> -----Original Message----- > From: David Woodhouse [mailto:dw...@infradead.org] > Sent: Wednesday, January 28, 2015 11:27 PM > To: Wu, Feng > Cc: t...@linutronix.de; mi...@redhat.com; h...@zytor.com; x...@kernel.org; > g...@kernel.org; pbonz...@redhat.com; j...@8bytes.org; > alex.william...@redhat.com; jiang....@linux.intel.com; eric.au...@linaro.org; > linux-ker...@vger.kernel.org; iommu@lists.linux-foundation.org; > k...@vger.kernel.org > Subject: Re: [v3 04/26] iommu, x86: Implement irq_set_vcpu_affinity for > intel_ir_chip > > On Fri, 2014-12-12 at 23:14 +0800, Feng Wu wrote: > > Implement irq_set_vcpu_affinity for intel_ir_chip. > > > > Signed-off-by: Feng Wu <feng...@intel.com> > > Reviewed-by: Jiang Liu <jiang....@linux.intel.com> > > Acked-by: David.Woodhouse <david.woodho...@intel.com> assuming a > suitable answer to... > > > + vcpu_pi_info = (struct vcpu_data *)vcpu_info; > > + memcpy(irte_pi, &ir_data->irte_entry, sizeof(struct irte)); > > + > > + irte_pi->urg = 0; > > + irte_pi->vector = vcpu_pi_info->vector; > > + irte_pi->pda_l = (vcpu_pi_info->pi_desc_addr >> > > + (32 - PDA_LOW_BIT)) & ~(-1UL << PDA_LOW_BIT); > > + irte_pi->pda_h = (vcpu_pi_info->pi_desc_addr >> 32) & > > + ~(-1UL << PDA_HIGH_BIT); > > + > > + irte_pi->__reserved_1 = 0; > > + irte_pi->__reserved_2 = 0; > > + irte_pi->__reserved_3 = 0; > > + irte_pi->__reserved_4 = 0; > > .... do we need a barrier here before we set this bit?
Thanks a lot for your Ack, David! I cannot find a reason why we need a barrier here, since 'irte_pi' is only a local variant here, the real operation to program hardware occurs in modify_irte(), in which spin lock is acquired, this means the there is an implicit barrier there. Thanks, Feng > > > + irte_pi->pst = 1; > > + > > + modify_irte(&ir_data->irq_2_iommu, (struct irte *)irte_pi); > > > -- > dwmw2 _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
