[xen staging] ARM/vgic: Use for_each_set_bit() in vgic_sync_from_lrs()

[patchbot@xxxxxxx]

commit b4fd29dfe1f8114f5b978a5f8307ba37f1d9595d
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Wed Feb 25 13:20:12 2026 +0000
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Tue May 5 11:45:00 2026 +0100

    ARM/vgic: Use for_each_set_bit() in vgic_sync_from_lrs()
    
    lr_mask doesn't have bits set beyond the hardware limit, with the upper bits
    remaining zero.  Therefore, for_each_set_bit() is a better option.
    
    For ARM64, bloat-o-meter reports:
    
      Function                                     old     new   delta
      vgic_sync_from_lrs                           208     168     -40
    
    but this doesn't highlight that it also removes a call to find_next_bit() 
from
    each loop iteration.
    
    No functional change.
    
    Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Reviewed-by: Michal Orzel <michal.orzel@xxxxxxx>
    Acked-by: Julien Grall <julien@xxxxxxx>
---
 xen/arch/arm/gic-vgic.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/xen/arch/arm/gic-vgic.c b/xen/arch/arm/gic-vgic.c
index ea48c5375a..fae80e6cd2 100644
--- a/xen/arch/arm/gic-vgic.c
+++ b/xen/arch/arm/gic-vgic.c
@@ -241,9 +241,7 @@ static void gic_update_one_lr(struct vcpu *v, int i)
 
 void vgic_sync_from_lrs(struct vcpu *v)
 {
-    int i = 0;
     unsigned long flags;
-    unsigned int nr_lrs = gic_get_nr_lrs();
 
     /* The idle domain has no LRs to be cleared. Since gic_restore_state
      * doesn't write any LR registers for the idle domain they could be
@@ -255,11 +253,8 @@ void vgic_sync_from_lrs(struct vcpu *v)
 
     spin_lock_irqsave(&v->arch.vgic.lock, flags);
 
-    while ((i = find_next_bit((const unsigned long *) &this_cpu(lr_mask),
-                              nr_lrs, i)) < nr_lrs ) {
+    for_each_set_bit ( i, this_cpu(lr_mask) )
         gic_update_one_lr(v, i);
-        i++;
-    }
 
     spin_unlock_irqrestore(&v->arch.vgic.lock, flags);
 }
--
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