* 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
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