With subdevice information opt-in through iommu_ops.aux_at(de)tach_dev()
interfaces, the vendor iommu driver is able to learn the knowledge about
the relationships between the subdevices and the aux-domains. Implement
is_aux_domain() support based on the relationship knowledges.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 drivers/iommu/intel/iommu.c | 125 ++++++++++++++++++++++++++----------
 include/linux/intel-iommu.h |  17 +++--
 2 files changed, 103 insertions(+), 39 deletions(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 3c12fd06856c..50431c7b2e71 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -334,6 +334,8 @@ static int intel_iommu_attach_device(struct iommu_domain 
*domain,
                                     struct device *dev);
 static phys_addr_t intel_iommu_iova_to_phys(struct iommu_domain *domain,
                                            dma_addr_t iova);
+static bool intel_iommu_dev_feat_enabled(struct device *dev,
+                                        enum iommu_dev_features feat);
 
 #ifdef CONFIG_INTEL_IOMMU_DEFAULT_ON
 int dmar_disabled = 0;
@@ -1832,6 +1834,7 @@ static struct dmar_domain *alloc_domain(int flags)
                domain->flags |= DOMAIN_FLAG_USE_FIRST_LEVEL;
        domain->has_iotlb_device = false;
        INIT_LIST_HEAD(&domain->devices);
+       INIT_LIST_HEAD(&domain->subdevices);
 
        return domain;
 }
@@ -2580,7 +2583,7 @@ static struct dmar_domain 
*dmar_insert_one_dev_info(struct intel_iommu *iommu,
        info->iommu = iommu;
        info->pasid_table = NULL;
        info->auxd_enabled = 0;
-       INIT_LIST_HEAD(&info->auxiliary_domains);
+       INIT_LIST_HEAD(&info->subdevices);
 
        if (dev && dev_is_pci(dev)) {
                struct pci_dev *pdev = to_pci_dev(info->dev);
@@ -5137,21 +5140,28 @@ static void intel_iommu_domain_free(struct iommu_domain 
*domain)
                domain_exit(to_dmar_domain(domain));
 }
 
-/*
- * Check whether a @domain could be attached to the @dev through the
- * aux-domain attach/detach APIs.
- */
-static inline bool
-is_aux_domain(struct device *dev, struct iommu_domain *domain)
+/* Lookup subdev_info in the domain's subdevice siblings. */
+static struct subdev_info *
+subdev_lookup_domain(struct dmar_domain *domain, struct device *dev,
+                    struct device *subdev)
 {
-       struct device_domain_info *info = get_domain_info(dev);
+       struct subdev_info *sinfo = NULL, *tmp;
 
-       return info && info->auxd_enabled &&
-                       domain->type == IOMMU_DOMAIN_UNMANAGED;
+       assert_spin_locked(&device_domain_lock);
+
+       list_for_each_entry(tmp, &domain->subdevices, link_domain) {
+               if ((!dev || tmp->pdev == dev) && tmp->dev == subdev) {
+                       sinfo = tmp;
+                       break;
+               }
+       }
+
+       return sinfo;
 }
 
-static void auxiliary_link_device(struct dmar_domain *domain,
-                                 struct device *dev)
+static void
+subdev_link_device(struct dmar_domain *domain, struct device *dev,
+                  struct subdev_info *sinfo)
 {
        struct device_domain_info *info = get_domain_info(dev);
 
@@ -5159,12 +5169,13 @@ static void auxiliary_link_device(struct dmar_domain 
*domain,
        if (WARN_ON(!info))
                return;
 
-       domain->auxd_refcnt++;
-       list_add(&domain->auxd, &info->auxiliary_domains);
+       list_add(&info->subdevices, &sinfo->link_phys);
+       list_add(&domain->subdevices, &sinfo->link_domain);
 }
 
-static void auxiliary_unlink_device(struct dmar_domain *domain,
-                                   struct device *dev)
+static void
+subdev_unlink_device(struct dmar_domain *domain, struct device *dev,
+                    struct subdev_info *sinfo)
 {
        struct device_domain_info *info = get_domain_info(dev);
 
@@ -5172,24 +5183,30 @@ static void auxiliary_unlink_device(struct dmar_domain 
*domain,
        if (WARN_ON(!info))
                return;
 
