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authorIan Campbell <ian.campbell@citrix.com>2010-11-24 12:09:41 +0000
committerKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2010-11-24 12:07:44 -0500
commit5b5c1af104ab5adec1be9dcb4c787492d83d8d83 (patch)
tree38292f2f54e581c341e63fe0eeb837907931b753
parente53beacd23d9cb47590da6a7a7f6d417b941a994 (diff)
downloadlinux-linaro-android-5b5c1af104ab5adec1be9dcb4c787492d83d8d83.tar.gz
xen: x86/32: perform initial startup on initial_page_table
Only make swapper_pg_dir readonly and pinned when generic x86 architecture code (which also starts on initial_page_table) switches to it. This helps ensure that the generic setup paths work on Xen unmodified. In particular clone_pgd_range writes directly to the destination pgd entries and is used to initialise swapper_pg_dir so we need to ensure that it remains writeable until the last possible moment during bring up. This is complicated slightly by the need to avoid sharing kernel PMD entries when running under Xen, therefore the Xen implementation must make a copy of the kernel PMD (which is otherwise referred to by both intial_page_table and swapper_pg_dir) before switching to swapper_pg_dir. Signed-off-by: Ian Campbell <ian.campbell@citrix.com> Tested-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: H. Peter Anvin <hpa@linux.intel.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
-rw-r--r--arch/x86/xen/enlighten.c2
-rw-r--r--arch/x86/xen/mmu.c69
2 files changed, 56 insertions, 15 deletions
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 235c0f4d386..ff82909801b 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1191,8 +1191,6 @@ asmlinkage void __init xen_start_kernel(void)
/* Allocate and initialize top and mid mfn levels for p2m structure */
xen_build_mfn_list_list();
- init_mm.pgd = pgd;
-
/* keep using Xen gdt for now; no urgent need to change it */
#ifdef CONFIG_X86_32
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 21ed8d7f75a..c9cf23e1744 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -2119,44 +2119,83 @@ __init pgd_t *xen_setup_kernel_pagetable(pgd_t *pgd,
return pgd;
}
#else /* !CONFIG_X86_64 */
-static RESERVE_BRK_ARRAY(pmd_t, level2_kernel_pgt, PTRS_PER_PMD);
+static RESERVE_BRK_ARRAY(pmd_t, initial_kernel_pmd, PTRS_PER_PMD);
+static RESERVE_BRK_ARRAY(pmd_t, swapper_kernel_pmd, PTRS_PER_PMD);
+
+static __init void xen_write_cr3_init(unsigned long cr3)
+{
+ unsigned long pfn = PFN_DOWN(__pa(swapper_pg_dir));
+
+ BUG_ON(read_cr3() != __pa(initial_page_table));
+ BUG_ON(cr3 != __pa(swapper_pg_dir));
+
+ /*
+ * We are switching to swapper_pg_dir for the first time (from
+ * initial_page_table) and therefore need to mark that page
+ * read-only and then pin it.
+ *
+ * Xen disallows sharing of kernel PMDs for PAE
+ * guests. Therefore we must copy the kernel PMD from
+ * initial_page_table into a new kernel PMD to be used in
+ * swapper_pg_dir.
