This patch reports nesting info, and only supports the case where all
the physical iomms have the same CAP/ECAP MASKS.

Cc: Kevin Tian <kevin.t...@intel.com>
CC: Jacob Pan <jacob.jun....@linux.intel.com>
Cc: Alex Williamson <alex.william...@redhat.com>
Cc: Eric Auger <eric.au...@redhat.com>
Cc: Jean-Philippe Brucker <jean-phili...@linaro.org>
Cc: Joerg Roedel <j...@8bytes.org>
Cc: Lu Baolu <baolu...@linux.intel.com>
Signed-off-by: Liu Yi L <yi.l....@intel.com>
Signed-off-by: Jacob Pan <jacob.jun....@linux.intel.com>
---
v2 -> v3:
*) remove cap/ecap_mask in iommu_nesting_info.
---
 drivers/iommu/intel/iommu.c | 81 +++++++++++++++++++++++++++++++++++++++++++--
 include/linux/intel-iommu.h | 16 +++++++++
 2 files changed, 95 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 88f4647..0835804 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -5660,12 +5660,16 @@ static inline bool iommu_pasid_support(void)
 static inline bool nested_mode_support(void)
 {
        struct dmar_drhd_unit *drhd;
-       struct intel_iommu *iommu;
+       struct intel_iommu *iommu, *prev = NULL;
        bool ret = true;
 
        rcu_read_lock();
        for_each_active_iommu(iommu, drhd) {
-               if (!sm_supported(iommu) || !ecap_nest(iommu->ecap)) {
+               if (!prev)
+                       prev = iommu;
+               if (!sm_supported(iommu) || !ecap_nest(iommu->ecap) ||
+                   (VTD_CAP_MASK & (iommu->cap ^ prev->cap)) ||
+                   (VTD_ECAP_MASK & (iommu->ecap ^ prev->ecap))) {
                        ret = false;
                        break;
                }
@@ -6081,6 +6085,78 @@ intel_iommu_domain_set_attr(struct iommu_domain *domain,
        return ret;
 }
 
+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 long flags;
+       unsigned int size;
+
+       if (domain->type != IOMMU_DOMAIN_UNMANAGED ||
+           !(dmar_domain->flags & DOMAIN_FLAG_NESTING_MODE))
+               return -ENODEV;
+
+       if (!info)
+               return -EINVAL;
+
+       size = sizeof(struct iommu_nesting_info) +
+               sizeof(struct iommu_nesting_info_vtd);
+       /*
+        * 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;
+       }
+
+       spin_lock_irqsave(&device_domain_lock, flags);
+       /*
+        * 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;
+       spin_unlock_irqrestore(&device_domain_lock, flags);
+
+       info->format = IOMMU_PASID_FORMAT_INTEL_VTD;
+       info->features = IOMMU_NESTING_FEAT_SYSWIDE_PASID |
+                        IOMMU_NESTING_FEAT_BIND_PGTBL |
+                        IOMMU_NESTING_FEAT_CACHE_INVLD;
+       info->addr_width = dmar_domain->gaw;
+       info->pasid_bits = ilog2(intel_pasid_max_id);
+       info->padding = 0;
+       vtd.flags = 0;
+       vtd.padding = 0;
+       vtd.cap_reg = cap;
+       vtd.ecap_reg = ecap;
+
+       memcpy(info->data, &vtd, sizeof(vtd));
+       return 0;
+}
+
+static int intel_iommu_domain_get_attr(struct iommu_domain *domain,
+                                      enum iommu_attr attr, void *data)
+{
+       switch (attr) {
+       case DOMAIN_ATTR_NESTING:
+       {
+               struct iommu_nesting_info *info =
+                               (struct iommu_nesting_info *)data;
+
+               return intel_iommu_get_nesting_info(domain, info);
+       }
+       default:
+               return -ENOENT;
+       }
+}
+
 /*
  * Check that the device does not live on an external facing PCI port that is
  * marked as untrusted. Such devices should not be able to apply quirks and
@@ -6103,6 +6179,7 @@ const struct iommu_ops intel_iommu_ops = {
        .domain_alloc           = intel_iommu_domain_alloc,
        .domain_free            = intel_iommu_domain_free,
        .domain_set_attr        = intel_iommu_domain_set_attr,
+       .domain_get_attr        = intel_iommu_domain_get_attr,
        .attach_dev             = intel_iommu_attach_device,
        .detach_dev             = intel_iommu_detach_device,
        .aux_attach_dev         = intel_iommu_aux_attach_device,
diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
index f98146b..5acf795 100644
--- a/include/linux/intel-iommu.h
+++ b/include/linux/intel-iommu.h
@@ -197,6 +197,22 @@
 #define ecap_max_handle_mask(e) ((e >> 20) & 0xf)
 #define ecap_sc_support(e)     ((e >> 7) & 0x1) /* Snooping Control */
 
+/* Nesting Support Capability Alignment */
+#define VTD_CAP_FL1GP          BIT_ULL(56)
+#define VTD_CAP_FL5LP          BIT_ULL(60)
+#define VTD_ECAP_PRS           BIT_ULL(29)
+#define VTD_ECAP_ERS           BIT_ULL(30)
+#define VTD_ECAP_SRS           BIT_ULL(31)
+#define VTD_ECAP_EAFS          BIT_ULL(34)
+#define VTD_ECAP_PASID         BIT_ULL(40)
+
+/* Only capabilities marked in below MASKs are reported */
+#define VTD_CAP_MASK           (VTD_CAP_FL1GP | VTD_CAP_FL5LP)
+
+#define VTD_ECAP_MASK          (VTD_ECAP_PRS | VTD_ECAP_ERS | \
+                                VTD_ECAP_SRS | VTD_ECAP_EAFS | \
+                                VTD_ECAP_PASID)
+
 /* Virtual command interface capability */
 #define vccap_pasid(v)         (((v) & DMA_VCS_PAS)) /* PASID allocation */
 
-- 
2.7.4

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