[Patch v8 10/10] iommu/vt-d: Support reporting nesting capability info

[Liu Yi L <yi.l.liu@intel.com>]

This patch reports nesting info when iommu_domain_get_attr() is called with
DOMAIN_ATTR_NESTING and one domain with nesting set.

Cc: Kevin Tian <kevin.tian@intel.com>
CC: Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Eric Auger <eric.auger@redhat.com>
Cc: Jean-Philippe Brucker <jean-philippe@linaro.org>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
---
v7 -> v8:
*) tweak per latest code base

v6 -> v7:
*) split the patch in v6 into two patches:
   [PATCH v7 15/16] iommu/vt-d: Only support nesting when nesting caps are consistent across iommu units
   [PATCH v7 16/16] iommu/vt-d: Support reporting nesting capability info

v2 -> v3:
*) remove cap/ecap_mask in iommu_nesting_info.
---
 drivers/iommu/intel/cap_audit.h |  7 ++++
 drivers/iommu/intel/iommu.c     | 68 ++++++++++++++++++++++++++++++++-
 2 files changed, 74 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/intel/cap_audit.h b/drivers/iommu/intel/cap_audit.h
index 74cfccae0e81..787e98282a02 100644
--- a/drivers/iommu/intel/cap_audit.h
+++ b/drivers/iommu/intel/cap_audit.h
@@ -60,6 +60,13 @@
 #define ECAP_QI_MASK		BIT_ULL(1)
 #define ECAP_C_MASK		BIT_ULL(0)
 
+/* Capabilities related to nested translation */
+#define VTD_CAP_MASK		(CAP_FL1GP_MASK | CAP_FL5LP_MASK)
+
+#define VTD_ECAP_MASK		(ECAP_PRS_MASK | ECAP_ERS_MASK | \
+				 ECAP_SRS_MASK | ECAP_EAFS_MASK | \
+				 ECAP_PASID_MASK)
+
 /*
  * u64 intel_iommu_cap_sanity, intel_iommu_ecap_sanity will be adjusted as each
  * IOMMU gets audited.
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 4409d86b4e18..f7432fb1c6ea 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -5508,13 +5508,79 @@ static bool domain_use_flush_queue(void)
 	return r;
 }
 
+static int intel_iommu_get_nesting_info(struct iommu_domain *domain,
+					struct iommu_nesting_info *info)
+{
+	struct dmar_domain *dmar_domain = to_dmar_domain(domain);
+	u64 cap = VTD_CAP_MASK, ecap = VTD_ECAP_MASK;
+	struct device_domain_info *domain_info;
+	struct iommu_nesting_info_vtd vtd;
+	unsigned int size;
+
+	if (!info)
+		return -EINVAL;
+
+	if (!(dmar_domain->flags & DOMAIN_FLAG_NESTING_MODE))
+		return -ENODEV;
+
+	size = sizeof(struct iommu_nesting_info);
+	/*
+	 * if provided buffer size is smaller than expected, should
+	 * return 0 and also the expected buffer size to caller.
+	 */
+	if (info->argsz < size) {
+		info->argsz = size;
+		return 0;
+	}
+
+	/*
+	 * arbitrary select the first domain_info as all nesting
+	 * related capabilities should be consistent across iommu
+	 * units.
+	 */
+	domain_info = list_first_entry(&dmar_domain->devices,
+				       struct device_domain_info, link);
+	cap &= domain_info->iommu->cap;
+	ecap &= domain_info->iommu->ecap;
+
+	info->addr_width = dmar_domain->gaw;
+	info->format = IOMMU_PASID_FORMAT_INTEL_VTD;
+	info->features = IOMMU_NESTING_FEAT_BIND_PGTBL |
+			 IOMMU_NESTING_FEAT_CACHE_INVLD;
+	info->pasid_bits = ilog2(intel_pasid_max_id);
+	memset(&info->padding, 0x0, 12);
+
+	vtd.flags = 0;
+	memset(&vtd.padding, 0x0, 12);
+	vtd.cap_reg = cap & VTD_CAP_MASK;
+	vtd.ecap_reg = ecap & VTD_ECAP_MASK;
+
+	memcpy(&info->vendor.vtd, &vtd, sizeof(vtd));
+	return 0;
+}
+
 static int
 intel_iommu_domain_get_attr(struct iommu_domain *domain,
 			    enum iommu_attr attr, void *data)
 {
 	switch (domain->type) {
 	case IOMMU_DOMAIN_UNMANAGED:
-		return -ENODEV;
+		switch (attr) {
+		case DOMAIN_ATTR_NESTING:
+		{
+			struct iommu_nesting_info *info =
+				(struct iommu_nesting_info *)data;
+			unsigned long flags;
+			int ret;
+
+			spin_lock_irqsave(&device_domain_lock, flags);
+			ret = intel_iommu_get_nesting_info(domain, info);
+			spin_unlock_irqrestore(&device_domain_lock, flags);
+			return ret;
+		}
+		default:
+			return -ENODEV;
+		}
 	case IOMMU_DOMAIN_DMA:
 		switch (attr) {
 		case DOMAIN_ATTR_DMA_USE_FLUSH_QUEUE:
-- 
2.25.1