Ingo Molnar wrote:
> * Weidong Han <weidong.han@xxxxxxxxx> wrote:
>
>> Interrupt remapping table entry is 128bits. Currently, it only sets
>> low 64bits of irte in modify_irte and free_irte. This ignores high
>> 64bits setting of irte, that means source-id setting will be
>> ignored. This patch sets the whole 128bits of irte when modify/free
>> it. Following source-id checking patch depends on this.
>>
>> Signed-off-by: Weidong Han <weidong.han@xxxxxxxxx>
>> ---
>> drivers/pci/intr_remapping.c | 10 +++++++---
>> 1 files changed, 7 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/pci/intr_remapping.c
>> b/drivers/pci/intr_remapping.c index f5e0ea7..946e170 100644 ---
>> a/drivers/pci/intr_remapping.c +++ b/drivers/pci/intr_remapping.c
>> @@ -309,7 +309,8 @@ int modify_irte(int irq, struct irte
>> *irte_modified) index = irq_iommu->irte_index +
>> irq_iommu->sub_handle; irte = &iommu->ir_table->base[index];
>>
>> - set_64bit((unsigned long *)irte, irte_modified->low);
>> + set_64bit((unsigned long *)&irte->low, irte_modified->low);
>> + set_64bit((unsigned long *)&irte->high, irte_modified->high);
>>
>> __iommu_flush_cache(iommu, irte, sizeof(*irte));
>>
>> rc = qi_flush_iec(iommu, index, 0);
>> @@ -386,8 +387,11 @@ int free_irte(int irq)
>> irte = &iommu->ir_table->base[index];
>>
>> if (!irq_iommu->sub_handle) {
>> - for (i = 0; i < (1 << irq_iommu->irte_mask); i++)
>> - set_64bit((unsigned long *)(irte + i), 0);
>> + for (i = 0; i < (1 << irq_iommu->irte_mask); i++) {
>> + set_64bit((unsigned long *)&irte->low, 0);
>> + set_64bit((unsigned long *)&irte->high, 0);
>> + irte++;
>> + }
>
> The loop is a bit unclean. It has a side-effect on 'irte' - and
> other patterns in the driver usually treat 'irte' as a generally
> available variable.
>
> So the above code, while correct, opens up the possibility of later
> code added to this function relying on 'irte', thinking that it's
> set to "&iommu->ir_table->base[index]", and then breaking because
> 'irte' has been iterated to the end of it in certain circumstances.
>
> It's better to factor out the whole loop into a helper function,
> which does something like:
>
> int flush_entries(struct irq_2_iommu *irq_iommu)
> {
> struct irte *start, *entry, *end;
> struct intel_iommu *iommu;
> int index;
>
> if (irq_iommu->sub_handle)
> return 0;
>
> iommu = irq_iommu->iommu;
> index = irq_iommu->irte_index + irq_iommu->sub_handle;
>
> start = iommu->ir_table->base + index;
> end = start + (1 << irq_iommu->irte_mask);
>
> for (entry = start; entry < end; entry++) {
> set_64bit((unsigned long *)&entry->low, 0);
> set_64bit((unsigned long *)&entry->high, 0);
> }
>
> return qi_flush_iec(iommu, index, irq_iommu->irte_mask);
> }
>
> Note how clearer this is - the new method has one purpose and
> 'entry' is a clear iterator.
>
> ( And note how much clearer the flow of 'rc' has become as well as a
> side-effect: it is clear now that it's set to 0 when
> irq_iommu->sub_handle is still present. )
>
> Thanks,
>
> Ingo
Yes, more clearer. will update it in next version. Thanks.
Regards,
Weidong--
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