[PATCH v3 04/12] x86/shadow: use lighter weight mode checks

[Jan Beulich <jbeulich@xxxxxxxx>]

shadow_mode_...(), with the exception of shadow_mode_enabled(), are
shorthands for shadow_mode_enabled() && paging_mode_...(). While
potentially useful outside of shadow-internal functions, when we already
know that we're dealing with a domain in shadow mode, the "paging"
checks are sufficient and cheaper. While the "shadow" ones commonly
translate to a MOV/AND/CMP/Jcc sequence, the "paging" ones typically
resolve to just TEST+Jcc.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
v2: Re-base over new earlier patch.

--- a/xen/arch/x86/mm/shadow/common.c
+++ b/xen/arch/x86/mm/shadow/common.c
@@ -1843,7 +1843,7 @@ int sh_remove_write_access(struct domain
      * In guest refcounting, we trust Xen to already be restricting
      * all the writes to the guest page tables, so we do not need to
      * do more. */
-    if ( !shadow_mode_refcounts(d) )
+    if ( !paging_mode_refcounts(d) )
         return 0;
 
     /* Early exit if it's already a pagetable, or otherwise not writeable */
@@ -2075,7 +2075,7 @@ int sh_remove_all_mappings(struct domain
          *   guest pages with an extra reference taken by
          *   prepare_ring_for_helper().
          */
-        if ( !(shadow_mode_external(d)
+        if ( !(paging_mode_external(d)
                && (page->count_info & PGC_count_mask) <= 3
                && ((page->u.inuse.type_info & PGT_count_mask)
                    == (is_special_page(page) ||
@@ -2372,8 +2372,8 @@ static void sh_update_paging_modes(struc
     {
         const struct paging_mode *old_mode = v->arch.paging.mode;
 
-        ASSERT(shadow_mode_translate(d));
-        ASSERT(shadow_mode_external(d));
+        ASSERT(paging_mode_translate(d));
+        ASSERT(paging_mode_external(d));
 
 #if (SHADOW_OPTIMIZATIONS & SHOPT_OUT_OF_SYNC)
         /* Need to resync all our pages now, because if a page goes out
@@ -2760,7 +2760,7 @@ void shadow_vcpu_teardown(struct vcpu *v
 
     sh_detach_old_tables(v);
 #ifdef CONFIG_HVM
-    if ( shadow_mode_external(d) )
+    if ( paging_mode_external(d) )
     {
         mfn_t mfn = pagetable_get_mfn(v->arch.hvm.monitor_table);
 
--- a/xen/arch/x86/mm/shadow/multi.c
+++ b/xen/arch/x86/mm/shadow/multi.c
@@ -514,7 +514,7 @@ _sh_propagate(struct vcpu *v,
                || (level == 1
                    && page_get_owner(mfn_to_page(target_mfn)) == dom_io);
     if ( mmio_mfn
-         && !(level == 1 && (!shadow_mode_refcounts(d)
+         && !(level == 1 && (!paging_mode_refcounts(d)
                              || p2mt == p2m_mmio_direct)) )
     {
         ASSERT((ft == ft_prefetch));
@@ -531,7 +531,7 @@ _sh_propagate(struct vcpu *v,
                        _PAGE_RW | _PAGE_PRESENT);
     if ( guest_nx_enabled(v) )
         pass_thru_flags |= _PAGE_NX_BIT;
-    if ( level == 1 && !shadow_mode_refcounts(d) && mmio_mfn )
+    if ( level == 1 && !paging_mode_refcounts(d) && mmio_mfn )
         pass_thru_flags |= PAGE_CACHE_ATTRS;
     sflags = gflags & pass_thru_flags;
 
