Re: [PATCH 2/2] vfio: type1: conditionally check MSI remapping at irq domain level

[Mian Yousaf Kaukab]

On 03/02/2017 11:24 AM, Auger Eric wrote:
> Hi,
>
> On 02/03/2017 11:01, Mian Yousaf Kaukab wrote:
> > Check only if irq domains are available.
> >
> > Signed-off-by: Mian Yousaf Kaukab <yousaf.kaukab@xxxxxxxx>
> > ---
> >   drivers/vfio/vfio_iommu_type1.c | 5 +++--
> >   1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> > index bd6f293c4ebd..e3ed50e40ead 100644
> > --- a/drivers/vfio/vfio_iommu_type1.c
> > +++ b/drivers/vfio/vfio_iommu_type1.c
> > @@ -1287,8 +1287,9 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
> >   	INIT_LIST_HEAD(&domain->group_list);
> >   	list_add(&group->next, &domain->group_list);
> >   
> > -	msi_remap = resv_msi ? irq_domain_check_msi_remap() :
> > -				iommu_capable(bus, IOMMU_CAP_INTR_REMAP);
> > +	msi_remap = resv_msi && IS_ENABLED(CONFIG_IRQ_DOMAIN) ?
> > +			irq_domain_check_msi_remap() :
> > +			iommu_capable(bus, IOMMU_CAP_INTR_REMAP);
> Is that patch actually needed after [PATCH 1/2] irqdomain: add empty
> irq_domain_check_msi_remap. irq_domain_check_msi_remap() should be
> defined and if you follow my suggestion, would return false. Anyway in
> your case resv_msi should be false.
I agree its an overkill if resv_msi is guaranteed to be false. What I am 
unsure about is that, if iommu have IOMMU_RESV_MSI regions that would 
mean that irq domains are selected in the build. If this is not 
guaranteed, then we need to add this check.

> Thanks
>
> Eric

BR,
Yousaf