[PATCH 06/16] x86/shadow: purge {write,cmpxchg}_guest_entry() hooks

[Jan Beulich <jbeulich@xxxxxxxx>]

These aren't mode dependent (see 06f04f54ba97 ["x86/shadow:
sh_{write,cmpxchg}_guest_entry() are PV-only"], where they were moved
out of multi.c) and hence there's no need to have pointers to the
functions in struct shadow_paging_mode. Due to include dependencies,
however, the "paging" wrappers need to move out of paging.h; they're
needed from PV memory management code only anyway, so by moving them
their exposure is reduced at the same time.

By carefully placing the (moved and renamed) shadow function
declarations, #ifdef can also be dropped from the "paging" wrappers
(paging_mode_shadow() is constant false when !SHADOW_PAGING).

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/xen/arch/x86/include/asm/paging.h
+++ b/xen/arch/x86/include/asm/paging.h
@@ -98,13 +98,6 @@
 
 struct shadow_paging_mode {
 #ifdef CONFIG_SHADOW_PAGING
-#ifdef CONFIG_PV
-    void          (*write_guest_entry     )(struct vcpu *v, intpte_t *p,
-                                            intpte_t new, mfn_t gmfn);
-    intpte_t      (*cmpxchg_guest_entry   )(struct vcpu *v, intpte_t *p,
-                                            intpte_t old, intpte_t new,
-                                            mfn_t gmfn);
-#endif
 #ifdef CONFIG_HVM
     int           (*guess_wrmap           )(struct vcpu *v, 
                                             unsigned long vaddr, mfn_t gmfn);
@@ -326,44 +319,6 @@ static inline void paging_update_paging_
     v->domain->arch.paging.update_paging_modes(v);
 }
 
-#ifdef CONFIG_PV
-
-/*
- * Write a new value into the guest pagetable, and update the
- * paging-assistance state appropriately.  Returns false if we page-faulted,
- * true for success.
- */
-static inline void paging_write_guest_entry(
-    struct vcpu *v, intpte_t *p, intpte_t new, mfn_t gmfn)
-{
-#ifdef CONFIG_SHADOW_PAGING
-    if ( unlikely(paging_mode_shadow(v->domain)) && paging_get_hostmode(v) )
-        paging_get_hostmode(v)->shadow.write_guest_entry(v, p, new, gmfn);
-    else
-#endif
-        write_atomic(p, new);
-}
-
-
-/*
- * Cmpxchg a new value into the guest pagetable, and update the
- * paging-assistance state appropriately.  Returns false if we page-faulted,
- * true if not.  N.B. caller should check the value of "old" to see if the
- * cmpxchg itself was successful.
- */
-static inline intpte_t paging_cmpxchg_guest_entry(
-    struct vcpu *v, intpte_t *p, intpte_t old, intpte_t new, mfn_t gmfn)
-{
-#ifdef CONFIG_SHADOW_PAGING
-    if ( unlikely(paging_mode_shadow(v->domain)) && paging_get_hostmode(v) )
-        return paging_get_hostmode(v)->shadow.cmpxchg_guest_entry(v, p, old,
-                                                                  new, gmfn);
-#endif
-    return cmpxchg(p, old, new);
-}
-
-#endif /* CONFIG_PV */
-
 /* Helper function that writes a pte in such a way that a concurrent read 
  * never sees a half-written entry that has _PAGE_PRESENT set */
 static inline void safe_write_pte(l1_pgentry_t *p, l1_pgentry_t new)
--- a/xen/arch/x86/include/asm/shadow.h
+++ b/xen/arch/x86/include/asm/shadow.h
@@ -248,6 +248,12 @@ static inline void pv_l1tf_domain_destro
 #endif
 }
 
+/* Functions that atomically write PV guest PT entries */
+void shadow_write_guest_entry(
+    struct vcpu *v, intpte_t *p, intpte_t new, mfn_t gmfn);
+intpte_t shadow_cmpxchg_guest_entry(
+    struct vcpu *v, intpte_t *p, intpte_t old, intpte_t new, mfn_t gmfn);
+
 #endif /* CONFIG_PV */
 
