[xen staging] x86: simplify is_guest_l2_slot()

[patchbot@xxxxxxx]

commit 8cf225013582723275f0d60f1107319f5963af7f
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Fri Sep 4 10:59:33 2020 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Sep 4 10:59:33 2020 +0200

    x86: simplify is_guest_l2_slot()
    
    is_pv_32bit_domain() has become expensive, and its use here is
    redundant: Only 32-bit guests would ever get PGT_pae_xen_l2 set on
    their L2 page table pages anyway. (If some other error does lead to
    PGT_pae_xen_l2 ending up anywhere else, we still don't want to allow a
    guest to control the entries.)
    
    Suggested-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 xen/include/asm-x86/x86_64/page.h | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/xen/include/asm-x86/x86_64/page.h 
b/xen/include/asm-x86/x86_64/page.h
index 26621f9519..60db28f4e7 100644
--- a/xen/include/asm-x86/x86_64/page.h
+++ b/xen/include/asm-x86/x86_64/page.h
@@ -106,8 +106,7 @@ typedef l4_pgentry_t root_pgentry_t;
 #define l4_linear_offset(_a) (((_a) & VADDR_MASK) >> L4_PAGETABLE_SHIFT)
 
 #define is_guest_l2_slot(_d, _t, _s)                   \
-    ( !is_pv_32bit_domain(_d) ||                       \
-      !((_t) & PGT_pae_xen_l2) ||                      \
+    ( !((_t) & PGT_pae_xen_l2) ||                      \
       ((_s) < COMPAT_L2_PAGETABLE_FIRST_XEN_SLOT(_d)) )
 #define is_guest_l4_slot(_d, _s)                    \
     ( is_pv_32bit_domain(_d)                        \
--
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