# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1245317536 -3600
# Node ID baeb818cd2dc72053ed28353efa36b3a7e0e0227
# Parent cad6f60f050685d8dc824d5af53d23ad62e6faf6
x86-64: do not pass unmanageable amounts of memory to Dom0
Due to address space restrictions it is not possible to successfully
pass more than about 500Gb to a Linux Dom0 unless its kernel specifies
a non-default phys-to-machine map location via XEN_ELFNOTE_INIT_P2M.
For non-Linux Dom0 kernels I can't say whether the limit could be set
to close to 1Tb, but since passing such huge amounts of memory isn't
very useful anyway (and can be enforced via dom0_mem=3D), the patch
doesn't attempt to guess the kernel type and restricts the memory
amount in all cases.
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
---
arch/x86_64/kernel/head-xen.S | 3 --
arch/x86_64/kernel/setup-xen.c | 8 +++--
arch/x86_64/mm/init-xen.c | 41 ++++++++++++++++++++++++------
include/asm-x86_64/mach-xen/asm/pgtable.h | 4 +-
4 files changed, 40 insertions(+), 16 deletions(-)
diff -r cad6f60f0506 -r baeb818cd2dc arch/x86_64/kernel/head-xen.S
--- a/arch/x86_64/kernel/head-xen.S Thu Jun 18 10:24:18 2009 +0100
+++ b/arch/x86_64/kernel/head-xen.S Thu Jun 18 10:32:16 2009 +0100
@@ -76,9 +76,6 @@ NEXT_PAGE(level3_kernel_pgt)
*/
NEXT_PAGE(level3_user_pgt)
.fill 512,8,0
-
-NEXT_PAGE(level2_kernel_pgt)
- .fill 512,8,0
NEXT_PAGE(hypercall_page)
CFI_STARTPROC
diff -r cad6f60f0506 -r baeb818cd2dc arch/x86_64/kernel/setup-xen.c
--- a/arch/x86_64/kernel/setup-xen.c Thu Jun 18 10:24:18 2009 +0100
+++ b/arch/x86_64/kernel/setup-xen.c Thu Jun 18 10:32:16 2009 +0100
@@ -524,10 +524,12 @@ contig_initmem_init(unsigned long start_
panic("Cannot find bootmem map of size %ld\n",bootmap_size);
bootmap_size = init_bootmem(bootmap >> PAGE_SHIFT, end_pfn);
#ifdef CONFIG_XEN
- e820_bootmem_free(NODE_DATA(0), 0,
xen_start_info->nr_pages<<PAGE_SHIFT);
-#else
+ if (xen_start_info->nr_pages < end_pfn)
+ e820_bootmem_free(NODE_DATA(0), 0,
+ xen_start_info->nr_pages<<PAGE_SHIFT);
+ else
+#endif
e820_bootmem_free(NODE_DATA(0), 0, end_pfn << PAGE_SHIFT);
-#endif
reserve_bootmem(bootmap, bootmap_size);
}
#endif
diff -r cad6f60f0506 -r baeb818cd2dc arch/x86_64/mm/init-xen.c
--- a/arch/x86_64/mm/init-xen.c Thu Jun 18 10:24:18 2009 +0100
+++ b/arch/x86_64/mm/init-xen.c Thu Jun 18 10:32:16 2009 +0100
@@ -527,8 +527,6 @@ void __init xen_init_pt(void)
page = (unsigned long *)xen_start_info->pt_base;
addr = page[pgd_index(__START_KERNEL_map)];
addr_to_page(addr, page);
- addr = page[pud_index(__START_KERNEL_map)];
- addr_to_page(addr, page);
#if CONFIG_XEN_COMPAT <= 0x030002
/* On Xen 3.0.2 and older we may need to explicitly specify _PAGE_USER
@@ -539,7 +537,9 @@ void __init xen_init_pt(void)
/* Mess with the initial mapping of page 0. It's not needed. */
BUILD_BUG_ON(__START_KERNEL <= __START_KERNEL_map);
- addr = page[pmd_index(__START_KERNEL_map)];
+ addr = page[pud_index(__START_KERNEL_map)];
+ addr_to_page(addr, pg);
+ addr = pg[pmd_index(__START_KERNEL_map)];
