[Xen-devel] [v7][RFC][PATCH 08/13] xen/x86/p2m: set p2m_access_n for reserved device memory mapping

[Tiejun Chen <tiejun.chen@xxxxxxxxx>]

In case of shared-ept or non-shared-ept but 1:1 mapping, we
need to set p2m_access_n to make sure all reserved device
memory can't be accessed by any !iommu approach.

Signed-off-by: Tiejun Chen <tiejun.chen@xxxxxxxxx>
---
 xen/arch/x86/mm/p2m.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index efa49dd..97eb6fd 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -686,6 +686,30 @@ guest_physmap_add_entry(struct domain *d, unsigned long 
gfn,
     /* Now, actually do the two-way mapping */
     if ( mfn_valid(_mfn(mfn)) ) 
     {
+
+        if ( !is_hardware_domain(d) )
+        {
+            rc = 
iommu_get_reserved_device_memory(p2m_check_reserved_device_memory,
+                                                  &gfn);
+            if ( rc )
+            {
+                /*
+                 * Just set p2m_access_n in case of shared-ept
+                 * or non-shared ept but 1:1 mapping.
+                 */
+                if ( iommu_use_hap_pt(d) ||
+                     (!iommu_use_hap_pt(d) && mfn == gfn) )
+                {
+                    rc = p2m_set_entry(p2m, gfn, _mfn(mfn), page_order, t,
+                                       p2m_access_n);
+                    if ( rc )
+                        gdprintk(XENLOG_WARNING, "set rdm p2m failed: 
(%#lx)\n",
+                                 gfn);
+                    goto out; /* Failed to update rdm p2m. */
+                }
+            }
+        }
+
         rc = p2m_set_entry(p2m, gfn, _mfn(mfn), page_order, t,
                            p2m->default_access);
         if ( rc )
-- 
1.9.1


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