[PATCH v3 2/6] iommu/vt-d: Add set domain DOMAIN_ATTR_NESTING attr

[Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>]

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.sun@xxxxxxxxxxxxxxx>
Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
---
 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 c93fe716e6b0..2b5a47584baf 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])
@@ -5635,6 +5641,24 @@ 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)
@@ -6013,10 +6037,42 @@ 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