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authorJeremy Fitzhardinge <jeremy@goop.org>2007-05-02 19:27:13 +0200
committerAndi Kleen <andi@basil.nowhere.org>2007-05-02 19:27:13 +0200
commit5311ab62cdc7788784971ed816ce85e926f3e994 (patch)
tree08ceda3c1bbdc6c403107f5329d775c772b752ce /include
parent90caccb9758e88db68a69553689baee38254287b (diff)
[PATCH] i386: PARAVIRT: Allow paravirt backend to choose kernel PMD sharing
Normally when running in PAE mode, the 4th PMD maps the kernel address space, which can be shared among all processes (since they all need the same kernel mappings). Xen, however, does not allow guests to have the kernel pmd shared between page tables, so parameterize pgtable.c to allow both modes of operation. There are several side-effects of this. One is that vmalloc will update the kernel address space mappings, and those updates need to be propagated into all processes if the kernel mappings are not intrinsically shared. In the non-PAE case, this is done by maintaining a pgd_list of all processes; this list is used when all process pagetables must be updated. pgd_list is threaded via otherwise unused entries in the page structure for the pgd, which means that the pgd must be page-sized for this to work. Normally the PAE pgd is only 4x64 byte entries large, but Xen requires the PAE pgd to page aligned anyway, so this patch forces the pgd to be page aligned+sized when the kernel pmd is unshared, to accomodate both these requirements. Also, since there may be several distinct kernel pmds (if the user/kernel split is below 3G), there's no point in allocating them from a slab cache; they're just allocated with get_free_page and initialized appropriately. (Of course the could be cached if there is just a single kernel pmd - which is the default with a 3G user/kernel split - but it doesn't seem worthwhile to add yet another case into this code). [ Many thanks to wli for review comments. ] Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com> Signed-off-by: William Lee Irwin III <wli@holomorphy.com> Signed-off-by: Andi Kleen <ak@suse.de> Cc: Zachary Amsden <zach@vmware.com> Cc: Christoph Lameter <clameter@sgi.com> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/asm-i386/paravirt.h1
-rw-r--r--include/asm-i386/pgtable-2level-defs.h2
-rw-r--r--include/asm-i386/pgtable-2level.h2
-rw-r--r--include/asm-i386/pgtable-3level-defs.h6
-rw-r--r--include/asm-i386/pgtable-3level.h2
-rw-r--r--include/asm-i386/pgtable.h2
6 files changed, 11 insertions, 4 deletions
diff --git a/include/asm-i386/paravirt.h b/include/asm-i386/paravirt.h
index c49b44cdd8e..f93599dc775 100644
--- a/include/asm-i386/paravirt.h
+++ b/include/asm-i386/paravirt.h
@@ -35,6 +35,7 @@ struct desc_struct;
struct paravirt_ops
{
unsigned int kernel_rpl;
+ int shared_kernel_pmd;
int paravirt_enabled;
const char *name;
diff --git a/include/asm-i386/pgtable-2level-defs.h b/include/asm-i386/pgtable-2level-defs.h
index 02518079f81..0f71c9f13da 100644
--- a/include/asm-i386/pgtable-2level-defs.h
+++ b/include/asm-i386/pgtable-2level-defs.h
@@ -1,6 +1,8 @@
#ifndef _I386_PGTABLE_2LEVEL_DEFS_H
#define _I386_PGTABLE_2LEVEL_DEFS_H
+#define SHARED_KERNEL_PMD 0
+
/*
* traditional i386 two-level paging structure:
*/
diff --git a/include/asm-i386/pgtable-2level.h b/include/asm-i386/pgtable-2level.h
index 043a2bcfa86..781fe4bcc96 100644
--- a/include/asm-i386/pgtable-2level.h
+++ b/include/asm-i386/pgtable-2level.h
@@ -82,6 +82,4 @@ static inline int pte_exec_kernel(pte_t pte)
#define __pte_to_swp_entry(pte) ((swp_entry_t) { (pte).pte_low })
#define __swp_entry_to_pte(x) ((pte_t) { (x).val })
-void vmalloc_sync_all(void);
-
#endif /* _I386_PGTABLE_2LEVEL_H */
diff --git a/include/asm-i386/pgtable-3level-defs.h b/include/asm-i386/pgtable-3level-defs.h
index eb3a1ea8867..c0df89f66e8 100644
--- a/include/asm-i386/pgtable-3level-defs.h
+++ b/include/asm-i386/pgtable-3level-defs.h
@@ -1,6 +1,12 @@
#ifndef _I386_PGTABLE_3LEVEL_DEFS_H
#define _I386_PGTABLE_3LEVEL_DEFS_H
+#ifdef CONFIG_PARAVIRT
+#define SHARED_KERNEL_PMD (paravirt_ops.shared_kernel_pmd)
+#else
+#define SHARED_KERNEL_PMD 1
+#endif
+
/*
* PGDIR_SHIFT determines what a top-level page table entry can map
*/
diff --git a/include/asm-i386/pgtable-3level.h b/include/asm-i386/pgtable-3level.h
index be6017f37a9..664bfee5a2f 100644
--- a/include/asm-i386/pgtable-3level.h
+++ b/include/asm-i386/pgtable-3level.h
@@ -200,6 +200,4 @@ static inline pmd_t pfn_pmd(unsigned long page_nr, pgprot_t pgprot)
#define __pmd_free_tlb(tlb, x) do { } while (0)
-#define vmalloc_sync_all() ((void)0)
-
#endif /* _I386_PGTABLE_3LEVEL_H */
diff --git a/include/asm-i386/pgtable.h b/include/asm-i386/pgtable.h
index 0790ad6ed44..5b88a6a1278 100644
--- a/include/asm-i386/pgtable.h
+++ b/include/asm-i386/pgtable.h
@@ -243,6 +243,8 @@ static inline pte_t pte_mkyoung(pte_t pte) { (pte).pte_low |= _PAGE_ACCESSED; re
static inline pte_t pte_mkwrite(pte_t pte) { (pte).pte_low |= _PAGE_RW; return pte; }
static inline pte_t pte_mkhuge(pte_t pte) { (pte).pte_low |= _PAGE_PSE; return pte; }
+extern void vmalloc_sync_all(void);
+
#ifdef CONFIG_X86_PAE
# include <asm/pgtable-3level.h>
#else