+ */
+ swapper_kernel_pmd =
+ extend_brk(sizeof(pmd_t) * PTRS_PER_PMD, PAGE_SIZE);
+ memcpy(swapper_kernel_pmd, initial_kernel_pmd,
+ sizeof(pmd_t) * PTRS_PER_PMD);
+ swapper_pg_dir[KERNEL_PGD_BOUNDARY] =
+ __pgd(__pa(swapper_kernel_pmd) | _PAGE_PRESENT);
+ set_page_prot(swapper_kernel_pmd, PAGE_KERNEL_RO);
+
+ set_page_prot(swapper_pg_dir, PAGE_KERNEL_RO);
+ xen_write_cr3(cr3);
+ pin_pagetable_pfn(MMUEXT_PIN_L3_TABLE, pfn);
+
+ pin_pagetable_pfn(MMUEXT_UNPIN_TABLE,
+ PFN_DOWN(__pa(initial_page_table)));
+ set_page_prot(initial_page_table, PAGE_KERNEL);
+ set_page_prot(initial_kernel_pmd, PAGE_KERNEL);
+
+ pv_mmu_ops.write_cr3 = &xen_write_cr3;
+}
__init pgd_t *xen_setup_kernel_pagetable(pgd_t *pgd,
unsigned long max_pfn)
{
pmd_t *kernel_pmd;
- level2_kernel_pgt = extend_brk(sizeof(pmd_t) * PTRS_PER_PMD, PAGE_SIZE);
+ initial_kernel_pmd =
+ extend_brk(sizeof(pmd_t) * PTRS_PER_PMD, PAGE_SIZE);
max_pfn_mapped = PFN_DOWN(__pa(xen_start_info->pt_base) +
xen_start_info->nr_pt_frames * PAGE_SIZE +
512*1024);
kernel_pmd = m2v(pgd[KERNEL_PGD_BOUNDARY].pgd);
- memcpy(level2_kernel_pgt, kernel_pmd, sizeof(pmd_t) * PTRS_PER_PMD);
+ memcpy(initial_kernel_pmd, kernel_pmd, sizeof(pmd_t) * PTRS_PER_PMD);
- xen_map_identity_early(level2_kernel_pgt, max_pfn);
+ xen_map_identity_early(initial_kernel_pmd, max_pfn);
- memcpy(swapper_pg_dir, pgd, sizeof(pgd_t) * PTRS_PER_PGD);
- set_pgd(&swapper_pg_dir[KERNEL_PGD_BOUNDARY],
- __pgd(__pa(level2_kernel_pgt) | _PAGE_PRESENT));
+ memcpy(initial_page_table, pgd, sizeof(pgd_t) * PTRS_PER_PGD);
+ initial_page_table[KERNEL_PGD_BOUNDARY] =
+ __pgd(__pa(initial_kernel_pmd) | _PAGE_PRESENT);
- set_page_prot(level2_kernel_pgt, PAGE_KERNEL_RO);
- set_page_prot(swapper_pg_dir, PAGE_KERNEL_RO);
+ set_page_prot(initial_kernel_pmd, PAGE_KERNEL_RO);
+ set_page_prot(initial_page_table, PAGE_KERNEL_RO);
set_page_prot(empty_zero_page, PAGE_KERNEL_RO);
pin_pagetable_pfn(MMUEXT_UNPIN_TABLE, PFN_DOWN(__pa(pgd)));
- xen_write_cr3(__pa(swapper_pg_dir));
-
- pin_pagetable_pfn(MMUEXT_PIN_L3_TABLE, PFN_DOWN(__pa(swapper_pg_dir)));
+ pin_pagetable_pfn(MMUEXT_PIN_L3_TABLE,
+ PFN_DOWN(__pa(initial_page_table)));
+ xen_write_cr3(__pa(initial_page_table));
memblock_x86_reserve_range(__pa(xen_start_info->pt_base),
__pa(xen_start_info->pt_base +
xen_start_info->nr_pt_frames * PAGE_SIZE),
"XEN PAGETABLES");
- return swapper_pg_dir;
+ return initial_page_table;
}
#endif /* CONFIG_X86_64 */
@@ -2290,7 +2329,11 @@ static const struct pv_mmu_ops xen_mmu_ops __initdata = {
.write_cr2 = xen_write_cr2,
.read_cr3 = xen_read_cr3,
+#ifdef CONFIG_X86_32
+ .write_cr3 = xen_write_cr3_init,
+#else
.write_cr3 = xen_write_cr3,
+#endif
.flush_tlb_user = xen_flush_tlb,
.flush_tlb_kernel = xen_flush_tlb,