[Qemu-devel] [PATCH v0] spapr: Error out when CPU hotplug is attempted on older pseries machines

[Qemu-devel] [PATCH v0] spapr: Error out when CPU hotplug is attempted on older pseries machines

[Bharata B Rao]

CPU hotplug and coldplug aren't supported prior to pseries-2.7.
query-hotpluggable-cpus and coldplug on older pseries machines are crashing
the QEMU. Fix this.

- Let query_hotpluggable_cpus return NULL for pseries < 2.7
- spapr_core_pre_plug() should fail hot/cold plug attempts for pseries < 2.7
- spapr_core_plug() should never be called for pseries < 2.7, hence use
  an assert.

Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
---
Applies on ppc-for-2.7 branch of David's tree.

 hw/ppc/spapr.c          |  5 +++++
 hw/ppc/spapr_cpu_core.c | 19 ++++++-------------
 2 files changed, 11 insertions(+), 13 deletions(-)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 7f33a1b..e3a7912 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -2368,9 +2368,14 @@ static HotpluggableCPUList *spapr_query_hotpluggable_cpus(MachineState *machine)
     int i;
     HotpluggableCPUList *head = NULL;
     sPAPRMachineState *spapr = SPAPR_MACHINE(machine);
+    sPAPRMachineClass *smc = SPAPR_MACHINE_GET_CLASS(machine);
     int spapr_max_cores = max_cpus / smp_threads;
     int smt = kvmppc_smt_threads();
 
+    if (!smc->dr_cpu_enabled) {
+        return NULL;
+    }
+
     for (i = 0; i < spapr_max_cores; i++) {
         HotpluggableCPUList *list_item = g_new0(typeof(*list_item), 1);
         HotpluggableCPU *cpu_item = g_new0(typeof(*cpu_item), 1);
diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c
index 70b6b0b..273207c 100644
--- a/hw/ppc/spapr_cpu_core.c
+++ b/hw/ppc/spapr_cpu_core.c
@@ -162,19 +162,12 @@ void spapr_core_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
     int index;
     int smt = kvmppc_smt_threads();
 
+    g_assert(smc->dr_cpu_enabled);
+
     drc = spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_CPU, cc->core_id);
     index = cc->core_id / smt;
     spapr->cores[index] = OBJECT(dev);
 
-    if (!smc->dr_cpu_enabled) {
-        /*
-         * This is a cold plugged CPU core but the machine doesn't support
-         * DR. So skip the hotplug path ensuring that the core is brought
-         * up online with out an associated DR connector.
-         */
-        return;
-    }
-
     g_assert(drc);
 
     /*
@@ -223,13 +216,13 @@ void spapr_core_pre_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
     char *base_core_type = spapr_get_cpu_core_type(machine->cpu_model);
     const char *type = object_get_typename(OBJECT(dev));
 
-    if (strcmp(base_core_type, type)) {
-        error_setg(&local_err, "CPU core type should be %s", base_core_type);
+    if (!smc->dr_cpu_enabled) {
+        error_setg(&local_err, "CPU hotplug not supported for this machine");
         goto out;
     }
 
-    if (!smc->dr_cpu_enabled && dev->hotplugged) {
-        error_setg(&local_err, "CPU hotplug not supported for this machine");
+    if (strcmp(base_core_type, type)) {
+        error_setg(&local_err, "CPU core type should be %s", base_core_type);
         goto out;
     }
 
-- 
2.7.4

Re: [Qemu-devel] [PATCH v0] spapr: Error out when CPU hotplug is attempted on older pseries machines

[David Gibson]

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On Wed, Jul 06, 2016 at 11:19:30PM +0530, Bharata B Rao wrote:
> CPU hotplug and coldplug aren't supported prior to pseries-2.7.
> query-hotpluggable-cpus and coldplug on older pseries machines are crashing
> the QEMU. Fix this.
> 
> - Let query_hotpluggable_cpus return NULL for pseries < 2.7
> - spapr_core_pre_plug() should fail hot/cold plug attempts for pseries < 2.7
> - spapr_core_plug() should never be called for pseries < 2.7, hence use
>   an assert.
> 
> Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
> ---
> Applies on ppc-for-2.7 branch of David's tree.

Applied to ppc-for-2.7.

> 
>  hw/ppc/spapr.c          |  5 +++++
>  hw/ppc/spapr_cpu_core.c | 19 ++++++-------------
>  2 files changed, 11 insertions(+), 13 deletions(-)
> 
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 7f33a1b..e3a7912 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -2368,9 +2368,14 @@ static HotpluggableCPUList *spapr_query_hotpluggable_cpus(MachineState *machine)
>      int i;
>      HotpluggableCPUList *head = NULL;
>      sPAPRMachineState *spapr = SPAPR_MACHINE(machine);
> +    sPAPRMachineClass *smc = SPAPR_MACHINE_GET_CLASS(machine);
>      int spapr_max_cores = max_cpus / smp_threads;
>      int smt = kvmppc_smt_threads();
>  
> +    if (!smc->dr_cpu_enabled) {
> +        return NULL;
> +    }
> +
>      for (i = 0; i < spapr_max_cores; i++) {
>          HotpluggableCPUList *list_item = g_new0(typeof(*list_item), 1);
>          HotpluggableCPU *cpu_item = g_new0(typeof(*cpu_item), 1);
> diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c
> index 70b6b0b..273207c 100644
> --- a/hw/ppc/spapr_cpu_core.c
> +++ b/hw/ppc/spapr_cpu_core.c
> @@ -162,19 +162,12 @@ void spapr_core_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
>      int index;
>      int smt = kvmppc_smt_threads();
>  
> +    g_assert(smc->dr_cpu_enabled);
> +
>      drc = spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_CPU, cc->core_id);
>      index = cc->core_id / smt;
>      spapr->cores[index] = OBJECT(dev);
>  
> -    if (!smc->dr_cpu_enabled) {
> -        /*
> -         * This is a cold plugged CPU core but the machine doesn't support
> -         * DR. So skip the hotplug path ensuring that the core is brought
> -         * up online with out an associated DR connector.
> -         */
> -        return;
> -    }
> -
>      g_assert(drc);
>  
>      /*
> @@ -223,13 +216,13 @@ void spapr_core_pre_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
>      char *base_core_type = spapr_get_cpu_core_type(machine->cpu_model);
>      const char *type = object_get_typename(OBJECT(dev));
>  
> -    if (strcmp(base_core_type, type)) {
> -        error_setg(&local_err, "CPU core type should be %s", base_core_type);
> +    if (!smc->dr_cpu_enabled) {
> +        error_setg(&local_err, "CPU hotplug not supported for this machine");
>          goto out;
>      }
>  
> -    if (!smc->dr_cpu_enabled && dev->hotplugged) {
> -        error_setg(&local_err, "CPU hotplug not supported for this machine");
> +    if (strcmp(base_core_type, type)) {
> +        error_setg(&local_err, "CPU core type should be %s", base_core_type);
>          goto out;
>      }
>  

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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