[Xen-changelog] Shadow mode's writable-PTs should only allow guest kernels access to PTs

[Xen patchbot -unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User maf46@xxxxxxxxxxxxxxxxx
# Node ID 390e4d63cdb1de2a86c60cecdc4f82c5d69f3aca
# Parent  43564304cf9448ad8978df6d2d0d6721b4615143

Shadow mode's writable-PTs should only allow guest kernels access to PTs

diff -r 43564304cf94 -r 390e4d63cdb1 xen/arch/x86/shadow32.c
--- a/xen/arch/x86/shadow32.c   Mon Jul 18 20:22:11 2005
+++ b/xen/arch/x86/shadow32.c   Tue Jul 19 10:40:26 2005
@@ -2612,7 +2612,7 @@
 
         if ( unlikely(!(l1e_get_flags(gpte) & _PAGE_RW)) )
         {
-            if ( shadow_mode_page_writable(d, l1e_get_pfn(gpte)) )
+            if ( shadow_mode_page_writable(va, regs, l1e_get_pfn(gpte)) )
             {
                 allow_writes = 1;
                 l1e_add_flags(gpte, _PAGE_RW);
diff -r 43564304cf94 -r 390e4d63cdb1 xen/arch/x86/shadow.c
--- a/xen/arch/x86/shadow.c     Mon Jul 18 20:22:11 2005
+++ b/xen/arch/x86/shadow.c     Tue Jul 19 10:40:26 2005
@@ -1684,7 +1684,7 @@
 
         if ( unlikely(!(l1e_get_flags(gpte) & _PAGE_RW)) )
         {
-            if ( shadow_mode_page_writable(d, l1e_get_pfn(gpte)) )
+            if ( shadow_mode_page_writable(va, regs, l1e_get_pfn(gpte)) )
             {
                 allow_writes = 1;
                 l1e_add_flags(gpte, _PAGE_RW);
diff -r 43564304cf94 -r 390e4d63cdb1 xen/include/asm-x86/shadow.h
--- a/xen/include/asm-x86/shadow.h      Mon Jul 18 20:22:11 2005
+++ b/xen/include/asm-x86/shadow.h      Tue Jul 19 10:40:26 2005
@@ -1691,8 +1691,10 @@
 /************************************************************************/
 
 static inline int
-shadow_mode_page_writable(struct domain *d, unsigned long gpfn)
-{
+shadow_mode_page_writable(unsigned long va, struct cpu_user_regs *regs, 
unsigned long gpfn)
+{
+    struct vcpu *v = current;
+    struct domain *d = v->domain;
     unsigned long mfn = __gpfn_to_mfn(d, gpfn);
     u32 type = frame_table[mfn].u.inuse.type_info & PGT_type_mask;
 
@@ -1701,11 +1703,14 @@
         type = shadow_max_pgtable_type(d, gpfn, NULL);
 
     if ( VM_ASSIST(d, VMASST_TYPE_writable_pagetables) &&
-         (type == PGT_l1_page_table) )
+         (type == PGT_l1_page_table) &&
+         (va < HYPERVISOR_VIRT_START) &&
+         KERNEL_MODE(v, regs) )
         return 1;
 
     if ( shadow_mode_write_all(d) &&
-         type && (type <= PGT_l4_page_table) )
+         type && (type <= PGT_l4_page_table) &&
+         KERNEL_MODE(v, regs) )
         return 1;
 
     return 0;

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