[xen master] x86/mm: no-one passes a NULL domain to init_xen_l4_slots()

[patchbot@xxxxxxx]

commit 5dc999d711a75e1a83d4b21da203d3c3197ec0e0
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Mon May 18 17:13:38 2020 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Mon May 18 17:13:38 2020 +0200

    x86/mm: no-one passes a NULL domain to init_xen_l4_slots()
    
    Drop the NULL checks - they've been introduced by commit 8d7b633ada
    ("x86/mm: Consolidate all Xen L4 slot writing into
    init_xen_l4_slots()") without giving a reason; I'm told this was done
    in anticipation of the function potentially getting called with a NULL
    argument down the road.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
 xen/arch/x86/mm.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index f2d8190b5e..dba0903c8f 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -1652,7 +1652,7 @@ static int promote_l3_table(struct page_info *page)
  * This function must write all ROOT_PAGETABLE_PV_XEN_SLOTS, to clobber any
  * values a guest may have left there from promote_l4_table().
  *
- * l4t and l4mfn are mandatory, but l4mfn doesn't need to be the mfn under
+ * l4t, l4mfn, and d are mandatory, but l4mfn doesn't need to be the mfn under
  * *l4t.  All other parameters are optional and will either fill or zero the
  * appropriate slots.  Pagetables not shared with guests will gain the
  * extended directmap.
@@ -1664,7 +1664,7 @@ void init_xen_l4_slots(l4_pgentry_t *l4t, mfn_t l4mfn,
      * PV vcpus need a shortened directmap.  HVM and Idle vcpus get the full
      * directmap.
      */
-    bool short_directmap = d && !paging_mode_external(d);
+    bool short_directmap = !paging_mode_external(d);
 
     /* Slot 256: RO M2P (if applicable). */
     l4t[l4_table_offset(RO_MPT_VIRT_START)] =
@@ -1685,10 +1685,9 @@ void init_xen_l4_slots(l4_pgentry_t *l4t, mfn_t l4mfn,
         mfn_eq(sl4mfn, INVALID_MFN) ? l4e_empty() :
         l4e_from_mfn(sl4mfn, __PAGE_HYPERVISOR_RW);
 
-    /* Slot 260: Per-domain mappings (if applicable). */
+    /* Slot 260: Per-domain mappings. */
     l4t[l4_table_offset(PERDOMAIN_VIRT_START)] =
-        d ? l4e_from_page(d->arch.perdomain_l3_pg, __PAGE_HYPERVISOR_RW)
-          : l4e_empty();
+        l4e_from_page(d->arch.perdomain_l3_pg, __PAGE_HYPERVISOR_RW);
 
     /* Slot 261-: text/data/bss, RW M2P, vmap, frametable, directmap. */
 #ifndef NDEBUG
--
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