[Xen-devel] [PATCH v1 for-4.6 1/2] xen/pvh: check permissions when adding MMIO regions

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

Check that MMIO regions added to PVH Dom0 are allowed. Previously a PVH Dom0
would have access to the full MMIO range.

Signed-off-by: Roger Pau Monnà <roger.pau@xxxxxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 xen/arch/x86/domain_build.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/xen/arch/x86/domain_build.c b/xen/arch/x86/domain_build.c
index 7a6afea..aa3bf0f 100644
--- a/xen/arch/x86/domain_build.c
+++ b/xen/arch/x86/domain_build.c
@@ -312,16 +312,47 @@ static __init void pvh_add_mem_mapping(struct domain *d, 
unsigned long gfn,
                                        unsigned long mfn, unsigned long 
nr_mfns)
 {
     unsigned long i;
+    xenmem_access_t def_access;
+    bool_t r_only = false;
     int rc;
 
     for ( i = 0; i < nr_mfns; i++ )
     {
+        if ( !iomem_access_permitted(d, mfn + i, mfn + i) )
+            goto next;
+
+        if ( rangeset_contains_singleton(mmio_ro_ranges, mfn + i) && !r_only )
+        {
+            rc = p2m_get_mem_access(d, ~0ul, &def_access);
+            BUG_ON(rc);
+            /* Set default access to read-only */
+            rc = p2m_set_mem_access(d, ~0ul, 0, 0, 0, XENMEM_access_r);
+            BUG_ON(rc);
+            r_only = true;
+        }
+        else if ( r_only )
+        {
+            /* Set the default back */
+            rc = p2m_set_mem_access(d, ~0ul, 0, 0, 0, def_access);
+            BUG_ON(rc);
+            r_only = false;
+        }
+
         if ( (rc = set_mmio_p2m_entry(d, gfn + i, _mfn(mfn + i))) )
             panic("pvh_add_mem_mapping: gfn:%lx mfn:%lx i:%ld rc:%d\n",
                   gfn, mfn, i, rc);
+
+ next:
         if ( !(i & 0xfffff) )
                 process_pending_softirqs();
     }
+
+    if ( r_only )
+    {
+        /* Set the default back */
+        rc = p2m_set_mem_access(d, ~0ul, 0, 0, 0, def_access);
+        BUG_ON(rc);
+    }
 }
 
 /*
-- 
1.9.3 (Apple Git-50)


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