY_BYTES * (511 - 265))
+#endif
 #define DIRECTMAP_VIRT_END      (DIRECTMAP_VIRT_START + DIRECTMAP_SIZE)
 
 #ifndef __ASSEMBLY__
--- a/xen/include/asm-x86/mm.h
+++ b/xen/include/asm-x86/mm.h
@@ -17,6 +17,7 @@
  */
 #define PFN_ORDER(_pfn) ((_pfn)->v.free.order)
 
+#ifndef CONFIG_BIGMEM
 /*
  * This definition is solely for the use in struct page_info (and
  * struct page_list_head), intended to allow easy adjustment once x86-64
@@ -30,6 +31,9 @@ struct page_list_entry
 {
     __pdx_t next, prev;
 };
+#else
+#define __pdx_t unsigned long
+#endif
 
 struct page_sharing_info;
 
--- a/xen/include/asm-x86/mtrr.h
+++ b/xen/include/asm-x86/mtrr.h
@@ -1,8 +1,7 @@
 #ifndef __ASM_X86_MTRR_H__
 #define __ASM_X86_MTRR_H__
 
-#include <xen/config.h>
-#include <asm/mm.h>
+#include <xen/mm.h>
 
 /* These are the region types. They match the architectural specification. */
 #define MTRR_TYPE_UNCACHABLE 0