* [Qemu-devel] [PATCH v2] spapr: add "stop-self" RTAS call required to support hot CPU unplug
@ 2013-08-28 9:32 Alexey Kardashevskiy
2013-08-28 11:42 ` David Gibson
0 siblings, 1 reply; 4+ messages in thread
From: Alexey Kardashevskiy @ 2013-08-28 9:32 UTC (permalink / raw)
To: qemu-devel
Cc: Alexey Kardashevskiy, Paolo Bonzini, qemu-ppc, Alexander Graf,
David Gibson
PAPR+ requires two RTAS calls to be supported by the hypervisor in
order to allow hotplugging VCPUs from the guest. The "start-cpu" RTAS
call was already there but "stop-self" was not.
This adds the "stop-self" RTAS call.
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
Changes:
v2:
* exit_request flag change replaced with more correct cpu_exit() call
* fixed commit message, "spapr: support CPU hotplug"
---
hw/ppc/spapr_rtas.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
index 394ce05..b906294 100644
--- a/hw/ppc/spapr_rtas.c
+++ b/hw/ppc/spapr_rtas.c
@@ -202,6 +202,17 @@ static void rtas_start_cpu(PowerPCCPU *cpu_, sPAPREnvironment *spapr,
rtas_st(rets, 0, -3);
}
+static void rtas_stop_self(PowerPCCPU *cpu, sPAPREnvironment *spapr,
+ uint32_t token, uint32_t nargs,
+ target_ulong args,
+ uint32_t nret, target_ulong rets)
+{
+ CPUState *cs = CPU(cpu);
+
+ cs->halted = 1;
+ cpu_exit(cs);
+}
+
static struct rtas_call {
const char *name;
spapr_rtas_fn fn;
@@ -322,6 +333,7 @@ static void core_rtas_register_types(void)
spapr_rtas_register("query-cpu-stopped-state",
rtas_query_cpu_stopped_state);
spapr_rtas_register("start-cpu", rtas_start_cpu);
+ spapr_rtas_register("stop-self", rtas_stop_self);
}
type_init(core_rtas_register_types)
--
1.8.4.rc4
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [Qemu-devel] [PATCH v2] spapr: add "stop-self" RTAS call required to support hot CPU unplug
2013-08-28 9:32 [Qemu-devel] [PATCH v2] spapr: add "stop-self" RTAS call required to support hot CPU unplug Alexey Kardashevskiy
@ 2013-08-28 11:42 ` David Gibson
2013-08-29 9:04 ` Alexey Kardashevskiy
0 siblings, 1 reply; 4+ messages in thread
From: David Gibson @ 2013-08-28 11:42 UTC (permalink / raw)
To: Alexey Kardashevskiy; +Cc: Paolo Bonzini, qemu-ppc, qemu-devel, Alexander Graf
[-- Attachment #1: Type: text/plain, Size: 1966 bytes --]
On Wed, Aug 28, 2013 at 07:32:51PM +1000, Alexey Kardashevskiy wrote:
> PAPR+ requires two RTAS calls to be supported by the hypervisor in
> order to allow hotplugging VCPUs from the guest. The "start-cpu" RTAS
> call was already there but "stop-self" was not.
>
> This adds the "stop-self" RTAS call.
>
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> ---
> Changes:
> v2:
> * exit_request flag change replaced with more correct cpu_exit() call
> * fixed commit message, "spapr: support CPU hotplug"
> ---
> hw/ppc/spapr_rtas.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
> index 394ce05..b906294 100644
> --- a/hw/ppc/spapr_rtas.c
> +++ b/hw/ppc/spapr_rtas.c
> @@ -202,6 +202,17 @@ static void rtas_start_cpu(PowerPCCPU *cpu_, sPAPREnvironment *spapr,
> rtas_st(rets, 0, -3);
> }
>
> +static void rtas_stop_self(PowerPCCPU *cpu, sPAPREnvironment *spapr,
> + uint32_t token, uint32_t nargs,
> + target_ulong args,
> + uint32_t nret, target_ulong rets)
> +{
> + CPUState *cs = CPU(cpu);
> +
> + cs->halted = 1;
Uh.. I think you still need the msr = 0, or an interrupt could wake
the cpu up again.
