Hi,

On 09/06/2018 03:35 AM, Alex Williamson wrote:
On Thu, 30 Aug 2018 12:09:14 +0800
Lu Baolu <[email protected]> wrote:

Add the response to IOMMU_CAP_AUX_DOMAIN capability query
through iommu_capable(). Return true if IOMMUs support the
scalable mode, return false otherwise.

Cc: Ashok Raj <[email protected]>
Cc: Jacob Pan <[email protected]>
Cc: Kevin Tian <[email protected]>
Cc: Liu Yi L <[email protected]>
Signed-off-by: Lu Baolu <[email protected]>
---
  drivers/iommu/intel-iommu.c | 31 +++++++++++++++++++++++++++++--
  1 file changed, 29 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 3e49d4029058..891ae70e7bf2 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -5193,12 +5193,39 @@ static phys_addr_t intel_iommu_iova_to_phys(struct 
iommu_domain *domain,
        return phys;
  }
+static inline bool scalable_mode_support(void)
+{
+       struct dmar_drhd_unit *drhd;
+       struct intel_iommu *iommu;
+       bool ret = true;
+
+       rcu_read_lock();
+       for_each_active_iommu(iommu, drhd) {
+               if (!sm_supported(iommu)) {
+                       ret = false;
+                       break;
+               }
+       }
+       rcu_read_unlock();
+
+       return ret;
+}
+
  static bool intel_iommu_capable(enum iommu_cap cap)
  {
-       if (cap == IOMMU_CAP_CACHE_COHERENCY)
+       switch (cap) {
+       case IOMMU_CAP_CACHE_COHERENCY:
                return domain_update_iommu_snooping(NULL) == 1;
-       if (cap == IOMMU_CAP_INTR_REMAP)
+       case IOMMU_CAP_INTR_REMAP:
                return irq_remapping_enabled == 1;
+       case IOMMU_CAP_AUX_DOMAIN:
+               return scalable_mode_support();
+       case IOMMU_CAP_NOEXEC:
+       /* PASSTHROUGH */
+       default:
+               pr_info("Unsupported capability query %d\n", cap);
+               break;

Please don't do this, there's no reason to be noisy about a query of a
capability that VT-d doesn't know about.  We implement capabilities
exactly so that relevant drivers can expose a feature and others can
happily (and quietly) ignore them.  Thanks,

Fair enough. I will remove it in the next version.

Best regards,
Lu Baolu
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