[Lguest] [PATCH 17/25 -v2] introduce paravirt_release_pgd()

[Glauber de Oliveira Costa]

This patch introduces a new macro/function that informs a paravirt
guest when its page table is not more in use, and can be released.
In case we're not paravirt, just do nothing.

Signed-off-by: Glauber de Oliveira Costa <gcosta at redhat.com>
Signed-off-by: Steven Rostedt <rostedt at goodmis.org>
---
 include/asm-x86_64/pgalloc.h |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/include/asm-x86_64/pgalloc.h b/include/asm-x86_64/pgalloc.h
index b467be6..dbe1267 100644
--- a/include/asm-x86_64/pgalloc.h
+++ b/include/asm-x86_64/pgalloc.h
@@ -9,6 +9,12 @@
 #define QUICK_PGD 0	/* We preserve special mappings over free */
 #define QUICK_PT 1	/* Other page table pages that are zero on free */
 
+#ifdef CONFIG_PARAVIRT
+#include <asm/paravirt.h>
+#else
+#define paravirt_release_pgd(pgd) do { } while (0)
+#endif
+
 #define pmd_populate_kernel(mm, pmd, pte) \
 		set_pmd(pmd, __pmd(_PAGE_TABLE | __pa(pte)))
 #define pud_populate(mm, pud, pmd) \
@@ -100,6 +106,7 @@ static inline pgd_t *pgd_alloc(struct mm_struct *mm)
 static inline void pgd_free(pgd_t *pgd)
 {
 	BUG_ON((unsigned long)pgd & (PAGE_SIZE-1));
+	paravirt_release_pgd(pgd);
 	quicklist_free(QUICK_PGD, pgd_dtor, pgd);
 }
 
-- 
1.4.4.2