75 lines
3.1 KiB
Diff
75 lines
3.1 KiB
Diff
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References: bsc#1214718
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# Commit 817d1cd627be668c358d038f0fadbf7d24d417d3
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# Date 2024-06-18 15:14:49 +0200
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# Author Roger Pau Monné <roger.pau@citrix.com>
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# Committer Jan Beulich <jbeulich@suse.com>
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x86/irq: deal with old_cpu_mask for interrupts in movement in fixup_irqs()
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Given the current logic it's possible for ->arch.old_cpu_mask to get out of
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sync: if a CPU set in old_cpu_mask is offlined and then onlined
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again without old_cpu_mask having been updated the data in the mask will no
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longer be accurate, as when brought back online the CPU will no longer have
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old_vector configured to handle the old interrupt source.
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If there's an interrupt movement in progress, and the to be offlined CPU (which
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is the call context) is in the old_cpu_mask, clear it and update the mask, so
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it doesn't contain stale data.
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Note that when the system is going down fixup_irqs() will be called by
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smp_send_stop() from CPU 0 with a mask with only CPU 0 on it, effectively
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asking to move all interrupts to the current caller (CPU 0) which is the only
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CPU to remain online. In that case we don't care to migrate interrupts that
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are in the process of being moved, as it's likely we won't be able to move all
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interrupts to CPU 0 due to vector shortage anyway.
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Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
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Reviewed-by: Jan Beulich <jbeulich@suse.com>
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--- a/xen/arch/x86/irq.c
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+++ b/xen/arch/x86/irq.c
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@@ -2539,7 +2539,7 @@ void fixup_irqs(const cpumask_t *mask, b
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for ( irq = 0; irq < nr_irqs; irq++ )
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{
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bool break_affinity = false, set_affinity = true;
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- unsigned int vector;
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+ unsigned int vector, cpu = smp_processor_id();
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cpumask_t *affinity = this_cpu(scratch_cpumask);
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if ( irq == 2 )
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@@ -2582,6 +2582,33 @@ void fixup_irqs(const cpumask_t *mask, b
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affinity);
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}
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+ if ( desc->arch.move_in_progress &&
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+ /*
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+ * Only attempt to adjust the mask if the current CPU is going
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+ * offline, otherwise the whole system is going down and leaving
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+ * stale data in the masks is fine.
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+ */
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+ !cpu_online(cpu) &&
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+ cpumask_test_cpu(cpu, desc->arch.old_cpu_mask) )
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+ {
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+ /*
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+ * This CPU is going offline, remove it from ->arch.old_cpu_mask
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+ * and possibly release the old vector if the old mask becomes
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+ * empty.
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+ *
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+ * Note cleaning ->arch.old_cpu_mask is required if the CPU is
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+ * brought offline and then online again, as when re-onlined the
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+ * per-cpu vector table will no longer have ->arch.old_vector
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+ * setup, and hence ->arch.old_cpu_mask would be stale.
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+ */
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+ cpumask_clear_cpu(cpu, desc->arch.old_cpu_mask);
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+ if ( cpumask_empty(desc->arch.old_cpu_mask) )
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+ {
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+ desc->arch.move_in_progress = 0;
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+ release_old_vec(desc);
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+ }
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+ }
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+
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/*
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* Avoid shuffling the interrupt around as long as current target CPUs
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* are a subset of the input mask. What fixup_irqs() cares about is
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