@@ -651,7 +651,7 @@ _sh_propagate(struct vcpu *v,
      * (We handle log-dirty entirely inside the shadow code, without using the
      * p2m_ram_logdirty p2m type: only HAP uses that.)
      */
-    if ( level == 1 && unlikely(shadow_mode_log_dirty(d)) && !mmio_mfn )
+    if ( level == 1 && unlikely(paging_mode_log_dirty(d)) && !mmio_mfn )
     {
         if ( ft & FETCH_TYPE_WRITE )
             paging_mark_dirty(d, target_mfn);
@@ -807,7 +807,7 @@ do {
 #define FOREACH_PRESENT_L2E(_sl2mfn, _sl2e, _gl2p, _done, _dom, _code)    \
 do {                                                                      \
     int _i, _j;                                                           \
-    ASSERT(shadow_mode_external(_dom));                                   \
+    ASSERT(paging_mode_external(_dom));                                   \
     ASSERT(mfn_to_page(_sl2mfn)->u.sh.type == SH_type_l2_32_shadow);      \
     for ( _j = 0; _j < 4; _j++ )                                          \
     {                                                                     \
@@ -833,7 +833,7 @@ do {
 do {                                                                       \
     int _i;                                                                \
     shadow_l2e_t *_sp = map_domain_page((_sl2mfn));                        \
-    ASSERT(shadow_mode_external(_dom));                                    \
+    ASSERT(paging_mode_external(_dom));                                    \
     ASSERT(mfn_to_page(_sl2mfn)->u.sh.type == SH_type_l2_pae_shadow);      \
     for ( _i = 0; _i < SHADOW_L2_PAGETABLE_ENTRIES; _i++ )                 \
     {                                                                      \
@@ -854,7 +854,7 @@ do {
     unsigned int _i, _end = SHADOW_L2_PAGETABLE_ENTRIES;                    \
     shadow_l2e_t *_sp = map_domain_page((_sl2mfn));                         \
     ASSERT_VALID_L2(mfn_to_page(_sl2mfn)->u.sh.type);                       \
-    if ( is_pv_32bit_domain(_dom) /* implies !shadow_mode_external */ &&    \
+    if ( is_pv_32bit_domain(_dom) /* implies !paging_mode_external */ &&    \
          mfn_to_page(_sl2mfn)->u.sh.type != SH_type_l2_64_shadow )          \
         _end = COMPAT_L2_PAGETABLE_FIRST_XEN_SLOT(_dom);                    \
     for ( _i = 0; _i < _end; ++_i )                                         \
@@ -896,7 +896,7 @@ do {
 #define FOREACH_PRESENT_L4E(_sl4mfn, _sl4e, _gl4p, _done, _dom, _code)  \
 do {                                                                    \
     shadow_l4e_t *_sp = map_domain_page((_sl4mfn));                     \
-    int _xen = !shadow_mode_external(_dom);                             \
+    int _xen = !paging_mode_external(_dom);                             \
     int _i;                                                             \
     ASSERT(mfn_to_page(_sl4mfn)->u.sh.type == SH_type_l4_64_shadow);\
     for ( _i = 0; _i < SHADOW_L4_PAGETABLE_ENTRIES; _i++ )              \
@@ -965,7 +965,7 @@ sh_make_shadow(struct vcpu *v, mfn_t gmf
 #endif
 
     // Create the Xen mappings...
-    if ( !shadow_mode_external(d) )
+    if ( !paging_mode_external(d) )
     {
         switch (shadow_type)
         {
@@ -1367,7 +1367,7 @@ void sh_destroy_l1_shadow(struct domain
         shadow_demote(d, gmfn, t);
     }
 
-    if ( shadow_mode_refcounts(d) )
+    if ( paging_mode_refcounts(d) )
     {
         /* Decrement refcounts of all the old entries */
         mfn_t sl1mfn = smfn;
@@ -1464,7 +1464,7 @@ static int cf_check validate_gl4e(
     l4e_propagate_from_guest(v, new_gl4e, sl3mfn, &new_sl4e, ft_prefetch);
 
     // check for updates to xen reserved slots
-    if ( !shadow_mode_external(d) )
+    if ( !paging_mode_external(d) )
     {
         int shadow_index = (((unsigned long)sl4p & ~PAGE_MASK) /
                             sizeof(shadow_l4e_t));
@@ -2387,7 +2387,7 @@ static int cf_check sh_page_fault(
     gfn = guest_walk_to_gfn(&gw);
     gmfn = get_gfn(d, gfn, &p2mt);
 
-    if ( shadow_mode_refcounts(d) &&
+    if ( paging_mode_refcounts(d) &&
          ((!p2m_is_valid(p2mt) && !p2m_is_grant(p2mt)) ||
           (!p2m_is_mmio(p2mt) && !mfn_valid(gmfn))) )
     {
@@ -2611,7 +2611,7 @@ static int cf_check sh_page_fault(
     return EXCRET_fault_fixed;
 
  emulate:
-    if ( !shadow_mode_refcounts(d) )
+    if ( !paging_mode_refcounts(d) )
         goto not_a_shadow_fault;
 
 #ifdef CONFIG_HVM
@@ -3055,7 +3055,7 @@ sh_update_linear_entries(struct vcpu *v)
      */
 
     /* Don't try to update the monitor table if it doesn't exist */
-    if ( !shadow_mode_external(d) ||
+    if ( !paging_mode_external(d) ||
          pagetable_get_pfn(v->arch.hvm.monitor_table) == 0 )
         return;
 
