x86/shadow: the guess_wrmap() hook is needed for HVM only

sh_remove_write_access() bails early for !external guests, and hence its
building and thus the need for the hook can be suppressed altogether in
!HVM configs.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Tim Deegan <tim@xen.org>

xen/arch/x86/mm/shadow/common.c

@@ -1769,6 +1769,7 @@ static inline void trace_shadow_wrmap_bf(mfn_t gmfn)
     }
 }
 
+#ifdef CONFIG_HVM
 /**************************************************************************/
 /* Remove all writeable mappings of a guest frame from the shadow tables
  * Returns non-zero if we need to flush TLBs.
@@ -2000,6 +2001,7 @@ int sh_remove_write_access(struct domain *d, mfn_t gmfn,
     /* We killed at least one writeable mapping, so must flush TLBs. */
     return 1;
 }
+#endif /* CONFIG_HVM */
 
 #if (SHADOW_OPTIMIZATIONS & SHOPT_OUT_OF_SYNC)
 static int sh_remove_write_access_from_sl1p(struct domain *d, mfn_t gmfn,

xen/arch/x86/mm/shadow/multi.c

@@ -4212,7 +4212,7 @@ int sh_rm_write_access_from_sl1p(struct domain *d, mfn_t gmfn,
 }
 #endif /* OOS */
 
-#if SHADOW_OPTIMIZATIONS & SHOPT_WRITABLE_HEURISTIC
+#if defined(CONFIG_HVM) && (SHADOW_OPTIMIZATIONS & SHOPT_WRITABLE_HEURISTIC)
 static int sh_guess_wrmap(struct vcpu *v, unsigned long vaddr, mfn_t gmfn)
 /* Look up this vaddr in the current shadow and see if it's a writeable
  * mapping of this gmfn.  If so, remove it.  Returns 1 if it worked. */
@@ -4884,10 +4884,10 @@ const struct paging_mode sh_paging_mode = {
 #ifdef CONFIG_HVM
     .shadow.make_monitor_table     = sh_make_monitor_table,
     .shadow.destroy_monitor_table  = sh_destroy_monitor_table,
-#endif
 #if SHADOW_OPTIMIZATIONS & SHOPT_WRITABLE_HEURISTIC
     .shadow.guess_wrmap            = sh_guess_wrmap,
 #endif
+#endif /* CONFIG_HVM */
     .shadow.pagetable_dying        = sh_pagetable_dying,
     .shadow.trace_emul_write_val   = trace_emulate_write_val,
     .shadow.shadow_levels          = SHADOW_PAGING_LEVELS,

xen/arch/x86/mm/shadow/private.h

@@ -359,6 +359,7 @@ void sh_install_xen_entries_in_l4(struct domain *, mfn_t gl4mfn, mfn_t sl4mfn);
 /* Update the shadows in response to a pagetable write from Xen */
 int sh_validate_guest_entry(struct vcpu *v, mfn_t gmfn, void *entry, u32 size);
 
+#ifdef CONFIG_HVM
 /* Remove all writeable mappings of a guest frame from the shadows.
  * Returns non-zero if we need to flush TLBs.
  * level and fault_addr desribe how we found this to be a pagetable;
@@ -366,6 +367,15 @@ int sh_validate_guest_entry(struct vcpu *v, mfn_t gmfn, void *entry, u32 size);
 extern int sh_remove_write_access(struct domain *d, mfn_t readonly_mfn,
                                   unsigned int level,
                                   unsigned long fault_addr);
+#else
+static inline int sh_remove_write_access(struct domain *d, mfn_t readonly_mfn,
+                                         unsigned int level,
+                                         unsigned long fault_addr)
+{
+    ASSERT(!shadow_mode_refcounts(d));
+    return 0;
+}
+#endif
 
 /* Functions that atomically write PT/P2M entries and update state */
 int shadow_write_p2m_entry(struct p2m_domain *p2m, unsigned long gfn,

xen/include/asm-x86/paging.h

@@ -105,9 +105,9 @@ struct shadow_paging_mode {
 #ifdef CONFIG_HVM
     mfn_t         (*make_monitor_table    )(struct vcpu *v);
     void          (*destroy_monitor_table )(struct vcpu *v, mfn_t mmfn);
-#endif
     int           (*guess_wrmap           )(struct vcpu *v, 
                                             unsigned long vaddr, mfn_t gmfn);
+#endif
     void          (*pagetable_dying       )(paddr_t gpa);
     void          (*trace_emul_write_val  )(const void *ptr, unsigned long vaddr,
                                             const void *src, unsigned int bytes);