[Xen-devel] [PATCH v2 1/2] xen/x86: Convert to hotplug state machine

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

Switch to new CPU hotplug infrastructure.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Suggested-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
---
Changes in v2:
* Replace xen_cpu_up_cancel with xen_cpu_dead
* Use existing CPUHP_AP_ONLINE_DYN instead of introducing new state
* Be more careful with return value of cpuhp_setup_state_nocalls()
  as it may return a positive (non-error) number. (Which suggests
  that comment on top of __cpuhp_setup_state() is probably incorrect)

 arch/x86/xen/enlighten.c   | 115 +++++++++++++++++++++++++--------------------
 include/linux/cpuhotplug.h |   1 +
 2 files changed, 66 insertions(+), 50 deletions(-)

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 78e1d06..e4c3399 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -140,7 +140,9 @@ RESERVE_BRK(shared_info_page_brk, PAGE_SIZE);
 __read_mostly int xen_have_vector_callback;
 EXPORT_SYMBOL_GPL(xen_have_vector_callback);
 
-static struct notifier_block xen_cpu_notifier;
+static int xen_cpu_up_prepare(unsigned int cpu);
+static int xen_cpu_up_online(unsigned int cpu);
+static int xen_cpu_dead(unsigned int cpu);
 
 /*
  * Point at some empty memory to start with. We map the real shared_info
@@ -1541,6 +1543,24 @@ static void __init xen_dom0_set_legacy_features(void)
        x86_platform.legacy.rtc = 1;
 }
 
+static int xen_cpuhp_setup(void)
+{
+       int rc;
+
+       rc = cpuhp_setup_state_nocalls(CPUHP_XEN_PREPARE,
+                                      "XEN_HVM_GUEST_PREPARE",
+                                      xen_cpu_up_prepare, xen_cpu_dead);
+       if (rc >= 0) {
+               rc = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
+                                              "XEN_HVM_GUEST_ONLINE",
+                                              xen_cpu_up_online, NULL);
+               if (rc < 0)
+                       cpuhp_remove_state_nocalls(CPUHP_XEN_PREPARE);
+       }
+
+       return rc >= 0 ? 0 : rc;
+}
+
 /* First C function to be called on Xen boot */
 asmlinkage __visible void __init xen_start_kernel(void)
 {
@@ -1629,7 +1649,7 @@ asmlinkage __visible void __init xen_start_kernel(void)
        xen_initial_gdt = &per_cpu(gdt_page, 0);
 
        xen_smp_init();
-       register_cpu_notifier(&xen_cpu_notifier);
+       WARN_ON(xen_cpuhp_setup());
 
 #ifdef CONFIG_ACPI_NUMA
        /*
@@ -1823,63 +1843,58 @@ static void __init init_hvm_pv_info(void)
        xen_domain_type = XEN_HVM_DOMAIN;
 }
 
-static int xen_cpu_notify(struct notifier_block *self, unsigned long action,
-                        void *hcpu)
+static int xen_cpu_up_prepare(unsigned int cpu)
 {
-       int cpu = (long)hcpu;
        int rc;
 
-       switch (action) {
-       case CPU_UP_PREPARE:
-               if (xen_hvm_domain()) {
-                       /*
-                        * This can happen if CPU was offlined earlier and
-                        * offlining timed out in common_cpu_die().
-                        */
-                       if (cpu_report_state(cpu) == CPU_DEAD_FROZEN) {
-                               xen_smp_intr_free(cpu);
-                               xen_uninit_lock_cpu(cpu);
-                       }
-
-                       if (cpu_acpi_id(cpu) != U32_MAX)
-                               per_cpu(xen_vcpu_id, cpu) = cpu_acpi_id(cpu);
-                       else
-                               per_cpu(xen_vcpu_id, cpu) = cpu;
-                       xen_vcpu_setup(cpu);
+       if (xen_hvm_domain()) {
+               /*
+                * This can happen if CPU was offlined earlier and
+                * offlining timed out in common_cpu_die().
+                */
+               if (cpu_report_state(cpu) == CPU_DEAD_FROZEN) {
+                       xen_smp_intr_free(cpu);
+                       xen_uninit_lock_cpu(cpu);
                }
 
-               if (xen_pv_domain() ||
-                   (xen_have_vector_callback &&
-                    xen_feature(XENFEAT_hvm_safe_pvclock)))
-                       xen_setup_timer(cpu);
+               if (cpu_acpi_id(cpu) != U32_MAX)
+                       per_cpu(xen_vcpu_id, cpu) = cpu_acpi_id(cpu);
+               else
+                       per_cpu(xen_vcpu_id, cpu) = cpu;
+               xen_vcpu_setup(cpu);
+       }
 
-               rc = xen_smp_intr_init(cpu);
-               if (rc) {
-                       WARN(1, "xen_smp_intr_init() for CPU %d failed: %d\n",
-                            cpu, rc);
-                       return NOTIFY_BAD;
-               }
+       if (xen_pv_domain() ||
+           (xen_have_vector_callback &&
+            xen_feature(XENFEAT_hvm_safe_pvclock)))
+               xen_setup_timer(cpu);
 
-               break;
-       case CPU_ONLINE:
-               xen_init_lock_cpu(cpu);
-               break;
-       case CPU_UP_CANCELED:
-               xen_smp_intr_free(cpu);
-               if (xen_pv_domain() ||
-                   (xen_have_vector_callback &&
-                    xen_feature(XENFEAT_hvm_safe_pvclock)))
-                       xen_teardown_timer(cpu);
-               break;
-       default:
-               break;
+       rc = xen_smp_intr_init(cpu);
+       if (rc) {
+               WARN(1, "xen_smp_intr_init() for CPU %d failed: %d\n",
+                    cpu, rc);
+               return rc;
        }
-       return NOTIFY_OK;
+       return 0;
 }
 
-static struct notifier_block xen_cpu_notifier = {
-       .notifier_call  = xen_cpu_notify,
-};
+static int xen_cpu_dead(unsigned int cpu)
+{
+       xen_smp_intr_free(cpu);
+
+       if (xen_pv_domain() ||
+           (xen_have_vector_callback &&
+            xen_feature(XENFEAT_hvm_safe_pvclock)))
+               xen_teardown_timer(cpu);
+
+       return 0;
+}
+
+static int xen_cpu_up_online(unsigned int cpu)
+{
+       xen_init_lock_cpu(cpu);
+       return 0;
+}
 
 #ifdef CONFIG_KEXEC_CORE
 static void xen_hvm_shutdown(void)
@@ -1910,7 +1925,7 @@ static void __init xen_hvm_guest_init(void)
        if (xen_feature(XENFEAT_hvm_callback_vector))
                xen_have_vector_callback = 1;
        xen_hvm_smp_init();
-       register_cpu_notifier(&xen_cpu_notifier);
+       WARN_ON(xen_cpuhp_setup());
        xen_unplug_emulated_devices();
        x86_init.irqs.intr_init = xen_init_IRQ;
        xen_hvm_init_time_ops();
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 242bf53..33d352f 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -21,6 +21,7 @@ enum cpuhp_state {
        CPUHP_X2APIC_PREPARE,
        CPUHP_SMPCFD_PREPARE,
        CPUHP_RCUTREE_PREP,
+       CPUHP_XEN_PREPARE,
        CPUHP_NOTIFY_PREPARE,
        CPUHP_TIMERS_DEAD,
        CPUHP_BRINGUP_CPU,
-- 
2.7.4


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
https://lists.xen.org/xen-devel