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Subject[PATCH 1/2] xen/x86: Convert to hotplug state machine
Date
Switch to new CPU hotplug infrastructure.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Suggested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
arch/x86/xen/enlighten.c | 115 +++++++++++++++++++++++++-------------------
include/linux/cpuhotplug.h | 2 +
2 files changed, 67 insertions(+), 50 deletions(-)

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index c7f6b1f..2283976 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_up_cancel(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_up_cancel);
+ if (!rc) {
+ rc = cpuhp_setup_state_nocalls(CPUHP_AP_XEN_ONLINE,
+ "XEN_HVM_GUEST_PREPARE",
+ xen_cpu_up_online, NULL);
+ if (rc)
+ cpuhp_remove_state_nocalls(CPUHP_XEN_PREPARE);
+ }
+
+ return 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_up_cancel(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..d6beeb9 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,
@@ -93,6 +94,7 @@ enum cpuhp_state {
CPUHP_AP_ONLINE_DYN_END = CPUHP_AP_ONLINE_DYN + 30,
CPUHP_AP_X86_HPET_ONLINE,
CPUHP_AP_X86_KVM_CLK_ONLINE,
+ CPUHP_AP_XEN_ONLINE,
CPUHP_AP_ACTIVE,
CPUHP_ONLINE,
};
--
1.7.1
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