On Mon, 25 May 2015, Feng Wu wrote:
> We don't need to migrate the irqs for VT-d Posted-Interrupts here.
> When 'pst' is set in IRTE, the associated irq will be posted to
> guests instead of interrupt remapping. The destination of the
> interrupt is set in Posted-Interrupts Descriptor, and the migration
> happens during vCPU scheduling.
>
> However, we still update the cached irte here, which can be used
> when changing back to remapping mode.
>
> Signed-off-by: Feng Wu <feng...@intel.com>
> Reviewed-by: Jiang Liu <jiang....@linux.intel.com>
> Acked-by: David Woodhouse <david.woodho...@intel.com>
> ---
> drivers/iommu/intel_irq_remapping.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iommu/intel_irq_remapping.c
> b/drivers/iommu/intel_irq_remapping.c
> index 1955b09..646f4cf 100644
> --- a/drivers/iommu/intel_irq_remapping.c
> +++ b/drivers/iommu/intel_irq_remapping.c
> @@ -994,7 +994,10 @@ intel_ir_set_affinity(struct irq_data *data, const
> struct cpumask *mask,
> */
> irte->vector = cfg->vector;
> irte->dest_id = IRTE_DEST(cfg->dest_apicid);
> - modify_irte(&ir_data->irq_2_iommu, irte);
> +
> + /* 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.
Thanks,
tglx
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