xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

xen: Cope with unmapped pages when initializing kernel pagetable

Browse Source 
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>
This commit is contained in:
Jeremy Fitzhardinge
2010-10-13 16:02:24 -07:00
committed by H. Peter Anvin
parent c7fc2de0c8
commit fef5ba7979
3 changed files with 24 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
arch/x86/include/asm/io.h
View File

@@ -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