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[PATCH] paravirt: optimize ptep establish for pae

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The ptep_establish macro is only used on user-level PTEs, for P->P mapping
changes.  Since these always happen under protection of the pagetable lock,
the strong synchronization of a 64-bit cmpxchg is not needed, in fact, not
even a lock prefix needs to be used.  We can simply instead clear the P-bit,
followed by a normal set.  The write ordering is still important to avoid the
possibility of the TLB snooping a partially written PTE and getting a bad
mapping installed.

Signed-off-by: Zachary Amsden <zach@vmware.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Zachary Amsden
2006-09-30 23:29:36 -07:00
committed by Linus Torvalds
parent 23002d88be
commit d6d861e3c9
3 changed files with 27 additions and 0 deletions
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1
include/asm-i386/pgtable-2level.h
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@@ -16,6 +16,7 @@
#define set_pte(pteptr, pteval) (*(pteptr) = pteval)
#define set_pte_at(mm,addr,ptep,pteval) set_pte(ptep,pteval)
#define set_pte_atomic(pteptr, pteval) set_pte(pteptr,pteval)
#define set_pte_present(mm,addr,ptep,pteval) set_pte_at(mm,addr,ptep,pteval)
#define set_pmd(pmdptr, pmdval) (*(pmdptr) = (pmdval))
#define pte_clear(mm,addr,xp) do { set_pte_at(mm, addr, xp, __pte(0)); } while (0)