[PATCH v5 12/18] iommu/vt-d: Handle reattach of the restored domain

[Samiullah Khawaja]

Reattach the restored domain to the preserved device using restored
domain ID. While reattaching do not setup the context and PASID entries
as those are preserved during liveupdate.

Signed-off-by: Samiullah Khawaja <skhawaja@xxxxxxxxxx>
---
 drivers/iommu/intel/iommu.c      |  32 +++++--
 drivers/iommu/intel/iommu.h      |  14 +++
 drivers/iommu/intel/liveupdate.c | 159 +++++++++++++++++++++++++++++++
 3 files changed, 197 insertions(+), 8 deletions(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index c5044e834337..6d3cbe0745c9 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -2819,6 +2819,9 @@ static int blocking_domain_attach_dev(struct iommu_domain *domain,
 {
 	struct device_domain_info *info = dev_iommu_priv_get(dev);
 
+	if (dev_iommu_restored_state(dev))
+		return -EBUSY;
+
 	iopf_for_domain_remove(info->domain ? &info->domain->domain : NULL, dev);
 	device_block_translation(dev);
 	return 0;
@@ -3187,6 +3190,9 @@ static int intel_iommu_attach_device(struct iommu_domain *domain,
 {
 	int ret;
 
+	if (dev_iommu_restored_state(dev))
+		return intel_iommu_restore_device(domain, dev);
+
 	device_block_translation(dev);
 
 	ret = paging_domain_compatible(domain, dev);
@@ -3317,7 +3323,8 @@ static struct iommu_device *intel_iommu_probe_device(struct device *dev)
 	info->iommu = iommu;
 	RB_CLEAR_NODE(&info->node);
 	if (dev_is_pci(dev)) {
-		if (ecap_dev_iotlb_support(iommu->ecap) &&
+		if (!dev_iommu_restored_state(dev) &&
+		    ecap_dev_iotlb_support(iommu->ecap) &&
 		    pci_ats_supported(pdev) &&
 		    dmar_ats_supported(pdev, iommu)) {
 			info->ats_supported = 1;
@@ -3421,12 +3428,16 @@ static void intel_iommu_release_device(struct device *dev)
 	struct device_domain_info *info = dev_iommu_priv_get(dev);
 	struct intel_iommu *iommu = info->iommu;
 
-	iommu_disable_pci_pri(info);
-	iommu_disable_pci_ats(info);
+	if (!dev_iommu_restored_state(dev)) {
+		iommu_disable_pci_pri(info);
+		iommu_disable_pci_ats(info);
 
-	if (info->pasid_enabled) {
-		pci_disable_pasid(to_pci_dev(dev));
-		info->pasid_enabled = 0;
+		if (info->pasid_enabled) {
+			pci_disable_pasid(to_pci_dev(dev));
+			info->pasid_enabled = 0;
+		}
+	} else {
+		intel_iommu_detach_restored_device(dev);
 	}
 
 	mutex_lock(&iommu->iopf_lock);
@@ -3434,11 +3445,13 @@ static void intel_iommu_release_device(struct device *dev)
 		device_rbtree_remove(info);
 	mutex_unlock(&iommu->iopf_lock);
 
-	if (sm_supported(iommu) && !dev_is_real_dma_subdevice(dev) &&
+	if (!dev_iommu_restored_state(dev) && sm_supported(iommu) &&
+	    !dev_is_real_dma_subdevice(dev) &&
 	    !context_copied(iommu, info->bus, info->devfn))
 		intel_pasid_teardown_sm_context(dev);
 
-	intel_pasid_free_table(dev);
+	if (!dev_iommu_restored_state(dev))
+		intel_pasid_free_table(dev);
 	intel_iommu_debugfs_remove_dev(info);
 	kfree(info);
 }
@@ -3900,6 +3913,9 @@ static int identity_domain_attach_dev(struct iommu_domain *domain,
 	struct intel_iommu *iommu = info->iommu;
 	int ret;
 
