xen: clean up xen_load_gdt

Makes the logic a bit clearer.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

1 files changed, 13 insertions, 2 deletions

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 82cd39a6cbd3..8e024554a3e1 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -301,10 +301,21 @@ static void xen_load_gdt(const struct desc_ptr *dtr)
         frames = mcs.args;
 
         for (f = 0; va < dtr->address + size; va += PAGE_SIZE, f++) {
-                frames[f] = arbitrary_virt_to_mfn((void *)va);
+                int level;
+                pte_t *ptep = lookup_address(va, &level);
+                unsigned long pfn, mfn;
+                void *virt;
+
+                BUG_ON(ptep == NULL);
+
+                pfn = pte_pfn(*ptep);
+                mfn = pfn_to_mfn(pfn);
+                virt = __va(PFN_PHYS(pfn));
+
+                frames[f] = mfn;
 
                 make_lowmem_page_readonly((void *)va);
-                make_lowmem_page_readonly(mfn_to_virt(frames[f]));
+                make_lowmem_page_readonly(virt);
         }
 
         MULTI_set_gdt(mcs.mc, frames, size / sizeof(struct desc_struct));