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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/include/asm/io.h
parentc7fc2de0c83dbd2eaf759c5cd0e2b9cf1eb4df3a (diff)
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/include/asm/io.h')
-rw-r--r--arch/x86/include/asm/io.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h
index 30a3e977612..66aee6c4123 100644
--- a/arch/x86/include/asm/io.h
+++ b/arch/x86/include/asm/io.h
@@ -348,6 +348,7 @@ extern void __iomem *early_memremap(resource_size_t phys_addr,
unsigned long size);
extern void early_iounmap(void __iomem *addr, unsigned long size);
extern void fixup_early_ioremap(void);
+extern bool is_early_ioremap_ptep(pte_t *ptep);
#define IO_SPACE_LIMIT 0xffff