[xen master] x86/mm: fix alignment check for non-present entries

[patchbot@xxxxxxx]

commit b1ebb6461a027f07e4a844cae348fbd9cfabe984
Author:     Roger Pau Monné <roger.pau@xxxxxxxxxx>
AuthorDate: Fri Nov 15 14:14:12 2024 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Nov 15 14:14:12 2024 +0100

    x86/mm: fix alignment check for non-present entries
    
    While the alignment of the mfn is not relevant for non-present entries, the
    alignment of the linear address is.  Commit 5b52e1b0436f introduced a
    regression by not checking the alignment of the linear address when the new
    entry was a non-present one.
    
    Fix by always checking the alignment of the linear address, non-present 
entries
    must just skip the alignment check of the physical address.
    
    Fixes: 5b52e1b0436f ('x86/mm: skip super-page alignment checks for 
non-present entries')
    Reported-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Suggested-by: Jan Beulich <jbeulich@xxxxxxxx>
    Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/arch/x86/mm.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index 5d7e8d7871..494c14e80f 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -5525,7 +5525,7 @@ int map_pages_to_xen(
         ol3e = *pl3e;
 
         if ( cpu_has_page1gb &&
-             (!(flags & _PAGE_PRESENT) || IS_L3E_ALIGNED(virt, mfn)) &&
+             IS_L3E_ALIGNED(virt, flags & _PAGE_PRESENT ? mfn : _mfn(0)) &&
              nr_mfns >= (1UL << (L3_PAGETABLE_SHIFT - PAGE_SHIFT)) &&
              !(flags & (_PAGE_PAT | MAP_SMALL_PAGES)) )
         {
@@ -5644,7 +5644,7 @@ int map_pages_to_xen(
         if ( !pl2e )
             goto out;
 
-        if ( (!(flags & _PAGE_PRESENT) || IS_L2E_ALIGNED(virt, mfn)) &&
+        if ( IS_L2E_ALIGNED(virt, flags & _PAGE_PRESENT ? mfn : _mfn(0)) &&
              (nr_mfns >= (1u << PAGETABLE_ORDER)) &&
              !(flags & (_PAGE_PAT|MAP_SMALL_PAGES)) )
         {
--
generated by git-patchbot for /home/xen/git/xen.git#master