On 02/07/2018 12:14, Wanpeng Li wrote:
> + unsigned long flags, ipi_bitmap_low = 0, ipi_bitmap_high = 0, icr = 0;
> + int cpu, apic_id, ret = 1;
> +
> + if (cpumask_empty(mask))
> + return true;
> +
> + local_irq_save(flags);
> +
> + for_each_cpu(cpu, mask) {
> + apic_id = per_cpu(x86_cpu_to_apicid, cpu);
> + if (apic_id < BITS_PER_LONG)
> + __set_bit(apic_id, &ipi_bitmap_low);
> + else if (apic_id < 2 * BITS_PER_LONG)
> + __set_bit(apic_id - BITS_PER_LONG, &ipi_bitmap_high);
> + else
> + goto ipi_mask_done;
> + }
CPU masks are themselves bitmaps made of longs, so you should be able to
avoid the loop here.
> +static void kvm_send_ipi_mask(const struct cpumask *mask, int vector)
> +{
> + if (!__send_ipi_mask(mask, vector))
> + orig_apic.send_IPI_mask(mask, vector);
> +}
> +
> +static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, int vector)
> +{
> + unsigned int this_cpu = smp_processor_id();
> + struct cpumask new_mask;
> + const struct cpumask *local_mask;
> +
> + cpumask_copy(&new_mask, mask);
> + cpumask_clear_cpu(this_cpu, &new_mask);
> + local_mask = &new_mask;
> + if (!__send_ipi_mask(local_mask, vector))
> + orig_apic.send_IPI_mask_allbutself(mask, vector);
> +}
Likewise, here it should be possible to check the highest bit in the
mask before copying it.
Paolo
