[Xen-devel] [PATCH 02/11] VMX: implement suppress #VE.

[Ed White <edmund.h.white@xxxxxxxxx>]

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

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@xxxxxxxxx>
---
 xen/arch/x86/mm/p2m-ept.c         | 34 +++++++++++++++++++++++++++++++++-
 xen/include/asm-x86/hvm/vmx/vmx.h |  1 +
 2 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/xen/arch/x86/mm/p2m-ept.c b/xen/arch/x86/mm/p2m-ept.c
index eb8b5f9..2b9f07c 100644
--- a/xen/arch/x86/mm/p2m-ept.c
+++ b/xen/arch/x86/mm/p2m-ept.c
@@ -41,7 +41,7 @@
 #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);
+    return (e->valid != 0 && e->sa_p2mt != p2m_invalid);
 }
 
 /* returns : 0 for success, -errno otherwise */
@@ -194,6 +194,19 @@ static int ept_set_middle_entry(struct p2m_domain *p2m, 
ept_entry_t *ept_entry)
 
     ept_entry->r = ept_entry->w = ept_entry->x = 1;
 
+    /* Disable #VE on all entries */ 
+    if ( cpu_has_vmx_virt_exceptions )
+    {
+        ept_entry_t *table = __map_domain_page(pg);
+
+        for ( int i = 0; i < EPT_PAGETABLE_ENTRIES; i++ )
+            table[i].suppress_ve = 1;
+
+        unmap_domain_page(table);
+
+        ept_entry->suppress_ve = 1;
+    }
+
     return 1;
 }
 
@@ -243,6 +256,10 @@ 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);
+
+        if ( cpu_has_vmx_virt_exceptions )
+            epte->suppress_ve = 1;
+
         ASSERT(!epte->rsvd1);
 
         ept_p2m_type_to_flags(epte, epte->sa_p2mt, epte->access);
@@ -753,6 +770,9 @@ ept_set_entry(struct p2m_domain *p2m, unsigned long gfn, 
mfn_t mfn,
         ept_p2m_type_to_flags(&new_entry, p2mt, p2ma);
     }
 
+    if ( cpu_has_vmx_virt_exceptions )
+        new_entry.suppress_ve = 1;
+
     rc = atomic_write_ept_entry(ept_entry, new_entry, target);
     if ( unlikely(rc) )
         old_entry.epte = 0;
@@ -1069,6 +1089,18 @@ int ept_p2m_init(struct p2m_domain *p2m)
     /* set EPT page-walk length, now it's actual walk length - 1, i.e. 3 */
     ept->ept_wl = 3;
 
+    /* Disable #VE on all entries */
+    if ( cpu_has_vmx_virt_exceptions )
+    {
+        ept_entry_t *table =
+            map_domain_page(pagetable_get_pfn(p2m_get_pagetable(p2m)));
+
+        for ( int i = 0; i < EPT_PAGETABLE_ENTRIES; i++ )
+            table[i].suppress_ve = 1;
+
+        unmap_domain_page(table);
+    }
+
     if ( !zalloc_cpumask_var(&ept->synced_mask) )
         return -ENOMEM;
 
diff --git a/xen/include/asm-x86/hvm/vmx/vmx.h 
b/xen/include/asm-x86/hvm/vmx/vmx.h
index 8bae195..70fee74 100644
--- a/xen/include/asm-x86/hvm/vmx/vmx.h
+++ b/xen/include/asm-x86/hvm/vmx/vmx.h
@@ -49,6 +49,7 @@ typedef union {
         suppress_ve :   1;  /* bit 63 - suppress #VE */
     };
     u64 epte;
+    u64 valid       :   63; /* entire EPTE except suppress #VE bit */
 } ept_entry_t;
 
 typedef struct {
-- 
1.9.1


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