[PATCH 07/10] xen/physinfo: add arm SVE arch capability and vector length

[Luca Fancellu <luca.fancellu@xxxxxxx>]

When the arm platform supports SVE, advertise the feature by a new
flag for the arch_capabilities in struct xen_sysctl_physinfo and add
a new field "arm_sve_vl_bits" where on arm there can be stored the
maximum SVE vector length in bits.

Update the padding.

Bump XEN_SYSCTL_INTERFACE_VERSION for the changes.

Signed-off-by: Luca Fancellu <luca.fancellu@xxxxxxx>
---
Changes from RFC:
 - new patch
---
Here I need an opinion from arm and x86 maintainer, I see there is no arch
specific structure in struct xen_sysctl_physinfo, hw_cap is used only by x86
and now arch_capabilities and the new arm_sve_vl_bits will be used only by arm.
So how should we proceed here? Shall we create a struct arch for each
architecture and for example move arch_capabilities inside it (renaming to
capabilities) and every arch specific field as well?
(is hw_cap only for x86?)
---
 xen/arch/arm/sysctl.c       |  7 +++++++
 xen/include/public/sysctl.h | 11 +++++++++--
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/xen/arch/arm/sysctl.c b/xen/arch/arm/sysctl.c
index b0a78a8b10d0..d65f8be498f4 100644
--- a/xen/arch/arm/sysctl.c
+++ b/xen/arch/arm/sysctl.c
@@ -11,11 +11,18 @@
 #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 )
+    {
+        pi->arch_capabilities |= XEN_SYSCTL_PHYSCAP_ARM_sve;
+        pi->arm_sve_vl_bits = get_sys_vl_len();
+    }
 }
 
 long arch_do_sysctl(struct xen_sysctl *sysctl,
diff --git a/xen/include/public/sysctl.h b/xen/include/public/sysctl.h
index 001a4de27375..5acbb41256bc 100644
--- a/xen/include/public/sysctl.h
+++ b/xen/include/public/sysctl.h
@@ -18,7 +18,7 @@
 #include "domctl.h"
 #include "physdev.h"
 
-#define XEN_SYSCTL_INTERFACE_VERSION 0x00000015
+#define XEN_SYSCTL_INTERFACE_VERSION 0x00000016
 
 /*
  * Read console content from Xen buffer ring.
@@ -94,6 +94,12 @@ struct xen_sysctl_tbuf_op {
 /* Max XEN_SYSCTL_PHYSCAP_* constant.  Used for ABI checking. */
 #define XEN_SYSCTL_PHYSCAP_MAX XEN_SYSCTL_PHYSCAP_gnttab_v2
 
+/* Arm platform is SVE capable */
+#define XEN_SYSCTL_PHYSCAP_ARM_sve (1u << 0)
+
+/* Max XEN_SYSCTL_PHYSCAP_ARM_* constant.  Used for ABI checking. */
+#define XEN_SYSCTL_PHYSCAP_ARM_MAX XEN_SYSCTL_PHYSCAP_ARM_sve
+
 struct xen_sysctl_physinfo {
     uint32_t threads_per_core;
     uint32_t cores_per_socket;
@@ -104,7 +110,8 @@ struct xen_sysctl_physinfo {
     uint32_t cpu_khz;
     uint32_t capabilities;/* XEN_SYSCTL_PHYSCAP_??? */
     uint32_t arch_capabilities;/* XEN_SYSCTL_PHYSCAP_{X86,ARM,...}_??? */
-    uint32_t pad;
+    uint16_t arm_sve_vl_bits;
+    uint16_t pad;
     uint64_aligned_t total_pages;
     uint64_aligned_t free_pages;
     uint64_aligned_t scrub_pages;
-- 
2.25.1