1 files changed, 70 insertions, 0 deletions
diff --git a/xsa286-1.patch b/xsa286-1.patch
new file mode 100644
index 0000000..f0f51d5
--- /dev/null
+++ b/xsa286-1.patch
@@ -0,0 +1,70 @@
+x86/mm: split L4 and L3 parts of the walk out of do_page_walk()
+
+The L3 one at least is going to be re-used by a subsequent patch, and
+splitting the L4 one then as well seems only natural.
+
+This is part of XSA-286.
+
+Signed-off-by: Jan Beulich <jbeulich@suse.com>
+Reviewed-by: George Dunlap <george.dunlap@citrix.com>
+Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
+
+--- a/xen/arch/x86/x86_64/mm.c
++++ b/xen/arch/x86/x86_64/mm.c
+@@ -44,26 +44,47 @@ unsigned int __read_mostly m2p_compat_vs
+ 
+ l2_pgentry_t *compat_idle_pg_table_l2;
+ 
+-void *do_page_walk(struct vcpu *v, unsigned long addr)
++static l4_pgentry_t page_walk_get_l4e(pagetable_t root, unsigned long addr)
+ {
+-    unsigned long mfn = pagetable_get_pfn(v->arch.guest_table);
+-    l4_pgentry_t l4e, *l4t;
+-    l3_pgentry_t l3e, *l3t;
+-    l2_pgentry_t l2e, *l2t;
+-    l1_pgentry_t l1e, *l1t;
++    unsigned long mfn = pagetable_get_pfn(root);
++    l4_pgentry_t *l4t, l4e;
+ 
+-    if ( !is_pv_vcpu(v) || !is_canonical_address(addr) )
+-        return NULL;
++    if ( !is_canonical_address(addr) )
++        return l4e_empty();
+ 
+     l4t = map_domain_page(_mfn(mfn));
+     l4e = l4t[l4_table_offset(addr)];
+     unmap_domain_page(l4t);
++
++    return l4e;
++}
++
++static l3_pgentry_t page_walk_get_l3e(pagetable_t root, unsigned long addr)
++{
++    l4_pgentry_t l4e = page_walk_get_l4e(root, addr);
++    l3_pgentry_t *l3t, l3e;
++
+     if ( !(l4e_get_flags(l4e) & _PAGE_PRESENT) )
+-        return NULL;
++        return l3e_empty();
+ 
+     l3t = map_l3t_from_l4e(l4e);
+     l3e = l3t[l3_table_offset(addr)];
+     unmap_domain_page(l3t);
++
++    return l3e;
++}
++
++void *do_page_walk(struct vcpu *v, unsigned long addr)
++{
++    l3_pgentry_t l3e;
++    l2_pgentry_t l2e, *l2t;
++    l1_pgentry_t l1e, *l1t;
++    unsigned long mfn;
++
++    if ( !is_pv_vcpu(v) )
++        return NULL;
++
++    l3e = page_walk_get_l3e(v->arch.guest_table, addr);
+     mfn = l3e_get_pfn(l3e);
+     if ( !(l3e_get_flags(l3e) & _PAGE_PRESENT) || !mfn_valid(_mfn(mfn)) )
+         return NULL;