[PATCH v1 3/4] arm/sysctl: Implement cpu hotplug ops

[Mykyta Poturai <Mykyta_Poturai@xxxxxxxx>]

Implement XEN_SYSCTL_CPU_HOTPLUG_* calls to allow for enabling/disabling
CPU cores in runtime.

Signed-off-by: Mykyta Poturai <mykyta_poturai@xxxxxxxx>
---
 xen/arch/arm/sysctl.c | 67 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 67 insertions(+)

diff --git a/xen/arch/arm/sysctl.c b/xen/arch/arm/sysctl.c
index 32cab4feff..ca8fb550fd 100644
--- a/xen/arch/arm/sysctl.c
+++ b/xen/arch/arm/sysctl.c
@@ -12,6 +12,7 @@
 #include <xen/dt-overlay.h>
 #include <xen/errno.h>
 #include <xen/hypercall.h>
+#include <xen/cpu.h>
 #include <asm/arm64/sve.h>
 #include <public/sysctl.h>
 
@@ -23,6 +24,68 @@ void arch_do_physinfo(struct xen_sysctl_physinfo *pi)
                                        XEN_SYSCTL_PHYSCAP_ARM_SVE_MASK);
 }
 
+static long cpu_up_helper(void *data)
+{
+    unsigned long cpu = (unsigned long) data;
+    return cpu_up(cpu);
+}
+
+static long cpu_down_helper(void *data)
+{
+    unsigned long cpu = (unsigned long) data;
+    return cpu_down(cpu);
+}
+
+static long smt_up_down_helper(void *data)
+{
+    bool up = (bool) data;
+    unsigned int cpu;
+    int ret;
+
+    for_each_present_cpu ( cpu )
+    {
+        if ( cpu == 0 )
+            continue;
+
+        if ( up )
+            ret = cpu_up(cpu);
+        else
+            ret = cpu_down(cpu);
+
+        if ( ret )
+            return ret;
+    }
+
+    return 0;
+}
+
+static long cpu_hotplug_sysctl(struct xen_sysctl_cpu_hotplug *hotplug)
+{
+    bool up;
+
+    switch (hotplug->op) {
+        case XEN_SYSCTL_CPU_HOTPLUG_ONLINE:
+            if ( hotplug->cpu == 0 )
+                return -EINVAL;
+            return continue_hypercall_on_cpu(0, cpu_up_helper, 
_p(hotplug->cpu));
+
+        case XEN_SYSCTL_CPU_HOTPLUG_OFFLINE:
+            if ( hotplug->cpu == 0 )
+                return -EINVAL;
+            return continue_hypercall_on_cpu(0, cpu_down_helper, 
_p(hotplug->cpu));
+
+        case XEN_SYSCTL_CPU_HOTPLUG_SMT_ENABLE:
+        case XEN_SYSCTL_CPU_HOTPLUG_SMT_DISABLE:
+            if ( CONFIG_NR_CPUS <= 1 )
+                return 0;
+            up = hotplug->op == XEN_SYSCTL_CPU_HOTPLUG_SMT_ENABLE;
+            return continue_hypercall_on_cpu(0, smt_up_down_helper, _p(up));
+
+        default:
+            return -EINVAL;
+    }
+}
+
 long arch_do_sysctl(struct xen_sysctl *sysctl,
                     XEN_GUEST_HANDLE_PARAM(xen_sysctl_t) u_sysctl)
 {
@@ -34,6 +97,10 @@ long arch_do_sysctl(struct xen_sysctl *sysctl,
         ret = dt_overlay_sysctl(&sysctl->u.dt_overlay);
         break;
 
+    case XEN_SYSCTL_cpu_hotplug:
+        ret = cpu_hotplug_sysctl(&sysctl->u.cpu_hotplug);
+        break;
+
     default:
         ret = -ENOSYS;
         break;
-- 
2.34.1