[PATCH] iommu/vt-d: Refactor PCI PRI enabling/disabling callbacks

[Lu Baolu]

Commit 0095bf83554f8 ("iommu: Improve iopf_queue_remove_device()")
specified the flow for disabling the PRI on a device. Refactor the
PRI callbacks in the intel iommu driver to better manage PRI
enabling and disabling and align it with the device queue interfaces
in the iommu core.

Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
---
 drivers/iommu/intel/iommu.h |  9 +++++
 drivers/iommu/intel/iommu.c | 77 ++++++++++++++++++++++++++++++++++---
 drivers/iommu/intel/pasid.c |  2 -
 3 files changed, 81 insertions(+), 7 deletions(-)

diff --git a/drivers/iommu/intel/iommu.h b/drivers/iommu/intel/iommu.h
index eaf015b4353b..3d5d8f786906 100644
--- a/drivers/iommu/intel/iommu.h
+++ b/drivers/iommu/intel/iommu.h
@@ -1047,6 +1047,15 @@ static inline void context_set_sm_pre(struct context_entry *context)
 	context->lo |= BIT_ULL(4);
 }
 
+/*
+ * Clear the PRE(Page Request Enable) field of a scalable mode context
+ * entry.
+ */
+static inline void context_clear_sm_pre(struct context_entry *context)
+{
+	context->lo &= ~BIT_ULL(4);
+}
+
 /* Returns a number of VTD pages, but aligned to MM page size */
 static inline unsigned long aligned_nrpages(unsigned long host_addr, size_t size)
 {
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 2e9811bf2a4e..2d4b122bcc1c 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -4213,6 +4213,57 @@ static int intel_iommu_enable_sva(struct device *dev)
 	return 0;
 }
 
+/*
+ * Invalidate the caches for a present-to-present change in a context
+ * table entry according to the Spec 6.5.3.3 (Guidance to Software for
+ * Invalidations).
+ *
+ * Since context entry is not encoded by domain-id when operating in
+ * scalable-mode (refer Section 6.2.1), this performs coarser
+ * invalidation than the domain-selective granularity requested.
+ */
+static void invalidate_present_context_change(struct device_domain_info *info)
+{
+	struct intel_iommu *iommu = info->iommu;
+
+	iommu->flush.flush_context(iommu, 0, 0, 0, DMA_CCMD_GLOBAL_INVL);
+	if (sm_supported(iommu))
+		qi_flush_pasid_cache(iommu, 0, QI_PC_GLOBAL, 0);
+	iommu->flush.flush_iotlb(iommu, 0, 0, 0, DMA_TLB_GLOBAL_FLUSH);
+	__iommu_flush_dev_iotlb(info, 0, MAX_AGAW_PFN_WIDTH);
+}
+
+static int context_flip_pri(struct device_domain_info *info, bool enable)
+{
+	struct intel_iommu *iommu = info->iommu;
+	u8 bus = info->bus, devfn = info->devfn;
+	struct context_entry *context;
+
+	spin_lock(&iommu->lock);
+	if (context_copied(iommu, bus, devfn)) {
+		spin_unlock(&iommu->lock);
+		return -EINVAL;
+	}
+
+	context = iommu_context_addr(iommu, bus, devfn, false);
+	if (!context || !context_present(context)) {
+		spin_unlock(&iommu->lock);
+		return -ENODEV;
+	}
+
+	if (enable)
+		context_set_sm_pre(context);
+	else
+		context_clear_sm_pre(context);
+
+	if (!ecap_coherent(iommu->ecap))
+		clflush_cache_range(context, sizeof(*context));
+	invalidate_present_context_change(info);
+	spin_unlock(&iommu->lock);
+
+	return 0;
+}
+
 static int intel_iommu_enable_iopf(struct device *dev)
 {
 	struct pci_dev *pdev = dev_is_pci(dev) ? to_pci_dev(dev) : NULL;
@@ -4242,15 +4293,23 @@ static int intel_iommu_enable_iopf(struct device *dev)
 	if (ret)
 		return ret;
 
+	ret = context_flip_pri(info, true);
+	if (ret)
+		goto err_remove_device;
+
 	ret = pci_enable_pri(pdev, PRQ_DEPTH);
-	if (ret) {
-		iopf_queue_remove_device(iommu->iopf_queue, dev);
-		return ret;
-	}
+	if (ret)
+		goto err_clear_pri;
 
 	info->pri_enabled = 1;
 
 	return 0;
+err_clear_pri:
+	context_flip_pri(info, false);
+err_remove_device:
+	iopf_queue_remove_device(iommu->iopf_queue, dev);
+
+	return ret;
 }
 
 static int intel_iommu_disable_iopf(struct device *dev)
@@ -4261,6 +4320,15 @@ static int intel_iommu_disable_iopf(struct device *dev)
 	if (!info->pri_enabled)
 		return -EINVAL;
 
+	/* Disable new PRI reception: */
+	context_flip_pri(info, false);
+
+	/*
+	 * Remove device from fault queue and acknowledge all outstanding
+	 * PRQs to the device:
+	 */
+	iopf_queue_remove_device(iommu->iopf_queue, dev);
+
 	/*
 	 * PCIe spec states that by clearing PRI enable bit, the Page
 	 * Request Interface will not issue new page requests, but has
@@ -4271,7 +4339,6 @@ static int intel_iommu_disable_iopf(struct device *dev)
 	 */
 	pci_disable_pri(to_pci_dev(dev));
 	info->pri_enabled = 0;
-	iopf_queue_remove_device(iommu->iopf_queue, dev);
 
 	return 0;
 }
diff --git a/drivers/iommu/intel/pasid.c b/drivers/iommu/intel/pasid.c
index abce19e2ad6f..286a8a7d66f5 100644
--- a/drivers/iommu/intel/pasid.c
+++ b/drivers/iommu/intel/pasid.c
@@ -768,8 +768,6 @@ static int context_entry_set_pasid_table(struct context_entry *context,
 
 	if (info->ats_supported)
 		context_set_sm_dte(context);
-	if (info->pri_supported)
-		context_set_sm_pre(context);
 	if (info->pasid_supported)
 		context_set_pasid(context);
 
-- 
2.34.1