[xen staging] x86/shadow: vCPU-s never have "no mode"

[patchbot@xxxxxxx]

commit 88f7ce5f57d49f61941986aac158baeca5b9c381
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Tue Feb 24 09:16:27 2026 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Feb 24 10:29:56 2026 +0100

    x86/shadow: vCPU-s never have "no mode"
    
    With an initial mode installed by shadow_vcpu_init(), there's no need
    for sh_update_paging_modes() to deal with the "mode is still unset"
    case. Leave an assertion, though.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 xen/arch/x86/mm/shadow/common.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/xen/arch/x86/mm/shadow/common.c b/xen/arch/x86/mm/shadow/common.c
index 126523b898..e07ba6d5a7 100644
--- a/xen/arch/x86/mm/shadow/common.c
+++ b/xen/arch/x86/mm/shadow/common.c
@@ -1855,6 +1855,8 @@ static void sh_update_paging_modes(struct vcpu *v)
             make_cr3(v, mmfn);
             hvm_update_host_cr3(v);
         }
+        else if ( !old_mode )
+            ASSERT_UNREACHABLE();
         else if ( v->arch.paging.mode != old_mode )
         {
             SHADOW_PRINTK("new paging mode: %pv pe=%d gl=%u "
@@ -1863,11 +1865,10 @@ static void sh_update_paging_modes(struct vcpu *v)
                           hvm_paging_enabled(v),
                           v->arch.paging.mode->guest_levels,
                           v->arch.paging.mode->shadow.shadow_levels,
-                          old_mode ? old_mode->guest_levels : 0,
-                          old_mode ? old_mode->shadow.shadow_levels : 0);
-            if ( old_mode &&
-                 (v->arch.paging.mode->shadow.shadow_levels !=
-                  old_mode->shadow.shadow_levels) )
+                          old_mode->guest_levels,
+                          old_mode->shadow.shadow_levels);
+            if ( v->arch.paging.mode->shadow.shadow_levels !=
+                 old_mode->shadow.shadow_levels )
             {
                 /* Need to make a new monitor table for the new mode */
                 mfn_t new_mfn, old_mfn;
--
generated by git-patchbot for /home/xen/git/xen.git#staging