x86/irq: remove offline CPUs from old CPU mask when adjusting move_cleanup_count

When adjusting move_cleanup_count to account for CPUs that are offline also
adjust old_cpu_mask, otherwise further calls to fixup_irqs() could subtract
those again and create an imbalance in move_cleanup_count.

Fixes: 472e0b74c5c4 ('x86/IRQ: deal with move cleanup count state in fixup_irqs()')
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: e63209d3ba2fd1b2f232babd14c9c679ffa7b09a
master date: 2024-06-10 10:33:22 +0200

diff --git a/xen/arch/x86/irq.c b/xen/arch/x86/irq.c
index abd6f577dd1b7b5b2d8b9c9e11b9ee83143222a1..5e6edc0905bdbb74d18be868a34c87221079ea68 100644 (file)
--- a/xen/arch/x86/irq.c
+++ b/xen/arch/x86/irq.c
@@ -2576,6 +2576,14 @@ void fixup_irqs(const cpumask_t *mask, bool verbose)
             desc->arch.move_cleanup_count -= cpumask_weight(affinity);
             if ( !desc->arch.move_cleanup_count )
                 release_old_vec(desc);
+            else
+                /*
+                 * Adjust old_cpu_mask to account for the offline CPUs,
+                 * otherwise further calls to fixup_irqs() could subtract those
+                 * again and possibly underflow the counter.
+                 */
+                cpumask_andnot(desc->arch.old_cpu_mask, desc->arch.old_cpu_mask,
+                               affinity);
         }
 
         if ( !desc->action || cpumask_subset(desc->affinity, mask) )