+	if (dev_iommu_restored_state(dev))
+		return -EBUSY;
+
 	device_block_translation(dev);
 
 	if (dev_is_real_dma_subdevice(dev))
diff --git a/drivers/iommu/intel/iommu.h b/drivers/iommu/intel/iommu.h
index 3a2cb08c0ac1..25104644317c 100644
--- a/drivers/iommu/intel/iommu.h
+++ b/drivers/iommu/intel/iommu.h
@@ -1310,6 +1310,9 @@ void intel_iommu_unpreserve(struct iommu_device *iommu,
 void clear_unpreserved_context_entries(struct intel_iommu *iommu);
 void intel_iommu_liveupdate_restore_root_table(struct intel_iommu *iommu,
 					       struct iommu_hw_ser *iommu_ser);
+int intel_iommu_restore_device(struct iommu_domain *domain,
+			       struct device *dev);
+int intel_iommu_detach_restored_device(struct device *dev);
 #else
 static inline void clear_unpreserved_context_entries(struct intel_iommu *iommu)
 {
@@ -1319,6 +1322,17 @@ static inline void intel_iommu_liveupdate_restore_root_table(struct intel_iommu
 							     struct iommu_hw_ser *iommu_ser)
 {
 }
+
+static inline int intel_iommu_restore_device(struct iommu_domain *domain,
+					     struct device *dev)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int intel_iommu_detach_restored_device(struct device *dev)
+{
+	return -EOPNOTSUPP;
+}
 #endif
 
 #ifdef CONFIG_INTEL_IOMMU_SVM
diff --git a/drivers/iommu/intel/liveupdate.c b/drivers/iommu/intel/liveupdate.c
index c9e553379683..6e6707eefc8c 100644
--- a/drivers/iommu/intel/liveupdate.c
+++ b/drivers/iommu/intel/liveupdate.c
@@ -351,6 +351,165 @@ void intel_iommu_liveupdate_restore_root_table(struct intel_iommu *iommu,
 	BUG_ON(iommu_for_each_preserved_device(_restore_used_domain_ids, iommu));
 }
 
