VMX: implement suppress #VE

In preparation for selectively enabling #VE in a later patch, set
suppress #VE on all EPTE's.

Suppress #VE should always be the default condition for two reasons:
it is generally not safe to deliver #VE into a guest unless that guest
has been modified to receive it; and even then for most EPT violations only
the hypervisor is able to handle the violation.

Signed-off-by: Ed White <edmund.h.white@intel.com>
Acked-by: George Dunlap <george.dunlap@eu.citrix.com>
Acked-by: Jun Nakajima <jun.nakajima@intel.com>
Release-acked-by: Wei Liu <wei.liu2@citrix.com>

xen/arch/x86/mm/p2m-ept.c

@@ -42,7 +42,8 @@
 #define is_epte_superpage(ept_entry)    ((ept_entry)->sp)
 static inline bool_t is_epte_valid(ept_entry_t *e)
 {
-    return (e->epte != 0 && e->sa_p2mt != p2m_invalid);
+    /* suppress_ve alone is not considered valid, so mask it off */
+    return ((e->epte & ~(1ul << 63)) != 0 && e->sa_p2mt != p2m_invalid);
 }
 
 /* returns : 0 for success, -errno otherwise */
@@ -220,6 +221,8 @@ static void ept_p2m_type_to_flags(struct p2m_domain *p2m, ept_entry_t *entry,
 static int ept_set_middle_entry(struct p2m_domain *p2m, ept_entry_t *ept_entry)
 {
     struct page_info *pg;
+    ept_entry_t *table;
+    unsigned int i;
 
     pg = p2m_alloc_ptp(p2m, 0);
     if ( pg == NULL )
@@ -233,6 +236,15 @@ static int ept_set_middle_entry(struct p2m_domain *p2m, ept_entry_t *ept_entry)
     /* Manually set A bit to avoid overhead of MMU having to write it later. */
     ept_entry->a = 1;
 
+    ept_entry->suppress_ve = 1;
+
+    table = __map_domain_page(pg);
+
+    for ( i = 0; i < EPT_PAGETABLE_ENTRIES; i++ )
+        table[i].suppress_ve = 1;
+
+    unmap_domain_page(table);
+
     return 1;
 }
 
@@ -282,6 +294,7 @@ static int ept_split_super_page(struct p2m_domain *p2m, ept_entry_t *ept_entry,
         epte->sp = (level > 1);
         epte->mfn += i * trunk;
         epte->snp = (iommu_enabled && iommu_snoop);
+        epte->suppress_ve = 1;
 
         ept_p2m_type_to_flags(p2m, epte, epte->sa_p2mt, epte->access);
 
@@ -791,6 +804,8 @@ ept_set_entry(struct p2m_domain *p2m, unsigned long gfn, mfn_t mfn,
         ept_p2m_type_to_flags(p2m, &new_entry, p2mt, p2ma);
     }
 
+    new_entry.suppress_ve = 1;
+
     rc = atomic_write_ept_entry(ept_entry, new_entry, target);
     if ( unlikely(rc) )
         old_entry.epte = 0;