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[xen master] x86/mm: PGC_shadowed_pt is used by shadow code only
commit 4384d96c1cedfa4e388401be3a19ff50f8dce54b
Author: Jan Beulich <jbeulich@suse.com>
AuthorDate: Mon Dec 12 12:19:20 2022 +0100
Commit: Jan Beulich <jbeulich@suse.com>
CommitDate: Mon Dec 12 12:19:20 2022 +0100

x86/mm: PGC_shadowed_pt is used by shadow code only

By defining the constant to zero when !SHADOW_PAGING we give compilers
the chance to eliminate a little more dead code elsewhere in the tree.
Plus, as a minor benefit, the general reference count can be one bit
wider. (To simplify things, have PGC_shadowed_pt change places with
PGC_extra.)

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
xen/arch/x86/include/asm/mm.h | 20 ++++++++++++++------
1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/xen/arch/x86/include/asm/mm.h b/xen/arch/x86/include/asm/mm.h
index c4240a94d2..db29e3e205 100644
--- a/xen/arch/x86/include/asm/mm.h
+++ b/xen/arch/x86/include/asm/mm.h
@@ -70,9 +70,9 @@
/* Page is Xen heap? */
#define _PGC_xen_heap PG_shift(2)
#define PGC_xen_heap PG_mask(1, 2)
- /* Set when a page table page has been shadowed. */
-#define _PGC_shadowed_pt PG_shift(3)
-#define PGC_shadowed_pt PG_mask(1, 3)
+ /* Page is not reference counted */
+#define _PGC_extra PG_shift(3)
+#define PGC_extra PG_mask(1, 3)
/* Page is broken? */
#define _PGC_broken PG_shift(4)
#define PGC_broken PG_mask(1, 4)
@@ -83,12 +83,20 @@
#define PGC_state_offlined PG_mask(2, 6)
#define PGC_state_free PG_mask(3, 6)
#define page_state_is(pg, st) (((pg)->count_info&PGC_state) == PGC_state_##st)
-/* Page is not reference counted */
-#define _PGC_extra PG_shift(7)
-#define PGC_extra PG_mask(1, 7)
+#ifdef CONFIG_SHADOW_PAGING
+ /* Set when a page table page has been shadowed. */
+#define _PGC_shadowed_pt PG_shift(7)
+#define PGC_shadowed_pt PG_mask(1, 7)
+#else
+#define PGC_shadowed_pt 0
+#endif

/* Count of references to this frame. */
+#if PGC_shadowed_pt
#define PGC_count_width PG_shift(7)
+#else
+#define PGC_count_width PG_shift(6)
+#endif
#define PGC_count_mask ((1UL<<PGC_count_width)-1)

/*
--
generated by git-patchbot for /home/xen/git/xen.git#master