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authorJeremy Fitzhardinge <jeremy@goop.org>2010-10-13 16:02:24 -0700
committerH. Peter Anvin <hpa@linux.intel.com>2010-10-13 16:07:13 -0700
commitfef5ba797991f9335bcfc295942b684f9bf613a1 (patch)
tree25aa49f656def959f5380d1320ebbf1f469e3c07 /arch/x86/xen/mmu.c
parentc7fc2de0c83dbd2eaf759c5cd0e2b9cf1eb4df3a (diff)
downloadlinux-linaro-android-fef5ba797991f9335bcfc295942b684f9bf613a1.tar.gz
xen: Cope with unmapped pages when initializing kernel pagetable
Xen requires that all pages containing pagetable entries to be mapped read-only. If pages used for the initial pagetable are already mapped then we can change the mapping to RO. However, if they are initially unmapped, we need to make sure that when they are later mapped, they are also mapped RO. We do this by knowing that the kernel pagetable memory is pre-allocated in the range e820_table_start - e820_table_end, so any pfn within this range should be mapped read-only. However, the pagetable setup code early_ioremaps the pages to write their entries, so we must make sure that mappings created in the early_ioremap fixmap area are mapped RW. (Those mappings are removed before the pages are presented to Xen as pagetable pages.) Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> LKML-Reference: <4CB63A80.8060702@goop.org> Cc: Yinghai Lu <yinghai@kernel.org> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Diffstat (limited to 'arch/x86/xen/mmu.c')
-rw-r--r--arch/x86/xen/mmu.c26
1 files changed, 18 insertions, 8 deletions
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 4fe04ac0bae..7d55e9ee3a7 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -56,6 +56,7 @@
#include <asm/e820.h>
#include <asm/linkage.h>
#include <asm/page.h>
+#include <asm/init.h>
#include <asm/xen/hypercall.h>
#include <asm/xen/hypervisor.h>
@@ -360,7 +361,8 @@ void make_lowmem_page_readonly(void *vaddr)
unsigned int level;
pte = lookup_address(address, &level);
- BUG_ON(pte == NULL);
+ if (pte == NULL)
+ return; /* vaddr missing */
ptev = pte_wrprotect(*pte);
@@ -375,7 +377,8 @@ void make_lowmem_page_readwrite(void *vaddr)
unsigned int level;
pte = lookup_address(address, &level);
- BUG_ON(pte == NULL);
+ if (pte == NULL)
+ return; /* vaddr missing */
ptev = pte_mkwrite(*pte);
@@ -1509,13 +1512,25 @@ static void xen_pgd_free(struct mm_struct *mm, pgd_t *pgd)
#endif
}
-#ifdef CONFIG_X86_32
static __init pte_t mask_rw_pte(pte_t *ptep, pte_t pte)
{
+ unsigned long pfn = pte_pfn(pte);
+
+#ifdef CONFIG_X86_32
/* If there's an existing pte, then don't allow _PAGE_RW to be set */
if (pte_val_ma(*ptep) & _PAGE_PRESENT)
pte = __pte_ma(((pte_val_ma(*ptep) & _PAGE_RW) | ~_PAGE_RW) &
pte_val_ma(pte));
+#endif
+
+ /*
+ * If the new pfn is within the range of the newly allocated
+ * kernel pagetable, and it isn't being mapped into an
+ * early_ioremap fixmap slot, make sure it is RO.
+ */
+ if (!is_early_ioremap_ptep(ptep) &&
+ pfn >= e820_table_start && pfn < e820_table_end)
+ pte = pte_wrprotect(pte);
return pte;
}
@@ -1528,7 +1543,6 @@ static __init void xen_set_pte_init(pte_t *ptep, pte_t pte)
xen_set_pte(ptep, pte);
}
-#endif
static void pin_pagetable_pfn(unsigned cmd, unsigned long pfn)
{
@@ -1973,11 +1987,7 @@ static const struct pv_mmu_ops xen_mmu_ops __initdata = {
.alloc_pmd_clone = paravirt_nop,
.release_pmd = xen_release_pmd_init,
-#ifdef CONFIG_X86_64
- .set_pte = xen_set_pte,
-#else
.set_pte = xen_set_pte_init,
-#endif
.set_pte_at = xen_set_pte_at,
.set_pmd = xen_set_pmd_hyper,