[Xen-devel] [PATCH for-4.5 v8 03/19] xen: Relocate p2m_access_t into common and swap the order

[Tamas K Lengyel <tklengyel@xxxxxxxxxxxxx>]

We swap the order of the enum of types n ... rwx, as to have rwx at 0, which is
the default setting when mem_access is not in use. This has performance 
benefits for
non-memaccess paths, as now comparison is to 0 when checking if memaccess is in 
use,
which is often faster.

We fix one location in nested_hap where the order of the enum made a difference.

Signed-off-by: Tamas K Lengyel <tklengyel@xxxxxxxxxxxxx>
Acked-by: Tim Deegan <tim@xxxxxxx>
---
 xen/arch/x86/mm/hap/nested_hap.c |  2 +-
 xen/include/asm-x86/p2m.h        | 28 ----------------------------
 xen/include/xen/p2m-common.h     | 29 +++++++++++++++++++++++++++++
 3 files changed, 30 insertions(+), 29 deletions(-)

diff --git a/xen/arch/x86/mm/hap/nested_hap.c b/xen/arch/x86/mm/hap/nested_hap.c
index a4bb835..9c1ec11 100644
--- a/xen/arch/x86/mm/hap/nested_hap.c
+++ b/xen/arch/x86/mm/hap/nested_hap.c
@@ -264,7 +264,7 @@ nestedhvm_hap_nested_page_fault(struct vcpu *v, paddr_t 
*L2_gpa,
 
     switch ( p2ma_10 )
     {
-    case p2m_access_n ... p2m_access_rwx:
+    case p2m_access_rwx ... p2m_access_n:
         break;
     case p2m_access_rx2rw:
         p2ma_10 = p2m_access_rx;
diff --git a/xen/include/asm-x86/p2m.h b/xen/include/asm-x86/p2m.h
index bae669e..a2a6289 100644
--- a/xen/include/asm-x86/p2m.h
+++ b/xen/include/asm-x86/p2m.h
@@ -74,34 +74,6 @@ typedef enum {
     p2m_map_foreign  = 14,        /* ram pages from foreign domain */
 } p2m_type_t;
 
-/*
- * Additional access types, which are used to further restrict
- * the permissions given my the p2m_type_t memory type.  Violations
- * caused by p2m_access_t restrictions are sent to the mem_event
- * interface.
- *
- * The access permissions are soft state: when any ambigious change of page
- * type or use occurs, or when pages are flushed, swapped, or at any other
- * convenient type, the access permissions can get reset to the p2m_domain
- * default.
- */
-typedef enum {
-    p2m_access_n     = 0, /* No access permissions allowed */
-    p2m_access_r     = 1,
-    p2m_access_w     = 2, 
-    p2m_access_rw    = 3,
-    p2m_access_x     = 4, 
-    p2m_access_rx    = 5,
-    p2m_access_wx    = 6, 
-    p2m_access_rwx   = 7,
-    p2m_access_rx2rw = 8, /* Special: page goes from RX to RW on write */
-    p2m_access_n2rwx = 9, /* Special: page goes from N to RWX on access, *
-                           * generates an event but does not pause the
-                           * vcpu */
-
-    /* NOTE: Assumed to be only 4 bits right now */
-} p2m_access_t;
-
 /* Modifiers to the query */
 typedef unsigned int p2m_query_t;
 #define P2M_ALLOC    (1u<<0)   /* Populate PoD and paged-out entries */
diff --git a/xen/include/xen/p2m-common.h b/xen/include/xen/p2m-common.h
index 9f1b771..787fc43 100644
--- a/xen/include/xen/p2m-common.h
+++ b/xen/include/xen/p2m-common.h
@@ -1,6 +1,35 @@
 #ifndef _XEN_P2M_COMMON_H
 #define _XEN_P2M_COMMON_H
 
+/*
+ * Additional access types, which are used to further restrict
+ * the permissions given my the p2m_type_t memory type.  Violations
+ * caused by p2m_access_t restrictions are sent to the mem_event
+ * interface.
+ *
+ * The access permissions are soft state: when any ambiguous change of page
+ * type or use occurs, or when pages are flushed, swapped, or at any other
+ * convenient type, the access permissions can get reset to the p2m_domain
+ * default.
+ */
+typedef enum {
+    p2m_access_rwx   = 0, /* The default access type when not used. */
+    p2m_access_wx    = 1,
+    p2m_access_rx    = 2,
+    p2m_access_x     = 3,
+    p2m_access_rw    = 4,
+    p2m_access_w     = 5,
+    p2m_access_r     = 6,
+    p2m_access_n     = 7, /* No access allowed. */
+
+    p2m_access_rx2rw = 8, /* Special: page goes from RX to RW on write */
+    p2m_access_n2rwx = 9, /* Special: page goes from N to RWX on access, *
+                           * generates an event but does not pause the
+                           * vcpu */
+
+    /* NOTE: Assumed to be only 4 bits right now on x86. */
+} p2m_access_t;
+
 /* Map MMIO regions in the p2m: start_gfn and nr describe the range in
  *  * the guest physical address space to map, starting from the machine
  *   * frame number mfn. */
-- 
2.1.0


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