addr_to_page(addr, pg);
pte.pte = pg[pte_index(__START_KERNEL_map)];
BUG_ON(!(pte.pte & _PAGE_PRESENT));
@@ -560,9 +560,10 @@ void __init xen_init_pt(void)
/* Construct mapping of initial pte page in our own directories. */
init_level4_pgt[pgd_index(__START_KERNEL_map)] =
__pgd(__pa_symbol(level3_kernel_pgt) | _PAGE_TABLE);
- level3_kernel_pgt[pud_index(__START_KERNEL_map)] =
- __pud(__pa_symbol(level2_kernel_pgt) | _PAGE_TABLE);
- memcpy(level2_kernel_pgt, page, PAGE_SIZE);
+ memcpy(level3_kernel_pgt + pud_index(__START_KERNEL_map),
+ page + pud_index(__START_KERNEL_map),
+ (PTRS_PER_PUD - pud_index(__START_KERNEL_map))
+ * sizeof(*level3_kernel_pgt));
__user_pgd(init_level4_pgt)[pgd_index(VSYSCALL_START)] =
__pgd(__pa_symbol(level3_user_pgt) | _PAGE_TABLE);
@@ -575,8 +576,6 @@ void __init xen_init_pt(void)
XENFEAT_writable_page_tables);
early_make_page_readonly(level3_user_pgt,
XENFEAT_writable_page_tables);
- early_make_page_readonly(level2_kernel_pgt,
- XENFEAT_writable_page_tables);
if (!xen_feature(XENFEAT_writable_page_tables)) {
xen_pgd_pin(__pa_symbol(init_level4_pgt));
@@ -608,6 +607,23 @@ static void __init extend_init_mapping(u
while (va < (__START_KERNEL_map
+ (start_pfn << PAGE_SHIFT)
+ tables_space)) {
+ if (!(pmd_index(va) | pte_index(va))) {
+ pud_t *pud;
+
+ page = (unsigned long *)init_level4_pgt;
+ addr = page[pgd_index(va)];
+ addr_to_page(addr, page);
+ pud = (pud_t *)&page[pud_index(va)];
+ if (pud_none(*pud)) {
+ page = alloc_static_page(&phys);
+ early_make_page_readonly(
+ page, XENFEAT_writable_page_tables);
+ set_pud(pud, __pud(phys | _KERNPG_TABLE));
+ } else {
+ addr = page[pud_index(va)];
+ addr_to_page(addr, page);
+ }
+ }
pmd = (pmd_t *)&page[pmd_index(va)];
if (pmd_none(*pmd)) {
pte_page = alloc_static_page(&phys);
@@ -630,6 +646,15 @@ static void __init extend_init_mapping(u
/* Finally, blow away any spurious initial mappings. */
while (1) {
+ if (!(pmd_index(va) | pte_index(va))) {
+ page = (unsigned long *)init_level4_pgt;
+ addr = page[pgd_index(va)];
+ addr_to_page(addr, page);
+ if (pud_none(((pud_t *)page)[pud_index(va)]))
+ break;
+ addr = page[pud_index(va)];
+ addr_to_page(addr, page);
+ }
pmd = (pmd_t *)&page[pmd_index(va)];
if (pmd_none(*pmd))
break;
diff -r cad6f60f0506 -r baeb818cd2dc include/asm-x86_64/mach-xen/asm/pgtable.h
--- a/include/asm-x86_64/mach-xen/asm/pgtable.h Thu Jun 18 10:24:18 2009 +0100
+++ b/include/asm-x86_64/mach-xen/asm/pgtable.h Thu Jun 18 10:32:16 2009 +0100
@@ -137,11 +137,11 @@ static inline void pgd_clear (pgd_t * pg
#define FIRST_USER_ADDRESS 0
#ifndef __ASSEMBLY__
-#define MAXMEM 0x3fffffffffffUL
+#define MAXMEM 0x6fffffffffUL
#define VMALLOC_START 0xffffc20000000000UL
#define VMALLOC_END 0xffffe1ffffffffffUL
#define MODULES_VADDR 0xffffffff88000000UL
-#define MODULES_END 0xfffffffffff00000UL
+#define MODULES_END 0xffffffffff000000UL
#define MODULES_LEN (MODULES_END - MODULES_VADDR)
#define _PAGE_BIT_PRESENT 0
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