Re: [PATCH v6 06/15] iommu/vt-d: Support setting ioasid set to domain

Auger Eric
2020-08-13T15:07:15Z

Hi Yi,

On 7/28/20 8:27 AM, Liu Yi L wrote:
> From IOMMU p.o.v., PASIDs allocated and managed by external components
> (e.g. VFIO) will be passed in for gpasid_bind/unbind operation. IOMMU
> needs some knowledge to check the PASID ownership, hence add an interface
> for those components to tell the PASID owner.
>
> In latest kernel design, PASID ownership is managed by IOASID set where
> the PASID is allocated from. This patch adds support for setting ioasid
> set ID to the domains used for nesting/vSVA. Subsequent SVA operations
> will check the PASID against its IOASID set for proper ownership.
>
> Cc: Kevin Tian <kevin.tian@intel.com>
> CC: Jacob Pan <jacob.jun.pan@linux.intel.com>
> Cc: Alex Williamson <alex.williamson@redhat.com>
> Cc: Eric Auger <eric.auger@redhat.com>
> Cc: Jean-Philippe Brucker <jean-philippe@linaro.org>
> Cc: Joerg Roedel <joro@8bytes.org>
> Cc: Lu Baolu <baolu.lu@linux.intel.com>
> Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> ---
> v5 -> v6:
> *) address comments against v5 from Eric Auger.
>
> v4 -> v5:
> *) address comments from Eric Auger.
> ---
> drivers/iommu/intel/iommu.c | 23 +++++++++++++++++++++++
> include/linux/intel-iommu.h | 4 ++++
> include/linux/iommu.h | 1 +
> 3 files changed, 28 insertions(+)
>
> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> index ed4b71c..b2fe54e 100644
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -1793,6 +1793,7 @@ static struct dmar_domain *alloc_domain(int flags)
> if (first_level_by_default())
> domain->flags |= DOMAIN_FLAG_USE_FIRST_LEVEL;
> domain->has_iotlb_device = false;
> + domain->ioasid_sid = INVALID_IOASID_SET;
> INIT_LIST_HEAD(&domain->devices);
>
> return domain;
> @@ -6040,6 +6041,28 @@ intel_iommu_domain_set_attr(struct iommu_domain *domain,
> }
> spin_unlock_irqrestore(&device_domain_lock, flags);
> break;
> + case DOMAIN_ATTR_IOASID_SID:
> + {
> + int sid = *(int *)data;

> +
> + spin_lock_irqsave(&device_domain_lock, flags);
> + if (!(dmar_domain->flags & DOMAIN_FLAG_NESTING_MODE)) {
> + ret = -ENODEV;
> + spin_unlock_irqrestore(&device_domain_lock, flags);
> + break;
> + }
> + if (dmar_domain->ioasid_sid != INVALID_IOASID_SET &&
> + dmar_domain->ioasid_sid != sid) {
> + pr_warn_ratelimited("multi ioasid_set (%d:%d) setting",
> + dmar_domain->ioasid_sid, sid);
> + ret = -EBUSY;
> + spin_unlock_irqrestore(&device_domain_lock, flags);
> + break;
> + }
> + dmar_domain->ioasid_sid = sid;
> + spin_unlock_irqrestore(&device_domain_lock, flags);
> + break;
nit: Adding a small helper
int__set_ioasid_sid(struct dmar_domain *dmar_domain, int sid_id)

may simplify the lock handling

> + }
> default:
> ret = -EINVAL;
> break;
> diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
> index 3f23c26..0d0ab32 100644
> --- a/include/linux/intel-iommu.h
> +++ b/include/linux/intel-iommu.h
> @@ -549,6 +549,10 @@ struct dmar_domain {
> 2 == 1GiB, 3 == 512GiB, 4 == 1TiB */
> u64 max_addr; /* maximum mapped address */
>
> + int ioasid_sid; /*
> + * the ioasid set which tracks all
id of the ioasid set?
> + * PASIDs used by the domain.
> + */
> int default_pasid; /*
> * The default pasid used for non-SVM
> * traffic on mediated devices.
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 4a02c9e..b1ff702 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -124,6 +124,7 @@ enum iommu_attr {
> DOMAIN_ATTR_FSL_PAMUV1,
> DOMAIN_ATTR_NESTING, /* two stages of translation */
> DOMAIN_ATTR_DMA_USE_FLUSH_QUEUE,
> + DOMAIN_ATTR_IOASID_SID,
> DOMAIN_ATTR_MAX,
> };
>
>
Besides
Reviewed-by: Eric Auger <eric.auger@redhat.com>

Eric