This adds the Intel VT-d specific callback of setting
DOMAIN_ATTR_NESTING domain attribution. It is necessary
to let the VT-d driver know that the domain represents
a virtual machine which requires the IOMMU hardware to
support nested translation mode. Return success if the
IOMMU hardware suports nested mode, otherwise failure.

Signed-off-by: Yi Sun <yi.y....@linux.intel.com>
Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 drivers/iommu/intel-iommu.c | 56 +++++++++++++++++++++++++++++++++++++
 1 file changed, 56 insertions(+)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 71ad5e5feae2..35f65628202c 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -315,6 +315,12 @@ static int hw_pass_through = 1;
  */
 #define DOMAIN_FLAG_USE_FIRST_LEVEL            BIT(2)
 
+/*
+ * Domain represents a virtual machine which demands iommu nested
+ * translation mode support.
+ */
+#define DOMAIN_FLAG_NESTING_MODE               BIT(3)
+
 #define for_each_domain_iommu(idx, domain)                     \
        for (idx = 0; idx < g_num_of_iommus; idx++)             \
                if (domain->iommu_refcnt[idx])
@@ -5640,6 +5646,24 @@ static inline bool iommu_pasid_support(void)
        return ret;
 }
 
+static inline bool nested_mode_support(void)
+{
+       struct dmar_drhd_unit *drhd;
+       struct intel_iommu *iommu;
+       bool ret = true;
+
+       rcu_read_lock();
+       for_each_active_iommu(iommu, drhd) {
+               if (!sm_supported(iommu) || !ecap_nest(iommu->ecap)) {
+                       ret = false;
+                       break;
+               }
+       }
+       rcu_read_unlock();
+
+       return ret;
+}
+
 static bool intel_iommu_capable(enum iommu_cap cap)
 {
        if (cap == IOMMU_CAP_CACHE_COHERENCY)
@@ -6018,10 +6042,42 @@ static bool intel_iommu_is_attach_deferred(struct 
iommu_domain *domain,
        return dev->archdata.iommu == DEFER_DEVICE_DOMAIN_INFO;
 }
 
+static int
+intel_iommu_domain_set_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 = 0;
+
+       if (domain->type != IOMMU_DOMAIN_UNMANAGED)
+               return -EINVAL;
+
+       switch (attr) {
+       case DOMAIN_ATTR_NESTING:
+               spin_lock_irqsave(&device_domain_lock, flags);
+               if (nested_mode_support() &&
+                   list_empty(&dmar_domain->devices)) {
+                       dmar_domain->flags |= DOMAIN_FLAG_NESTING_MODE;
+                       dmar_domain->flags &= ~DOMAIN_FLAG_USE_FIRST_LEVEL;
+               } else {
+                       ret = -ENODEV;
+               }
+               spin_unlock_irqrestore(&device_domain_lock, flags);
+               break;
+       default:
+               ret = -EINVAL;
+               break;
+       }
+
+       return ret;
+}
+
 const struct iommu_ops intel_iommu_ops = {
        .capable                = intel_iommu_capable,
        .domain_alloc           = intel_iommu_domain_alloc,
        .domain_free            = intel_iommu_domain_free,
+       .domain_set_attr        = intel_iommu_domain_set_attr,
        .attach_dev             = intel_iommu_attach_device,
        .detach_dev             = intel_iommu_detach_device,
        .aux_attach_dev         = intel_iommu_aux_attach_device,
-- 
2.17.1

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