[PATCH v2 07/10] xen/physinfo: encode Arm SVE vector length in arch_capabilities

[Luca Fancellu <luca.fancellu@xxxxxxx>]

When the arm platform supports SVE, advertise the feature in the
field arch_capabilities in struct xen_sysctl_physinfo by encoding
the SVE vector length in it.

Signed-off-by: Luca Fancellu <luca.fancellu@xxxxxxx>
---
Changes from v1:
 - Use only arch_capabilities and some defines to encode SVE VL
   (Bertrand, Stefano, Jan)
Changes from RFC:
 - new patch
---
 xen/arch/arm/sysctl.c       | 11 +++++++++++
 xen/include/public/sysctl.h |  3 +++
 2 files changed, 14 insertions(+)

diff --git a/xen/arch/arm/sysctl.c b/xen/arch/arm/sysctl.c
index b0a78a8b10d0..075f52801453 100644
--- a/xen/arch/arm/sysctl.c
+++ b/xen/arch/arm/sysctl.c
@@ -11,11 +11,22 @@
 #include <xen/lib.h>
 #include <xen/errno.h>
 #include <xen/hypercall.h>
+#include <asm/arm64/sve.h>
 #include <public/sysctl.h>
 
 void arch_do_physinfo(struct xen_sysctl_physinfo *pi)
 {
     pi->capabilities |= XEN_SYSCTL_PHYSCAP_hvm | XEN_SYSCTL_PHYSCAP_hap;
+
+    if ( cpu_has_sve )
+    {
+        /* Vector length is divided by 128 to save some space */
+        uint32_t sve_vl = get_sys_vl_len() / SVE_VL_MULTIPLE_VAL;
+
+        sve_vl &= XEN_SYSCTL_PHYSCAP_ARM_SVE_MASK;
+
+        pi->arch_capabilities |= sve_vl << XEN_SYSCTL_PHYSCAP_ARM_SVE_SHFT;
+    }
 }
 
 long arch_do_sysctl(struct xen_sysctl *sysctl,
diff --git a/xen/include/public/sysctl.h b/xen/include/public/sysctl.h
index e8dded9fb94a..ec15d8c5ab47 100644
--- a/xen/include/public/sysctl.h
+++ b/xen/include/public/sysctl.h
@@ -94,6 +94,9 @@ struct xen_sysctl_tbuf_op {
 /* Max XEN_SYSCTL_PHYSCAP_* constant.  Used for ABI checking. */
 #define XEN_SYSCTL_PHYSCAP_MAX XEN_SYSCTL_PHYSCAP_gnttab_v2
 
+#define XEN_SYSCTL_PHYSCAP_ARM_SVE_MASK  (0x1FU)
+#define XEN_SYSCTL_PHYSCAP_ARM_SVE_SHFT  (0)
+
 struct xen_sysctl_physinfo {
     uint32_t threads_per_core;
     uint32_t cores_per_socket;
-- 
2.34.1