Re: [PATCH v2 1/1] iommu/vt-d: Use device numa domain if RHSA is missing

[Lu Baolu]

Hi Kevin,

On 9/4/20 10:16 AM, Tian, Kevin wrote:
> > From: Lu Baolu
> > Sent: Friday, September 4, 2020 9:03 AM
> >
> > If there are multiple NUMA domains but the RHSA is missing in ACPI/DMAR
> > table, we could default to the device NUMA domain as fall back. This could
> > also benefit a vIOMMU use case where only single vIOMMU is exposed,
> > hence
> > no RHSA will be present but device numa domain can be correct.
>
> My comment on this is not fixed. It is not restricted to single-vIOMMU situation.
> and actually this may also happen on physical platform if some FW doesn't
> provide RHSA information.

Ah, yes. I will remove this sentence since it's same for both bare metal
and virtualization.

> with that being fixed:
>
> Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>

Thank you!

Best regards,
baolu

> > Cc: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
> > Cc: Kevin Tian <kevin.tian@xxxxxxxxx>
> > Cc: Ashok Raj <ashok.raj@xxxxxxxxx>
> > Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> > ---
> >   drivers/iommu/intel/iommu.c | 37
> > +++++++++++++++++++++++++++++++++++--
> >   1 file changed, 35 insertions(+), 2 deletions(-)
> >
> > Change log:
> > v1->v2:
> >    - Add a comment as suggested by Kevin.
> >      https://lore.kernel.org/linux-
> > iommu/MWHPR11MB1645E6D6BD1EFDFA139AA37C8C520@MWHPR11MB1
> > 645.namprd11.prod.outlook.com/
> >
> > diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> > index 7f844d1c8cd9..69d5a87188f4 100644
> > --- a/drivers/iommu/intel/iommu.c
> > +++ b/drivers/iommu/intel/iommu.c
> > @@ -698,12 +698,47 @@ static int
> > domain_update_iommu_superpage(struct dmar_domain *domain,
> >   	return fls(mask);
> >   }
> >
> > +static int domain_update_device_node(struct dmar_domain *domain)
> > +{
> > +	struct device_domain_info *info;
> > +	int nid = NUMA_NO_NODE;
> > +
> > +	assert_spin_locked(&device_domain_lock);
> > +
> > +	if (list_empty(&domain->devices))
> > +		return NUMA_NO_NODE;
> > +
> > +	list_for_each_entry(info, &domain->devices, link) {
> > +		if (!info->dev)
> > +			continue;
> > +
> > +		/*
> > +		 * There could possibly be multiple device numa nodes as
> > devices
> > +		 * within the same domain may sit behind different IOMMUs.
> > There
> > +		 * isn't perfect answer in such situation, so we select first
> > +		 * come first served policy.
> > +		 */
> > +		nid = dev_to_node(info->dev);
> > +		if (nid != NUMA_NO_NODE)
> > +			break;
> > +	}
> > +
> > +	return nid;
> > +}
> > +
> >   /* Some capabilities may be different across iommus */
> >   static void domain_update_iommu_cap(struct dmar_domain *domain)
> >   {
> >   	domain_update_iommu_coherency(domain);
> >   	domain->iommu_snooping =
> > domain_update_iommu_snooping(NULL);
> >   	domain->iommu_superpage =
> > domain_update_iommu_superpage(domain, NULL);
> > +
> > +	/*
> > +	 * If RHSA is missing, we should default to the device numa domain
> > +	 * as fall back.
> > +	 */
> > +	if (domain->nid == NUMA_NO_NODE)
> > +		domain->nid = domain_update_device_node(domain);
> >   }
> >
> >   struct context_entry *iommu_context_addr(struct intel_iommu *iommu, u8
> > bus,
> > @@ -5096,8 +5131,6 @@ static struct iommu_domain
> > *intel_iommu_domain_alloc(unsigned type)
> >   		if (type == IOMMU_DOMAIN_DMA)
> >   			intel_init_iova_domain(dmar_domain);
> >
> > -		domain_update_iommu_cap(dmar_domain);
> > -
> >   		domain = &dmar_domain->domain;
> >   		domain->geometry.aperture_start = 0;
> >   		domain->geometry.aperture_end   =
> > --
> > 2.17.1
> >
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