[Xen-devel] [v3][PATCH 03/16] xen/vtd: create RMRR mapping

[Tiejun Chen <tiejun.chen@xxxxxxxxx>]

RMRR reserved regions must be setup in the pfn space with an identity
mapping to reported mfn. However existing code has problem to setup
correct mapping when VT-d shares EPT page table, so lead to problem
when assigning devices (e.g GPU) with RMRR reported. So instead, this
patch aims to setup identity mapping in p2m layer, regardless of
whether EPT is shared or not. And we still keep creating VT-d table.

Signed-off-by: Tiejun Chen <tiejun.chen@xxxxxxxxx>
---
 xen/arch/x86/mm/p2m.c               | 10 ++++++++--
 xen/drivers/passthrough/vtd/iommu.c |  3 +--
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index a6db236..c7198a5 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -927,10 +927,16 @@ int set_identity_p2m_entry(struct domain *d, unsigned 
long gfn,
         }
 
         gfn_unlock(p2m, gfn, 0);
-        return ret;
     }
+    else
+        ret = 0;
 
-    return 0;
+    if( ret == 0 )
+    {
+        ret = iommu_map_page(d, gfn, gfn, IOMMUF_readable|IOMMUF_writable);
+    }
+
+    return ret;
 }
 
 /* Returns: 0 for success, -errno for failure */
diff --git a/xen/drivers/passthrough/vtd/iommu.c 
b/xen/drivers/passthrough/vtd/iommu.c
index 6a37624..31ce1af 100644
--- a/xen/drivers/passthrough/vtd/iommu.c
+++ b/xen/drivers/passthrough/vtd/iommu.c
@@ -1856,8 +1856,7 @@ static int rmrr_identity_mapping(struct domain *d, bool_t 
map,
 
     while ( base_pfn < end_pfn )
     {
-        int err = intel_iommu_map_page(d, base_pfn, base_pfn,
-                                       IOMMUF_readable|IOMMUF_writable);
+        int err = set_identity_p2m_entry(d, base_pfn, p2m_access_rw);
 
         if ( err )
             return err;
-- 
1.9.1


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