xen/arm: allow translated iommu mappings

In preparation of exposing vITS to domUs, generalize arm_iommu_map_page
and arm_iommu_unmap_page to allow ITS doorbell mappings with dfn != mfn.

The mfn does not need to be passed to guest_physmap_remove_page since
there is no mfn checking on the p2m_iommu_map_{rw,ro} p2m types during
unmap. Pass INVALID_MFN to guest_physmap_remove_page.

Signed-off-by: Stefano Stabellini <stefano.stabellini@amd.com>
Signed-off-by: Stewart Hildebrand <stewart.hildebrand@amd.com>
Tested-by: Jason Andryuk <jason.andryuk@amd.com>
Reviewed-by: Julien Grall <jgrall@amazon.com>

xen/drivers/passthrough/arm/iommu_helpers.c

@@ -36,9 +36,6 @@ int __must_check arm_iommu_map_page(struct domain *d, dfn_t dfn, mfn_t mfn,
 {
     p2m_type_t t;
 
-    BUG_ON(!domain_use_host_layout(d));
-    BUG_ON(mfn_x(mfn) != dfn_x(dfn));
-
     /* We only support readable and writable flags */
     if ( !(flags & (IOMMUF_readable | IOMMUF_writable)) )
         return -EINVAL;
@@ -49,7 +46,7 @@ int __must_check arm_iommu_map_page(struct domain *d, dfn_t dfn, mfn_t mfn,
      * The function guest_physmap_add_entry replaces the current mapping
      * if there is already one...
      */
-    return guest_physmap_add_entry(d, _gfn(dfn_x(dfn)), _mfn(dfn_x(dfn)),
+    return guest_physmap_add_entry(d, _gfn(dfn_x(dfn)), mfn,
                                    IOMMUF_order(flags), t);
 }
 
@@ -58,11 +55,7 @@ int __must_check arm_iommu_unmap_page(struct domain *d, dfn_t dfn,
                                       unsigned int order,
                                       unsigned int *flush_flags)
 {
-    if ( !domain_use_host_layout(d) )
-        return -EINVAL;
-
-    return guest_physmap_remove_page(d, _gfn(dfn_x(dfn)), _mfn(dfn_x(dfn)),
-                                     order);
+    return guest_physmap_remove_page(d, _gfn(dfn_x(dfn)), INVALID_MFN, order);
 }
 
 /*