[PATCH v6 08/12] 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>
Reviewed-by: Bertrand Marquis <bertrand.marquis@xxxxxxx>
---
Changes from v5:
 - Add R-by from Bertrand
Changes from v4:
 - Write arch_capabilities from arch_do_physinfo instead of using
   stub functions (Jan)
Changes from v3:
 - domainconfig_encode_vl is now named sve_encode_vl
Changes from v2:
 - Remove XEN_SYSCTL_PHYSCAP_ARM_SVE_SHFT, use MASK_INSR and
   protect with ifdef XEN_SYSCTL_PHYSCAP_ARM_SVE_MASK (Jan)
 - Use the helper function sve_arch_cap_physinfo to encode
   the VL into physinfo arch_capabilities field.
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       | 4 ++++
 xen/include/public/sysctl.h | 4 ++++
 2 files changed, 8 insertions(+)

diff --git a/xen/arch/arm/sysctl.c b/xen/arch/arm/sysctl.c
index b0a78a8b10d0..e9a0661146e4 100644
--- a/xen/arch/arm/sysctl.c
+++ b/xen/arch/arm/sysctl.c
@@ -11,11 +11,15 @@
 #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;
+
+    pi->arch_capabilities |= MASK_INSR(sve_encode_vl(get_sys_vl_len()),
+                                       XEN_SYSCTL_PHYSCAP_ARM_SVE_MASK);
 }
 
 long arch_do_sysctl(struct xen_sysctl *sysctl,
diff --git a/xen/include/public/sysctl.h b/xen/include/public/sysctl.h
index 2b24d6bfd00e..9d06e92d0f6a 100644
--- a/xen/include/public/sysctl.h
+++ b/xen/include/public/sysctl.h
@@ -94,6 +94,10 @@ struct xen_sysctl_tbuf_op {
 /* Max XEN_SYSCTL_PHYSCAP_* constant.  Used for ABI checking. */
 #define XEN_SYSCTL_PHYSCAP_MAX XEN_SYSCTL_PHYSCAP_gnttab_v2
 
+#if defined(__arm__) || defined(__aarch64__)
+#define XEN_SYSCTL_PHYSCAP_ARM_SVE_MASK  (0x1FU)
+#endif
+
 struct xen_sysctl_physinfo {
     uint32_t threads_per_core;
     uint32_t cores_per_socket;
-- 
2.34.1