-       list_del(&domain->auxd);
-       domain->auxd_refcnt--;
+       list_del(&sinfo->link_phys);
+       list_del(&sinfo->link_domain);
+       kfree(sinfo);
 
-       if (!domain->auxd_refcnt && domain->default_pasid > 0)
+       if (list_empty(&domain->subdevices) && domain->default_pasid > 0)
                ioasid_free(domain->default_pasid);
 }
 
-static int aux_domain_add_dev(struct dmar_domain *domain,
-                             struct device *dev)
+static int aux_domain_add_dev(struct dmar_domain *domain, struct device *dev,
+                             struct device *subdev)
 {
        int ret;
        unsigned long flags;
        struct intel_iommu *iommu;
+       struct subdev_info *sinfo;
 
        iommu = device_to_iommu(dev, NULL, NULL);
        if (!iommu)
                return -ENODEV;
 
+       sinfo = kzalloc(sizeof(*sinfo), GFP_KERNEL);
+       if (!sinfo)
+               return -ENOMEM;
+
        if (domain->default_pasid <= 0) {
                int pasid;
 
@@ -5199,7 +5216,8 @@ static int aux_domain_add_dev(struct dmar_domain *domain,
                                     NULL);
                if (pasid == INVALID_IOASID) {
                        pr_err("Can't allocate default pasid\n");
-                       return -ENODEV;
+                       ret = -ENODEV;
+                       goto pasid_failed;
                }
                domain->default_pasid = pasid;
        }
@@ -5225,7 +5243,10 @@ static int aux_domain_add_dev(struct dmar_domain *domain,
                goto table_failed;
        spin_unlock(&iommu->lock);
 
-       auxiliary_link_device(domain, dev);
+       sinfo->dev = subdev;
+       sinfo->domain = domain;
+       sinfo->pdev = dev;
+       subdev_link_device(domain, dev, sinfo);
 
        spin_unlock_irqrestore(&device_domain_lock, flags);
 
@@ -5236,27 +5257,36 @@ static int aux_domain_add_dev(struct dmar_domain 
*domain,
 attach_failed:
        spin_unlock(&iommu->lock);
        spin_unlock_irqrestore(&device_domain_lock, flags);
-       if (!domain->auxd_refcnt && domain->default_pasid > 0)
+       if (list_empty(&domain->subdevices) && domain->default_pasid > 0)
                ioasid_free(domain->default_pasid);
+pasid_failed:
+       kfree(sinfo);
 
        return ret;
 }
 
-static void aux_domain_remove_dev(struct dmar_domain *domain,
-                                 struct device *dev)
+static void
+aux_domain_remove_dev(struct dmar_domain *domain, struct device *dev,
+                     struct device *subdev)
 {
        struct device_domain_info *info;
        struct intel_iommu *iommu;
+       struct subdev_info *sinfo;
        unsigned long flags;
 
-       if (!is_aux_domain(dev, &domain->domain))
+       if (!intel_iommu_dev_feat_enabled(dev, IOMMU_DEV_FEAT_AUX) ||
+           domain->domain.type != IOMMU_DOMAIN_UNMANAGED)
                return;
 
        spin_lock_irqsave(&device_domain_lock, flags);
        info = get_domain_info(dev);
        iommu = info->iommu;
-
-       auxiliary_unlink_device(domain, dev);
+       sinfo = subdev_lookup_domain(domain, dev, subdev);
+       if (!sinfo) {
+               spin_unlock_irqrestore(&device_domain_lock, flags);
+               return;
+       }
+       subdev_unlink_device(domain, dev, sinfo);
 
        spin_lock(&iommu->lock);
        intel_pasid_tear_down_entry(iommu, dev, domain->default_pasid, false);
@@ -5319,7 +5349,8 @@ static int intel_iommu_attach_device(struct iommu_domain 
*domain,
                return -EPERM;
        }
 
-       if (is_aux_domain(dev, domain))
+       if (intel_iommu_dev_feat_enabled(dev, IOMMU_DEV_FEAT_AUX) &&
+           domain->type == IOMMU_DOMAIN_UNMANAGED)
                return -EPERM;
 
        /* normally dev is not mapped */
@@ -5344,14 +5375,15 @@ intel_iommu_aux_attach_device(struct iommu_domain 
*domain,
 {
        int ret;
 
