miscellaneous cleanup

... noticed while putting together the 16Tb support patches for x86.

Briefly, this (in order of the changes below)
- fixes an inefficiency in x86's context switch code (translations to/
  from struct page are more involved than to/from MFNs)
- drop unnecessary MFM-to-page conversions
- drop a redundant call to destroy_xen_mappings() (an indentical call
  is being made a few lines up)
- simplify a VA-to-MFN translation
- drop dead code (several occurrences)
- add a missing __init annotation

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Keir Fraser <keir@xen.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index a40a95077b..a1e16887ef 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -1512,12 +1512,12 @@ static void __context_switch(void)
                                   per_cpu(compat_gdt_table, cpu);
     if ( need_full_gdt(n) )
     {
-        struct page_info *page = virt_to_page(gdt);
+        unsigned long mfn = virt_to_mfn(gdt);
         unsigned int i;
         for ( i = 0; i < NR_RESERVED_GDT_PAGES; i++ )
             l1e_write(n->arch.perdomain_ptes +
                       FIRST_RESERVED_GDT_PAGE + i,
-                      l1e_from_page(page + i, __PAGE_HYPERVISOR));
+                      l1e_from_pfn(mfn + i, __PAGE_HYPERVISOR));
     }
 
     if ( need_full_gdt(p) &&