On 2021/3/15 16:30, Marc Zyngier wrote:
> On 2021-03-13 08:38, Shenming Lu wrote:
>> From: Zenghui Yu <yuzenghui@xxxxxxxxxx>
>>
>> When setting the forwarding path of a VLPI (switch to the HW mode),
>> we can also transfer the pending state from irq->pending_latch to
>> VPT (especially in migration, the pending states of VLPIs are restored
>> into kvm’s vgic first). And we currently send "INT+VSYNC" to trigger
>> a VLPI to pending.
>>
>> Signed-off-by: Zenghui Yu <yuzenghui@xxxxxxxxxx>
>> Signed-off-by: Shenming Lu <lushenming@xxxxxxxxxx>
>> ---
>> arch/arm64/kvm/vgic/vgic-v4.c | 18 ++++++++++++++++++
>> 1 file changed, 18 insertions(+)
>>
>> diff --git a/arch/arm64/kvm/vgic/vgic-v4.c b/arch/arm64/kvm/vgic/vgic-v4.c
>> index ac029ba3d337..3b82ab80c2f3 100644
>> --- a/arch/arm64/kvm/vgic/vgic-v4.c
>> +++ b/arch/arm64/kvm/vgic/vgic-v4.c
>> @@ -449,6 +449,24 @@ int kvm_vgic_v4_set_forwarding(struct kvm *kvm, int virq,
>> irq->host_irq = virq;
>> atomic_inc(&map.vpe->vlpi_count);
>>
>> + /* Transfer pending state */
>> + if (irq->pending_latch) {
>> + unsigned long flags;
>> +
>> + ret = irq_set_irqchip_state(irq->host_irq,
>> + IRQCHIP_STATE_PENDING,
>> + irq->pending_latch);
>> + WARN_RATELIMIT(ret, "IRQ %d", irq->host_irq);
>> +
>> + /*
>> + * Clear pending_latch and communicate this state
>> + * change via vgic_queue_irq_unlock.
>> + */
>> + raw_spin_lock_irqsave(&irq->irq_lock, flags);
>> + irq->pending_latch = false;
>> + vgic_queue_irq_unlock(kvm, irq, flags);
>> + }
>> +
>> out:
>> mutex_unlock(&its->its_lock);
>> return ret;
>
> The read side of the pending state isn't locked, but the write side is.
> I'd rather you lock the whole sequence for peace of mind.
Did you mean to lock before emitting the mapping request, Or just before reading
the pending state?
Thanks,
Shenming
>
> Thanks,
>
> M.
