[PATCH v2 3/9] x86/p2m: suppress audit_p2m hook when possible

[Jan Beulich <jbeulich@xxxxxxxx>]

When P2M_AUDIT is false, it's unused, so instead of having a dangling
NULL pointer sit there, omit the field altogether.

Instead of adding "#if P2M_AUDIT && defined(CONFIG_HVM)" in even more
places, fold the latter part right into the definition of P2M_AUDIT.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
v2: Fix build with newer clang ("defined" may not be the result of a
    macro expansion).
---
I wonder if !NDEBUG wouldn't better be replaced by CONFIG_DEBUG.

--- a/xen/arch/x86/domctl.c
+++ b/xen/arch/x86/domctl.c
@@ -1012,7 +1012,7 @@ long arch_do_domctl(
         break;
 #endif
 
-#if P2M_AUDIT && defined(CONFIG_HVM)
+#if P2M_AUDIT
     case XEN_DOMCTL_audit_p2m:
         if ( d == currd )
             ret = -EPERM;
--- a/xen/arch/x86/mm/p2m-ept.c
+++ b/xen/arch/x86/mm/p2m-ept.c
@@ -1260,7 +1260,9 @@ int ept_p2m_init(struct p2m_domain *p2m)
     p2m->change_entry_type_global = ept_change_entry_type_global;
     p2m->change_entry_type_range = ept_change_entry_type_range;
     p2m->memory_type_changed = ept_memory_type_changed;
+#if P2M_AUDIT
     p2m->audit_p2m = NULL;
+#endif
     p2m->tlb_flush = ept_tlb_flush;
 
     /* Set the memory type used when accessing EPT paging structures. */
--- a/xen/arch/x86/mm/p2m-pt.c
+++ b/xen/arch/x86/mm/p2m-pt.c
@@ -971,8 +971,8 @@ static int p2m_pt_change_entry_type_rang
     return err;
 }
 
-#if P2M_AUDIT && defined(CONFIG_HVM)
-long p2m_pt_audit_p2m(struct p2m_domain *p2m)
+#if P2M_AUDIT
+static long p2m_pt_audit_p2m(struct p2m_domain *p2m)
 {
     unsigned long entry_count = 0, pmbad = 0;
     unsigned long mfn, gfn, m2pfn;
@@ -1120,8 +1120,6 @@ long p2m_pt_audit_p2m(struct p2m_domain
 
     return pmbad;
 }
-#else
-# define p2m_pt_audit_p2m NULL
 #endif /* P2M_AUDIT */
 
 /* Set up the p2m function pointers for pagetable format */
@@ -1141,8 +1139,6 @@ void p2m_pt_init(struct p2m_domain *p2m)
 
 #if P2M_AUDIT
     p2m->audit_p2m = p2m_pt_audit_p2m;
-#else
-    p2m->audit_p2m = NULL;
 #endif
 }
 
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -2435,7 +2435,7 @@ int p2m_altp2m_propagate_change(struct d
 
 /*** Audit ***/
 
-#if P2M_AUDIT && defined(CONFIG_HVM)
+#if P2M_AUDIT
 void audit_p2m(struct domain *d,
                uint64_t *orphans,
                 uint64_t *m2p_bad,
--- a/xen/include/asm-x86/p2m.h
+++ b/xen/include/asm-x86/p2m.h
@@ -31,6 +31,14 @@
 #include <asm/mem_sharing.h>
 #include <asm/page.h>    /* for pagetable_t */
 
+/* Debugging and auditing of the P2M code? */
+#if !defined(NDEBUG) && defined(CONFIG_HVM)
+#define P2M_AUDIT     1
+#else
+#define P2M_AUDIT     0
+#endif
+#define P2M_DEBUGGING 0
+
 extern bool_t opt_hap_1gb, opt_hap_2mb;
 
 /*
@@ -268,7 +276,9 @@ struct p2m_domain {
     int                (*write_p2m_entry)(struct p2m_domain *p2m,
                                           unsigned long gfn, l1_pgentry_t *p,
                                           l1_pgentry_t new, unsigned int 
level);
+#if P2M_AUDIT
     long               (*audit_p2m)(struct p2m_domain *p2m);
+#endif
 
     /*
      * P2M updates may require TLBs to be flushed (invalidated).
@@ -758,14 +768,6 @@ extern void p2m_pt_init(struct p2m_domai
 void *map_domain_gfn(struct p2m_domain *p2m, gfn_t gfn, mfn_t *mfn,
                      p2m_query_t q, uint32_t *pfec);
 
-/* Debugging and auditing of the P2M code? */
-#ifndef NDEBUG
-#define P2M_AUDIT     1
-#else
-#define P2M_AUDIT     0
-#endif
-#define P2M_DEBUGGING 0
-
 #if P2M_AUDIT
 extern void audit_p2m(struct domain *d,
                       uint64_t *orphans,