+static void domain_detach_reattached_iommu(struct dmar_domain *domain,
+					   struct intel_iommu *iommu)
+{
+	struct iommu_domain_info *info;
+
+	guard(mutex)(&iommu->did_lock);
+	info = xa_load(&domain->iommu_array, iommu->seq_id);
+	if (--info->refcnt == 0) {
+		xa_erase(&domain->iommu_array, iommu->seq_id);
+		kfree(info);
+	}
+}
+
+static int domain_reattach_iommu(struct dmar_domain *domain,
+				 struct intel_iommu *iommu,
+				 struct iommu_device_ser *device_ser)
+{
+	struct iommu_domain_info *info, *curr;
+	struct iommu_domain_ser *domain_ser;
+	struct iommu_hw_ser *iommu_hw_ser;
+	int restored_did;
+	int ret;
+
+	if (!iommu_domain_restored_state(&domain->domain))
+		return -EINVAL;
+
+	if (!device_ser->domain_iommu_ser.domain_phys ||
+	    !device_ser->domain_iommu_ser.iommu_phys)
+		return -EINVAL;
+
+	domain_ser = phys_to_virt(device_ser->domain_iommu_ser.domain_phys);
+	if (domain_ser->restored_domain != &domain->domain)
+		return -EINVAL;
+
+	iommu_hw_ser = phys_to_virt(device_ser->domain_iommu_ser.iommu_phys);
+	if (iommu_hw_ser->type != IOMMU_INTEL ||
+	    iommu_hw_ser->intel.phys_addr != iommu->reg_phys)
+		return -EINVAL;
+
+	restored_did = device_ser->domain_iommu_ser.attachment_id;
+	if (!ida_exists(&iommu->domain_ida, restored_did))
+		return -EINVAL;
+
+	info = kzalloc_obj(*info);
+	if (!info)
+		return -ENOMEM;
+
+	guard(mutex)(&iommu->did_lock);
+	curr = xa_load(&domain->iommu_array, iommu->seq_id);
+	if (curr) {
+		curr->refcnt++;
+		kfree(info);
+		return 0;
+	}
+
+	info->refcnt	= 1;
+	info->did	= restored_did;
+	info->iommu	= iommu;
+	curr = xa_cmpxchg(&domain->iommu_array, iommu->seq_id,
+			  NULL, info, GFP_KERNEL);
+	if (curr) {
+		ret = xa_err(curr) ? : -EBUSY;
+		goto err_unlock;
+	}
+
+	return 0;
+
+err_unlock:
+	kfree(info);
+	return ret;
+}
+
+/**
+ * intel_iommu_restore_device() - Restore device domain attachment after live update
+ * @domain: Restored domain
+ * @dev: Restored device
+ *
+ * Return: 0 on success, or negative error code.
+ */
+int intel_iommu_restore_device(struct iommu_domain *domain,
+			       struct device *dev)
+{
+	struct iommu_device_ser *device_ser = dev_iommu_restored_state(dev);
+	struct device_domain_info *info = dev_iommu_priv_get(dev);
+	struct dmar_domain *dmar_domain = to_dmar_domain(domain);
+	struct intel_iommu *iommu = info->iommu;
+	unsigned long flags;
+	int ret;
+
+	if (!device_ser)
+		return -EINVAL;
+
+	if (dev_is_real_dma_subdevice(dev))
+		return -EOPNOTSUPP;
+
+	ret = domain_reattach_iommu(dmar_domain, iommu, device_ser);
+	if (ret)
+		return ret;
+
+	info->domain = dmar_domain;
+	info->domain_attached = true;
+	spin_lock_irqsave(&dmar_domain->lock, flags);
+	list_add(&info->link, &dmar_domain->devices);
+	spin_unlock_irqrestore(&dmar_domain->lock, flags);
+
+	ret = cache_tag_assign_domain(dmar_domain, dev, IOMMU_NO_PASID);
+	if (ret)
+		goto err;
+
+	ret = iopf_for_domain_set(domain, dev);
+	if (ret)
+		goto err;
+
+	return 0;
+
+err:
+	/*
+	 * Detach the restored domain from device and iommu on failure, but keep
+	 * the hardware state intact.
+	 */
+	info->domain_attached = false;
+	cache_tag_unassign_domain(info->domain, dev, IOMMU_NO_PASID);
+	spin_lock_irqsave(&info->domain->lock, flags);
+	list_del(&info->link);
+	spin_unlock_irqrestore(&info->domain->lock, flags);
+
+	domain_detach_reattached_iommu(info->domain, iommu);
+	info->domain = NULL;
+	return ret;
+}
+
+int intel_iommu_detach_restored_device(struct device *dev)
+{
+	struct device_domain_info *info = dev_iommu_priv_get(dev);
+	struct intel_iommu *iommu = info->iommu;
+	struct iommu_domain *domain;
+	unsigned long flags;
+
+	if (!info->domain_attached || !info->domain)
+		return -EINVAL;
+
+	domain = &info->domain->domain;
+	if (!iommu_domain_restored_state(domain))
+		return -EINVAL;
+
+	iopf_for_domain_remove(domain, dev);
+	cache_tag_unassign_domain(info->domain, dev, IOMMU_NO_PASID);
+	info->domain_attached = false;
+
+	spin_lock_irqsave(&info->domain->lock, flags);
+	list_del(&info->link);
+	spin_unlock_irqrestore(&info->domain->lock, flags);
+
+	domain_detach_reattached_iommu(info->domain, iommu);
+	info->domain = NULL;
+
+	return 0;
+}
+
 /**
  * intel_iommu_preserve_device() - Intel IOMMU callback to preserve device state
  * @dev: Target device
-- 
2.55.0.1082.g2b9226bbc0-goog