On Tue, 26 May 2015, Wu, Feng wrote: > > On Mon, 25 May 2015, Feng Wu wrote: > > > + > > > + /* We don't need to modify irte if the interrupt is for posting. */ > > > + if (irte->pst != 1) > > > + modify_irte(&ir_data->irq_2_iommu, irte); > > > > I don't think this is correct. ir_data->irte_entry contains the non > > posted version, which has pst == 0. > > > > You need some other way to store whether you are in posted mode or > > not. > > Yes, seems this is incorrect. Thank you for pointing this out. After more > thinking about this, I think I can do it this way: > #1. Check the 'pst' field in hardware > #2. If 'pst' is 1, we don't update the IRTE in hardware. > > However, the question is the check and update operations should be protected > by the same spinlock ' irq_2_ir_lock ', otherwise, race condition may happen.
Why? set_affinity() and vcpu_set_affinity() are serialized via irq_desc->lock. And vcpu_set_affinity() is the only way to switch from and to posted mode. So all you need is a field in intel_irq_data which captures whether posted is enabled or not. Thanks, tglx -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/