@@ -3204,7 +3204,7 @@ static void cf_check sh_update_cr3(struc
     /* Double-check that the HVM code has sent us a sane guest_table */
     if ( is_hvm_domain(d) )
     {
-        ASSERT(shadow_mode_external(d));
+        ASSERT(paging_mode_external(d));
         if ( hvm_paging_enabled(v) )
             ASSERT(pagetable_get_pfn(v->arch.guest_table));
         else
@@ -3229,7 +3229,7 @@ static void cf_check sh_update_cr3(struc
      * table.  We cache the current state of that table and shadow that,
      * until the next CR3 write makes us refresh our cache.
      */
-    ASSERT(shadow_mode_external(d));
+    ASSERT(paging_mode_external(d));
 
     /*
      * Find where in the page the l3 table is, but ignore the low 2 bits of
@@ -3260,7 +3260,7 @@ static void cf_check sh_update_cr3(struc
         ASSERT(d->is_dying || d->is_shutting_down);
         return;
     }
-    if ( !shadow_mode_external(d) && !is_pv_32bit_domain(d) )
+    if ( !paging_mode_external(d) && !is_pv_32bit_domain(d) )
     {
         mfn_t smfn = pagetable_get_mfn(v->arch.paging.shadow.shadow_table[0]);
 
@@ -3354,7 +3354,7 @@ static void cf_check sh_update_cr3(struc
     ///
     /// v->arch.cr3
     ///
-    if ( shadow_mode_external(d) )
+    if ( paging_mode_external(d) )
     {
         make_cr3(v, pagetable_get_mfn(v->arch.hvm.monitor_table));
     }
@@ -3371,7 +3371,7 @@ static void cf_check sh_update_cr3(struc
     ///
     /// v->arch.hvm.hw_cr[3]
     ///
-    if ( shadow_mode_external(d) )
+    if ( paging_mode_external(d) )
     {
         ASSERT(is_hvm_domain(d));
 #if SHADOW_PAGING_LEVELS == 3
--- a/xen/arch/x86/mm/shadow/private.h
+++ b/xen/arch/x86/mm/shadow/private.h
@@ -407,7 +407,7 @@ static inline int sh_remove_write_access
                                          unsigned int level,
                                          unsigned long fault_addr)
 {
-    ASSERT(!shadow_mode_refcounts(d));
+    ASSERT(!paging_mode_refcounts(d));
     return 0;
 }
 #endif
@@ -520,8 +520,8 @@ sh_mfn_is_a_page_table(mfn_t gmfn)
         return 0;
 
     owner = page_get_owner(page);
-    if ( owner && shadow_mode_refcounts(owner)
-         && (page->count_info & PGC_shadowed_pt) )
+    if ( owner && paging_mode_refcounts(owner) &&
+         (page->count_info & PGC_shadowed_pt) )
         return 1;
 
     type_info = page->u.inuse.type_info & PGT_type_mask;
--- a/xen/arch/x86/mm/shadow/set.c
+++ b/xen/arch/x86/mm/shadow/set.c
@@ -81,7 +81,7 @@ shadow_get_page_from_l1e(shadow_l1e_t sl
     struct domain *owner = NULL;
 
     ASSERT(!sh_l1e_is_magic(sl1e));
-    ASSERT(shadow_mode_refcounts(d));
+    ASSERT(paging_mode_refcounts(d));
 
     if ( mfn_valid(mfn) )
     {
@@ -342,7 +342,7 @@ int shadow_set_l1e(struct domain *d, sha
          !sh_l1e_is_magic(new_sl1e) )
     {
         /* About to install a new reference */
-        if ( shadow_mode_refcounts(d) )
+        if ( paging_mode_refcounts(d) )
         {
 #define PAGE_FLIPPABLE (_PAGE_RW | _PAGE_PWT | _PAGE_PCD | _PAGE_PAT)
             int rc;
@@ -375,7 +375,7 @@ int shadow_set_l1e(struct domain *d, sha
 
     old_sl1f = shadow_l1e_get_flags(old_sl1e);
     if ( (old_sl1f & _PAGE_PRESENT) && !sh_l1e_is_magic(old_sl1e) &&
-         shadow_mode_refcounts(d) )
+         paging_mode_refcounts(d) )
     {
         /*
          * We lost a reference to an old mfn.
--- a/xen/arch/x86/mm/shadow/types.h
+++ b/xen/arch/x86/mm/shadow/types.h
@@ -262,7 +262,7 @@ int shadow_set_l4e(struct domain *d, sha
 static void inline
 shadow_put_page_from_l1e(shadow_l1e_t sl1e, struct domain *d)
 {
-    if ( !shadow_mode_refcounts(d) )
+    if ( !paging_mode_refcounts(d) )
         return;
 
     put_page_from_l1e(sl1e, d);