From: Nathan Chen <nathanc@nvidia.com>

Allow accelerated SMMUv3 Address Translation Services support property
to be derived from host IOMMU capabilities. Derive host values using
IOMMU_GET_HW_INFO, retrieving ATS capability from IDR0.

Signed-off-by: Nathan Chen <nathanc@nvidia.com>
---
 hw/arm/smmuv3-accel.c | 10 ++++++++++
 hw/arm/smmuv3.c       |  7 +------
 2 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/hw/arm/smmuv3-accel.c b/hw/arm/smmuv3-accel.c
index a0146c8d31..a835c8f220 100644
--- a/hw/arm/smmuv3-accel.c
+++ b/hw/arm/smmuv3-accel.c
@@ -44,6 +44,12 @@ static void smmuv3_accel_auto_finalise(SMMUv3State *s,
         return;
     }
 
+    /* Update ATS if auto from info */
+    if (s->ats == ON_OFF_AUTO_AUTO) {
+        s->idr[0] = FIELD_DP32(s->idr[0], IDR0, ATS,
+                               FIELD_EX32(info->idr[0], IDR0, ATS));
+    }
+
     accel->auto_finalised = true;
 }
 
@@ -938,4 +944,8 @@ void smmuv3_accel_init(SMMUv3State *s)
     s->s_accel = g_new0(SMMUv3AccelState, 1);
     bs->iommu_ops = &smmuv3_accel_ops;
     smmuv3_accel_as_init(s);
+
+    if (s->ats == ON_OFF_AUTO_AUTO) {
+        s->s_accel->auto_mode = true;
+    }
 }
diff --git a/hw/arm/smmuv3.c b/hw/arm/smmuv3.c
index 09ea08eb18..f3603554e3 100644
--- a/hw/arm/smmuv3.c
+++ b/hw/arm/smmuv3.c
@@ -1973,10 +1973,6 @@ static bool smmu_validate_property(SMMUv3State *s, Error **errp)
     }
 #endif
 
-    if (s->ats == ON_OFF_AUTO_AUTO) {
-        error_setg(errp, "ats auto mode is not supported");
-        return false;
-    }
     if (s->ril == ON_OFF_AUTO_AUTO) {
         error_setg(errp, "ril auto mode is not supported");
         return false;
@@ -2196,8 +2192,7 @@ static void smmuv3_class_init(ObjectClass *klass, const void *data)
         "is not supported.");
     object_class_property_set_description(klass, "ats",
         "Enable/disable ATS support (for accel=on). Please ensure host "
-        "platform has ATS support before enabling this. ats=auto is not "
-        "supported.");
+        "platform has ATS support before enabling this.");
     object_class_property_set_description(klass, "oas",
         "Specify Output Address Size (for accel=on). Supported values "
         "are 44 or 48 bits. Defaults to 44 bits. oas=auto is not "
-- 
2.43.0