-       if (!is_aux_domain(dev, domain))
+       if (!intel_iommu_dev_feat_enabled(dev, IOMMU_DEV_FEAT_AUX) ||
+           domain->type != IOMMU_DOMAIN_UNMANAGED)
                return -EPERM;
 
        ret = prepare_domain_attach_device(domain, dev);
        if (ret)
                return ret;
 
-       return aux_domain_add_dev(to_dmar_domain(domain), dev);
+       return aux_domain_add_dev(to_dmar_domain(domain), dev, subdev);
 }
 
 static void intel_iommu_detach_device(struct iommu_domain *domain,
@@ -5364,7 +5396,7 @@ static void
 intel_iommu_aux_detach_device(struct iommu_domain *domain, struct device *dev,
                              struct device *subdev)
 {
-       aux_domain_remove_dev(to_dmar_domain(domain), dev);
+       aux_domain_remove_dev(to_dmar_domain(domain), dev, subdev);
 }
 
 /*
@@ -6020,6 +6052,32 @@ static bool intel_iommu_is_attach_deferred(struct 
iommu_domain *domain,
        return attach_deferred(dev);
 }
 
+static int
+intel_iommu_domain_get_attr(struct iommu_domain *domain,
+                           enum iommu_attr attr, void *data)
+{
+       struct dmar_domain *dmar_domain = to_dmar_domain(domain);
+       unsigned long flags;
+       int ret;
+
+       if (domain->type != IOMMU_DOMAIN_UNMANAGED)
+               return -EINVAL;
+
+       switch (attr) {
+       case DOMAIN_ATTR_IS_AUX:
+               spin_lock_irqsave(&device_domain_lock, flags);
+               ret = !IS_ERR_OR_NULL(subdev_lookup_domain(dmar_domain,
+                                                          NULL, data));
+               spin_unlock_irqrestore(&device_domain_lock, flags);
+               break;
+       default:
+               ret = -EINVAL;
+               break;
+       }
+
+       return ret;
+}
+
 static int
 intel_iommu_domain_set_attr(struct iommu_domain *domain,
                            enum iommu_attr attr, void *data)
@@ -6073,6 +6131,7 @@ const struct iommu_ops intel_iommu_ops = {
        .domain_alloc           = intel_iommu_domain_alloc,
        .domain_free            = intel_iommu_domain_free,
        .domain_set_attr        = intel_iommu_domain_set_attr,
+       .domain_get_attr        = intel_iommu_domain_get_attr,
        .attach_dev             = intel_iommu_attach_device,
        .detach_dev             = intel_iommu_detach_device,
        .aux_attach_dev         = intel_iommu_aux_attach_device,
diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
index b1ed2f25f7c0..47ba1904c691 100644
--- a/include/linux/intel-iommu.h
+++ b/include/linux/intel-iommu.h
@@ -526,11 +526,9 @@ struct dmar_domain {
                                        /* Domain ids per IOMMU. Use u16 since
                                         * domain ids are 16 bit wide according
                                         * to VT-d spec, section 9.3 */
-       unsigned int    auxd_refcnt;    /* Refcount of auxiliary attaching */
-
        bool has_iotlb_device;
        struct list_head devices;       /* all devices' list */
-       struct list_head auxd;          /* link to device's auxiliary list */
+       struct list_head subdevices;    /* all subdevices' list */
        struct iova_domain iovad;       /* iova's that belong to this domain */
 
        struct dma_pte  *pgd;           /* virtual address */
@@ -603,14 +601,21 @@ struct intel_iommu {
        struct dmar_drhd_unit *drhd;
 };
 
+/* Per subdevice private data */
+struct subdev_info {
+       struct list_head link_phys;     /* link to phys device siblings */
+       struct list_head link_domain;   /* link to domain siblings */
+       struct device *pdev;            /* physical device derived from */
+       struct device *dev;             /* subdevice node */
+       struct dmar_domain *domain;     /* aux-domain */
+};
+
 /* PCI domain-device relationship */
 struct device_domain_info {
        struct list_head link;  /* link to domain siblings */
        struct list_head global; /* link to global list */
        struct list_head table; /* link to pasid table */
-       struct list_head auxiliary_domains; /* auxiliary domains
-                                            * attached to this device
-                                            */
+       struct list_head subdevices; /* subdevices sibling */
        u32 segment;            /* PCI segment number */
        u8 bus;                 /* PCI bus number */
        u8 devfn;               /* PCI devfn number */
-- 
2.17.1

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