 /* Remove all shadows of the guest mfn. */
--- a/xen/arch/x86/mm/shadow/multi.c
+++ b/xen/arch/x86/mm/shadow/multi.c
@@ -4131,10 +4131,6 @@ const struct paging_mode sh_paging_mode
 #endif
     .update_cr3                    = sh_update_cr3,
     .guest_levels                  = GUEST_PAGING_LEVELS,
-#ifdef CONFIG_PV
-    .shadow.write_guest_entry      = sh_write_guest_entry,
-    .shadow.cmpxchg_guest_entry    = sh_cmpxchg_guest_entry,
-#endif
 #ifdef CONFIG_HVM
 #if SHADOW_OPTIMIZATIONS & SHOPT_WRITABLE_HEURISTIC
     .shadow.guess_wrmap            = sh_guess_wrmap,
--- a/xen/arch/x86/mm/shadow/private.h
+++ b/xen/arch/x86/mm/shadow/private.h
@@ -428,12 +428,6 @@ static inline int sh_remove_write_access
 }
 #endif
 
-/* Functions that atomically write PV guest PT entries */
-void cf_check sh_write_guest_entry(
-    struct vcpu *v, intpte_t *p, intpte_t new, mfn_t gmfn);
-intpte_t cf_check sh_cmpxchg_guest_entry(
-    struct vcpu *v, intpte_t *p, intpte_t old, intpte_t new, mfn_t gmfn);
-
 /* Unhook the non-Xen mappings in this top-level shadow mfn.
  * With user_only == 1, unhooks only the user-mode mappings. */
 void shadow_unhook_mappings(struct domain *d, mfn_t smfn, int user_only);
--- a/xen/arch/x86/mm/shadow/pv.c
+++ b/xen/arch/x86/mm/shadow/pv.c
@@ -28,8 +28,8 @@
  * Write a new value into the guest pagetable, and update the shadows
  * appropriately.
  */
-void cf_check
-sh_write_guest_entry(struct vcpu *v, intpte_t *p, intpte_t new, mfn_t gmfn)
+void
+shadow_write_guest_entry(struct vcpu *v, intpte_t *p, intpte_t new, mfn_t gmfn)
 {
     paging_lock(v->domain);
     write_atomic(p, new);
@@ -42,9 +42,9 @@ sh_write_guest_entry(struct vcpu *v, int
  * appropriately.  Returns the previous entry found, which the caller is
  * expected to check to see if the cmpxchg was successful.
  */
-intpte_t cf_check
-sh_cmpxchg_guest_entry(struct vcpu *v, intpte_t *p, intpte_t old,
-                       intpte_t new, mfn_t gmfn)
+intpte_t
+shadow_cmpxchg_guest_entry(struct vcpu *v, intpte_t *p, intpte_t old,
+                           intpte_t new, mfn_t gmfn)
 {
     intpte_t t;
 
--- a/xen/arch/x86/pv/mm.h
+++ b/xen/arch/x86/pv/mm.h
@@ -1,6 +1,8 @@
 #ifndef __PV_MM_H__
 #define __PV_MM_H__
 
+#include <asm/shadow.h>
+
 l1_pgentry_t *map_guest_l1e(unsigned long linear, mfn_t *gl1mfn);
 
 int new_guest_cr3(mfn_t mfn);
@@ -32,6 +34,35 @@ static inline l1_pgentry_t guest_get_eff
 }
 
 /*
+ * Write a new value into the guest pagetable, and update the
+ * paging-assistance state appropriately.  Returns false if we page-faulted,
+ * true for success.
+ */
+static inline void paging_write_guest_entry(
+    struct vcpu *v, intpte_t *p, intpte_t new, mfn_t gmfn)
+{
+    if ( unlikely(paging_mode_shadow(v->domain)) )
+        shadow_write_guest_entry(v, p, new, gmfn);
+    else
+        write_atomic(p, new);
+}
+
+
+/*
+ * Cmpxchg a new value into the guest pagetable, and update the
+ * paging-assistance state appropriately.  Returns false if we page-faulted,
+ * true if not.  N.B. caller should check the value of "old" to see if the
+ * cmpxchg itself was successful.
+ */
+static inline intpte_t paging_cmpxchg_guest_entry(
+    struct vcpu *v, intpte_t *p, intpte_t old, intpte_t new, mfn_t gmfn)
+{
+    if ( unlikely(paging_mode_shadow(v->domain)) )
+        return shadow_cmpxchg_guest_entry(v, p, old, new, gmfn);
+    return cmpxchg(p, old, new);
+}
+
+/*
  * PTE updates can be done with ordinary writes except:
  *  1. Debug builds get extra checking by using CMPXCHG[8B].
  */