[PATCH v2 1/5] x86/paging: fold most HAP and shadow final teardown

[Jan Beulich <jbeulich@xxxxxxxx>]

HAP does a few things beyond what's common, which are left there at
least for now. Common operations, however, are moved to
paging_final_teardown(), allowing shadow_final_teardown() to go away.

While moving (and hence generalizing) the respective SHADOW_PRINTK()
drop the logging of total_pages from the 2nd instance - the value is
necessarily zero after {hap,shadow}_set_allocation() - and shorten the
messages, in part accounting for PAGING_PRINTK() logging __func__
already.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
The remaining parts of hap_final_teardown() could be moved as well, at
the price of a CONFIG_HVM conditional. I wasn't sure whether that was
deemed reasonable.
---
v2: Shorten PAGING_PRINTK() messages. Adjust comments while being
    moved.

--- a/xen/arch/x86/include/asm/shadow.h
+++ b/xen/arch/x86/include/asm/shadow.h
@@ -78,9 +78,6 @@ int shadow_domctl(struct domain *d,
 void shadow_vcpu_teardown(struct vcpu *v);
 void shadow_teardown(struct domain *d, bool *preempted);
 
-/* Call once all of the references to the domain have gone away */
-void shadow_final_teardown(struct domain *d);
-
 void sh_remove_shadows(struct domain *d, mfn_t gmfn, int fast, int all);
 
 /* Adjust shadows ready for a guest page to change its type. */
--- a/xen/arch/x86/mm/hap/hap.c
+++ b/xen/arch/x86/mm/hap/hap.c
@@ -268,8 +268,8 @@ static void hap_free(struct domain *d, m
 
     /*
      * For dying domains, actually free the memory here. This way less work is
-     * left to hap_final_teardown(), which cannot easily have preemption checks
-     * added.
+     * left to paging_final_teardown(), which cannot easily have preemption
+     * checks added.
      */
     if ( unlikely(d->is_dying) )
     {
@@ -552,18 +552,6 @@ void hap_final_teardown(struct domain *d
     for (i = 0; i < MAX_NESTEDP2M; i++) {
         p2m_teardown(d->arch.nested_p2m[i], true, NULL);
     }
-
-    if ( d->arch.paging.total_pages != 0 )
-        hap_teardown(d, NULL);
-
-    p2m_teardown(p2m_get_hostp2m(d), true, NULL);
-    /* Free any memory that the p2m teardown released */
-    paging_lock(d);
-    hap_set_allocation(d, 0, NULL);
-    ASSERT(d->arch.paging.p2m_pages == 0);
-    ASSERT(d->arch.paging.free_pages == 0);
-    ASSERT(d->arch.paging.total_pages == 0);
-    paging_unlock(d);
 }
 
 void hap_vcpu_teardown(struct vcpu *v)
--- a/xen/arch/x86/mm/paging.c
+++ b/xen/arch/x86/mm/paging.c
@@ -842,10 +842,45 @@ int paging_teardown(struct domain *d)
 /* Call once all of the references to the domain have gone away */
 void paging_final_teardown(struct domain *d)
 {
-    if ( hap_enabled(d) )
+    bool hap = hap_enabled(d);
+
+    PAGING_PRINTK("%pd start: total = %u, free = %u, p2m = %u\n",
+                  d, d->arch.paging.total_pages,
+                  d->arch.paging.free_pages, d->arch.paging.p2m_pages);
+
+    if ( hap )
         hap_final_teardown(d);
+
+    /*
+     * Remove remaining paging memory.  This can be nonzero on certain error
+     * paths.
+     */
+    if ( d->arch.paging.total_pages )
+    {
+        if ( hap )
+            hap_teardown(d, NULL);
+        else
+            shadow_teardown(d, NULL);
+    }
+
+    /* It is now safe to pull down the p2m map. */
+    p2m_teardown(p2m_get_hostp2m(d), true, NULL);
+
+    /* Free any paging memory that the p2m teardown released. */
+    paging_lock(d);
+
+    if ( hap )
+        hap_set_allocation(d, 0, NULL);
     else
-        shadow_final_teardown(d);
+        shadow_set_allocation(d, 0, NULL);
+
+    PAGING_PRINTK("%pd done: free = %u, p2m = %u\n",
+                  d, d->arch.paging.free_pages, d->arch.paging.p2m_pages);
+    ASSERT(!d->arch.paging.p2m_pages);
+    ASSERT(!d->arch.paging.free_pages);
+    ASSERT(!d->arch.paging.total_pages);
+
+    paging_unlock(d);
 
     p2m_final_teardown(d);
 }
--- a/xen/arch/x86/mm/shadow/common.c
+++ b/xen/arch/x86/mm/shadow/common.c
@@ -1194,7 +1194,7 @@ void shadow_free(struct domain *d, mfn_t
 
         /*
          * For dying domains, actually free the memory here. This way less
-         * work is left to shadow_final_teardown(), which cannot easily have
+         * work is left to paging_final_teardown(), which cannot easily have
          * preemption checks added.
          */
         if ( unlikely(dying) )
@@ -2898,35 +2898,6 @@ out:
     }
 }
 
-void shadow_final_teardown(struct domain *d)
-/* Called by arch_domain_destroy(), when it's safe to pull down the p2m map. */
-{
-    SHADOW_PRINTK("dom %u final teardown starts."
-                   "  Shadow pages total = %u, free = %u, p2m=%u\n",
-                   d->domain_id, d->arch.paging.total_pages,
-                   d->arch.paging.free_pages, d->arch.paging.p2m_pages);
-
-    /* Double-check that the domain didn't have any shadow memory.
-     * It is possible for a domain that never got domain_kill()ed
-     * to get here with its shadow allocation intact. */
-    if ( d->arch.paging.total_pages != 0 )
-        shadow_teardown(d, NULL);
-
-    /* It is now safe to pull down the p2m map. */
-    p2m_teardown(p2m_get_hostp2m(d), true, NULL);
-    /* Free any shadow memory that the p2m teardown released */
-    paging_lock(d);
-    shadow_set_allocation(d, 0, NULL);
-    SHADOW_PRINTK("dom %u final teardown done."
-                   "  Shadow pages total = %u, free = %u, p2m=%u\n",
-                   d->domain_id, d->arch.paging.total_pages,
-                   d->arch.paging.free_pages, d->arch.paging.p2m_pages);
-    ASSERT(d->arch.paging.p2m_pages == 0);
-    ASSERT(d->arch.paging.free_pages == 0);
-    ASSERT(d->arch.paging.total_pages == 0);
-    paging_unlock(d);
-}
-
 static int shadow_one_bit_enable(struct domain *d, u32 mode)
 /* Turn on a single shadow mode feature */
 {