[PATCH v3 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 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/arm64/sve.c             | 12 ++++++++++++
 xen/arch/arm/include/asm/arm64/sve.h |  2 ++
 xen/arch/arm/sysctl.c                |  3 +++
 xen/include/public/sysctl.h          |  4 ++++
 4 files changed, 21 insertions(+)

diff --git a/xen/arch/arm/arm64/sve.c b/xen/arch/arm/arm64/sve.c
index 6593b59b58e8..409b029e4d21 100644
--- a/xen/arch/arm/arm64/sve.c
+++ b/xen/arch/arm/arm64/sve.c
@@ -117,3 +117,15 @@ void sve_restore_state(struct vcpu *v)
 
     sve_load_ctx(sve_ctx_zreg_end, v->arch.vfp.fpregs, 1);
 }
+
+void sve_arch_cap_physinfo(uint32_t *arch_capabilities)
+{
+    if ( cpu_has_sve )
+    {
+        /* Vector length is divided by 128 to save some space */
+        uint32_t sve_vl = MASK_INSR(domainconfig_encode_vl(get_sys_vl_len()),
+                                    XEN_SYSCTL_PHYSCAP_ARM_SVE_MASK);
+
+        *arch_capabilities |= sve_vl;
+    }
+}
diff --git a/xen/arch/arm/include/asm/arm64/sve.h 
b/xen/arch/arm/include/asm/arm64/sve.h
index 8654b0fac4bc..34b4c39191cb 100644
--- a/xen/arch/arm/include/asm/arm64/sve.h
+++ b/xen/arch/arm/include/asm/arm64/sve.h
@@ -41,6 +41,7 @@ int sve_context_init(struct vcpu *v);
 void sve_context_free(struct vcpu *v);
 void sve_save_state(struct vcpu *v);
 void sve_restore_state(struct vcpu *v);
+void sve_arch_cap_physinfo(uint32_t *arch_capabilities);
 
 #else /* !CONFIG_ARM64_SVE */
 
@@ -69,6 +70,7 @@ static inline int sve_context_init(struct vcpu *v)
 static inline void sve_context_free(struct vcpu *v) {}
 static inline void sve_save_state(struct vcpu *v) {}
 static inline void sve_restore_state(struct vcpu *v) {}
+static inline void sve_arch_cap_physinfo(uint32_t *arch_capabilities) {}
 
 #endif
 
diff --git a/xen/arch/arm/sysctl.c b/xen/arch/arm/sysctl.c
index b0a78a8b10d0..64e4d3e06a6b 100644
--- a/xen/arch/arm/sysctl.c
+++ b/xen/arch/arm/sysctl.c
@@ -11,11 +11,14 @@
 #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;
+
+    sve_arch_cap_physinfo(&pi->arch_capabilities);
 }
 
 long arch_do_sysctl(struct xen_sysctl *sysctl,
diff --git a/xen/include/public/sysctl.h b/xen/include/public/sysctl.h
index e8dded9fb94a..99ea3fa0740b 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
 
+#ifdef __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