RE: [PATCH 1/1] iommu/hyper-v: Use helper instead of directly accessing affinity

[Michael Kelley (LINUX)]

From: Randy Dunlap <rdunlap@xxxxxxxxxxxxx> Sent: Monday, July 25, 2022 7:39 PM
> 
> On 7/25/22 17:53, Michael Kelley wrote:
> > Recent changes to solve inconsistencies in handling IRQ masks #ifdef
> > out the affinity field in irq_common_data for non-SMP configurations.
> > The current code in hyperv_irq_remapping_alloc() gets a compiler error
> > in that case.
> >
> > Fix this by using the new irq_data_update_affinity() helper, which
> > handles the non-SMP case correctly.
> >
> 
> Reported-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>

Indeed.  Apologies for omitting this originally.

> > Signed-off-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
> Tested-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
> Acked-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
> 
> Thanks.

This patch needs to go through the same tree as Samuel Holland's earlier
patch set to solve inconsistencies in handling IRQ masks on SMP and
non-SMP configs.   From what I can tell, that's the irq/irqchip-next tree.

FWIW, it appears there's another occurrence of this same kind of
problem in arch/mips/sgi-ip27/ip27-irq.c where the "affinity" field
is referenced without an #ifdef CONFIG_SMP.   Copying the MIPS maintainer
and mailing list -- this one is out of my scope to fix.

Michael

> 
> > ---
> >  drivers/iommu/hyperv-iommu.c | 4 +---
> >  1 file changed, 1 insertion(+), 3 deletions(-)
> >
> > diff --git a/drivers/iommu/hyperv-iommu.c b/drivers/iommu/hyperv-iommu.c
> > index 51bd66a..e190bb8 100644
> > --- a/drivers/iommu/hyperv-iommu.c
> > +++ b/drivers/iommu/hyperv-iommu.c
> > @@ -68,7 +68,6 @@ static int hyperv_irq_remapping_alloc(struct irq_domain
> *domain,
> >  {
> >  	struct irq_alloc_info *info = arg;
> >  	struct irq_data *irq_data;
> > -	struct irq_desc *desc;
> >  	int ret = 0;
> >
> >  	if (!info || info->type != X86_IRQ_ALLOC_TYPE_IOAPIC || nr_irqs > 1)
> > @@ -90,8 +89,7 @@ static int hyperv_irq_remapping_alloc(struct irq_domain
> *domain,
> >  	 * Hypver-V IO APIC irq affinity should be in the scope of
> >  	 * ioapic_max_cpumask because no irq remapping support.
> >  	 */
> > -	desc = irq_data_to_desc(irq_data);
> > -	cpumask_copy(desc->irq_common_data.affinity, &ioapic_max_cpumask);
> > +	irq_data_update_affinity(irq_data, &ioapic_max_cpumask);
> >
> >  	return 0;
> >  }
> 
> --
> ~Randy