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Re: [Xen-devel] [PATCH] x86/mm: free_page_type() is PV-only



Hi Jan,

Thank you for sending the patch! I will rebase my M2P series on top of this.

Cheers,

On 10/05/2019 15:12, Jan Beulich wrote:
While it already has a CONFIG_PV wrapped around its entire body, it is
still uselessly invoking mfn_to_gmfn(), which is about to be replaced.
Avoid morphing this code into even more suspicious shape and remove the
effectively dead code - translated mode has been made impossible for PV
quite some time ago.

Adjust and extend the assertions at the same time: The original
ASSERT(!shadow_mode_refcounts(owner)) really means
ASSERT(!shadow_mode_enabled(owner) || !paging_mode_refcounts(owner)),
which isn't what we want here.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -2632,7 +2632,6 @@ int free_page_type(struct page_info *pag
  {
  #ifdef CONFIG_PV
      struct domain *owner = page_get_owner(page);
-    unsigned long gmfn;
      int rc;
if ( likely(owner != NULL) && unlikely(paging_mode_enabled(owner)) )
@@ -2640,11 +2639,11 @@ int free_page_type(struct page_info *pag
          /* A page table is dirtied when its type count becomes zero. */
          paging_mark_dirty(owner, page_to_mfn(page));
- ASSERT(!shadow_mode_refcounts(owner));
+        ASSERT(shadow_mode_enabled(owner));
+        ASSERT(!paging_mode_refcounts(owner));
+        ASSERT(!paging_mode_translate(owner));
- gmfn = mfn_to_gmfn(owner, mfn_x(page_to_mfn(page)));
-        if ( VALID_M2P(gmfn) )
-            shadow_remove_all_shadows(owner, _mfn(gmfn));
+        shadow_remove_all_shadows(owner, page_to_mfn(page));
      }
if ( !(type & PGT_partial) )





--
Julien Grall

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