[RFC PATCH 8/8] xen/arm: add sve property for dom0less domUs

[Luca Fancellu <luca.fancellu@xxxxxxx>]

Add a device tree property in the dom0less domU configuration
to enable the guest to use SVE.

Update documentation.

Signed-off-by: Luca Fancellu <luca.fancellu@xxxxxxx>
---
 docs/misc/arm/device-tree/booting.txt | 7 +++++++
 xen/arch/arm/domain_build.c           | 7 +++++++
 2 files changed, 14 insertions(+)

diff --git a/docs/misc/arm/device-tree/booting.txt 
b/docs/misc/arm/device-tree/booting.txt
index 3879340b5e0a..3d1ce652317e 100644
--- a/docs/misc/arm/device-tree/booting.txt
+++ b/docs/misc/arm/device-tree/booting.txt
@@ -193,6 +193,13 @@ with the following properties:
     Optional. Handle to a xen,cpupool device tree node that identifies the
     cpupool where the guest will be started at boot.
 
+- sve
+
+    Optional. A number that, when above 0, enables SVE for this guest and sets
+    its maximum SVE vector length. The default value is 0, that means this
+    guest is not allowed to use SVE, the maximum value allowed is 2048, any
+    other value must be multiple of 128.
+
 - xen,enhanced
 
     A string property. Possible property values are:
diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index 48c3fdc28063..05b2bfc9195f 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -3959,6 +3959,13 @@ void __init create_domUs(void)
             d_cfg.max_maptrack_frames = val;
         }
 
+        if ( dt_property_read_u32(node, "sve", &val) )
+        {
+            if ( val > UINT16_MAX )
+                panic("sve property value (%"PRIu32") overflow\n", val);
+            d_cfg.arch.sve_vl_bits = val;
+        }
+
         /*
          * The variable max_init_domid is initialized with zero, so here it's
          * very important to use the pre-increment operator to call
-- 
2.17.1