[PATCH 3/5] iommu/vt-d: Check domain force_snooping against attached devices

[Lu Baolu]

As domain->force_snooping only impacts the devices attached with the
domain, there's no need to check against all IOMMU units. At the same
time, for a brand new domain (hasn't been attached to any device), the
force_snooping field could be set, but the attach_dev callback will
return failure if it wants to attach to a device which IOMMU has no
snoop control capability.

Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
---
 drivers/iommu/intel/pasid.h |  2 ++
 drivers/iommu/intel/iommu.c | 50 ++++++++++++++++++++++++++++++++++++-
 drivers/iommu/intel/pasid.c | 18 +++++++++++++
 3 files changed, 69 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/intel/pasid.h b/drivers/iommu/intel/pasid.h
index ab4408c824a5..583ea67fc783 100644
--- a/drivers/iommu/intel/pasid.h
+++ b/drivers/iommu/intel/pasid.h
@@ -123,4 +123,6 @@ void intel_pasid_tear_down_entry(struct intel_iommu *iommu,
 				 bool fault_ignore);
 int vcmd_alloc_pasid(struct intel_iommu *iommu, u32 *pasid);
 void vcmd_free_pasid(struct intel_iommu *iommu, u32 pasid);
+void intel_pasid_setup_page_snoop_control(struct intel_iommu *iommu,
+					  struct device *dev, u32 pasid);
 #endif /* __INTEL_PASID_H */
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 98050943d863..3c1c228f9031 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -4554,13 +4554,61 @@ static phys_addr_t intel_iommu_iova_to_phys(struct iommu_domain *domain,
 	return phys;
 }
 
+static bool domain_support_force_snooping(struct dmar_domain *domain)
+{
+	struct device_domain_info *info;
+	unsigned long flags;
+	bool support = true;
+
+	spin_lock_irqsave(&device_domain_lock, flags);
+	if (list_empty(&domain->devices))
+		goto out;
+
+	list_for_each_entry(info, &domain->devices, link) {
+		if (!ecap_sc_support(info->iommu->ecap)) {
+			support = false;
+			break;
+		}
+	}
+out:
+	spin_unlock_irqrestore(&device_domain_lock, flags);
+	return support;
+}
+
+static void domain_set_force_snooping(struct dmar_domain *domain)
+{
+	struct device_domain_info *info;
+	unsigned long flags;
+
+	/*
+	 * Second level page table supports per-PTE snoop control. The
+	 * iommu_map() interface will handle this by setting SNP bit.
+	 */
+	if (!domain_use_first_level(domain))
+		return;
+
+	spin_lock_irqsave(&device_domain_lock, flags);
+	if (list_empty(&domain->devices))
+		goto out_unlock;
+
+	list_for_each_entry(info, &domain->devices, link)
+		intel_pasid_setup_page_snoop_control(info->iommu, info->dev,
+						     PASID_RID2PASID);
+
+out_unlock:
+	spin_unlock_irqrestore(&device_domain_lock, flags);
+}
+
 static bool intel_iommu_enforce_cache_coherency(struct iommu_domain *domain)
 {
 	struct dmar_domain *dmar_domain = to_dmar_domain(domain);
 
-	if (!domain_update_iommu_snooping(NULL))
+	if (!domain_support_force_snooping(dmar_domain))
 		return false;
+
+	domain_set_force_snooping(dmar_domain);
 	dmar_domain->force_snooping = true;
+
 	return true;
 }
 
diff --git a/drivers/iommu/intel/pasid.c b/drivers/iommu/intel/pasid.c
index f8d215d85695..815c744e6a34 100644
--- a/drivers/iommu/intel/pasid.c
+++ b/drivers/iommu/intel/pasid.c
@@ -762,3 +762,21 @@ int intel_pasid_setup_pass_through(struct intel_iommu *iommu,
 
 	return 0;
 }
+
+/*
+ * Set the page snoop control for a pasid entry which has been set up.
+ */
+void intel_pasid_setup_page_snoop_control(struct intel_iommu *iommu,
+					  struct device *dev, u32 pasid)
+{
+	struct pasid_entry *pte;
+	u16 did;
+
+	pte = intel_pasid_get_entry(dev, pasid);
+	if (WARN_ON(!pte || !pasid_pte_is_present(pte)))
+		return;
+
+	pasid_set_pgsnp(pte);
+	did = pasid_get_domain_id(pte);
+	pasid_flush_caches(iommu, pte, pasid, did);
+}
-- 
2.25.1