[PATCH v2 2/4] 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>
---
 include/linux/intel-iommu.h |  1 +
 drivers/iommu/intel/pasid.h |  2 ++
 drivers/iommu/intel/iommu.c | 51 ++++++++++++++++++++++++++++++++++---
 drivers/iommu/intel/pasid.c | 23 +++++++++++++++++
 4 files changed, 74 insertions(+), 3 deletions(-)

diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
index 72e5d7900e71..4f29139bbfc3 100644
--- a/include/linux/intel-iommu.h
+++ b/include/linux/intel-iommu.h
@@ -540,6 +540,7 @@ struct dmar_domain {
 	u8 has_iotlb_device: 1;
 	u8 iommu_coherency: 1;		/* indicate coherency of iommu access */
 	u8 force_snooping : 1;		/* Create IOPTEs with snoop control */
+	u8 set_pte_snp:1;
 
 	struct list_head devices;	/* all devices' list */
 	struct iova_domain iovad;	/* iova's that belong to this domain */
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 d68f5bbf3e93..98112228ae93 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -2459,7 +2459,7 @@ static int domain_setup_first_level(struct intel_iommu *iommu,
 	if (level == 5)
 		flags |= PASID_FLAG_FL5LP;
 
-	if (domain->domain.type == IOMMU_DOMAIN_UNMANAGED)
+	if (domain->force_snooping)
 		flags |= PASID_FLAG_PAGE_SNOOP;
 
 	return intel_pasid_setup_first_level(iommu, dev, (pgd_t *)pgd, pasid,
@@ -4431,7 +4431,7 @@ static int intel_iommu_map(struct iommu_domain *domain,
 		prot |= DMA_PTE_READ;
 	if (iommu_prot & IOMMU_WRITE)
 		prot |= DMA_PTE_WRITE;
-	if (dmar_domain->force_snooping)
+	if (dmar_domain->set_pte_snp)
 		prot |= DMA_PTE_SNP;
 
 	max_addr = iova + size;
@@ -4554,13 +4554,58 @@ 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);
+	list_for_each_entry(info, &domain->devices, link) {
+		if (!ecap_sc_support(info->iommu->ecap)) {
+			support = false;
+			break;
+		}
+	}
+	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)) {
+		domain->set_pte_snp = true;
+		return;
+	}
+
+	spin_lock_irqsave(&device_domain_lock, flags);
+	list_for_each_entry(info, &domain->devices, link)
+		intel_pasid_setup_page_snoop_control(info->iommu, info->dev,
+						     PASID_RID2PASID);
+	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 (dmar_domain->force_snooping)
+		return true;
+
+	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..41a0e3b02c79 100644
--- a/drivers/iommu/intel/pasid.c
+++ b/drivers/iommu/intel/pasid.c
@@ -762,3 +762,26 @@ 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;
+
+	spin_lock(&iommu->lock);
+	pte = intel_pasid_get_entry(dev, pasid);
+	if (WARN_ON(!pte || !pasid_pte_is_present(pte))) {
+		spin_unlock(&iommu->lock);
+		return;
+	}
+
+	pasid_set_pgsnp(pte);
+	did = pasid_get_domain_id(pte);
+	spin_unlock(&iommu->lock);
+
+	pasid_flush_caches(iommu, pte, pasid, did);
+}
-- 
2.25.1