> + cpu_exit(cs);
> +}
> +
> static struct rtas_call {
> const char *name;
> spapr_rtas_fn fn;
> @@ -322,6 +333,7 @@ static void core_rtas_register_types(void)
> spapr_rtas_register("query-cpu-stopped-state",
> rtas_query_cpu_stopped_state);
> spapr_rtas_register("start-cpu", rtas_start_cpu);
> + spapr_rtas_register("stop-self", rtas_stop_self);
> }
>
> type_init(core_rtas_register_types)
--
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
[-- Attachment #2: Type: application/pgp-signature, Size: 836 bytes --]
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [Qemu-devel] [PATCH v2] spapr: add "stop-self" RTAS call required to support hot CPU unplug
2013-08-28 11:42 ` David Gibson
@ 2013-08-29 9:04 ` Alexey Kardashevskiy
2013-08-29 10:11 ` Alexander Graf
0 siblings, 1 reply; 4+ messages in thread
From: Alexey Kardashevskiy @ 2013-08-29 9:04 UTC (permalink / raw)
To: David Gibson
Cc: qemu-devel, Alexander Graf, qemu-ppc, Paolo Bonzini,
Paul Mackerras
On 08/28/2013 09:42 PM, David Gibson wrote:
> On Wed, Aug 28, 2013 at 07:32:51PM +1000, Alexey Kardashevskiy wrote:
>> PAPR+ requires two RTAS calls to be supported by the hypervisor in
>> order to allow hotplugging VCPUs from the guest. The "start-cpu" RTAS
>> call was already there but "stop-self" was not.
>>
>> This adds the "stop-self" RTAS call.
>>
>> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
>> ---
>> Changes:
>> v2:
>> * exit_request flag change replaced with more correct cpu_exit() call
>> * fixed commit message, "spapr: support CPU hotplug"
>> ---
>> hw/ppc/spapr_rtas.c | 12 ++++++++++++
>> 1 file changed, 12 insertions(+)
>>
>> diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
>> index 394ce05..b906294 100644
>> --- a/hw/ppc/spapr_rtas.c
>> +++ b/hw/ppc/spapr_rtas.c
>> @@ -202,6 +202,17 @@ static void rtas_start_cpu(PowerPCCPU *cpu_, sPAPREnvironment *spapr,
>> rtas_st(rets, 0, -3);
>> }
>>
>> +static void rtas_stop_self(PowerPCCPU *cpu, sPAPREnvironment *spapr,
>> + uint32_t token, uint32_t nargs,
>> + target_ulong args,
>> + uint32_t nret, target_ulong rets)
>> +{
>> + CPUState *cs = CPU(cpu);
>> +
>> + cs->halted = 1;
>
> Uh.. I think you still need the msr = 0, or an interrupt could wake
> the cpu up again.
Tried with KVM and TCG - nothing wakes up the stopped CPU :-/
After a CPU stopped, the guest calls H_CPPR and disables interrupts on the
specific CPU (or "server") on the XICS level. And decrementer interrupt
does not wake up the CPU.
What is strange is that with TCG (but not with KVM) I see a warning from
the guest at WARN_ON(get_preferred_offline_state(cpu) !=
CPU_STATE_OFFLINE); (pseries_mach_cpu_die() function) but only when I stop
a CPU (any!) first time in the guest.
Specifically, I can do "echo 0 > ...cpuX/online" and "echo 1 >
...cpuX/online" many times during the same boot but only the first stop at
all generates a warning (the state is 2 which is CPU_STATE_ONLINE).
>> + cpu_exit(cs);
>> +}
>> +
>> static struct rtas_call {
>> const char *name;
>> spapr_rtas_fn fn;
>> @@ -322,6 +333,7 @@ static void core_rtas_register_types(void)
>> spapr_rtas_register("query-cpu-stopped-state",
>> rtas_query_cpu_stopped_state);
>> spapr_rtas_register("start-cpu", rtas_start_cpu);
>> + spapr_rtas_register("stop-self", rtas_stop_self);
>> }
>>
>> type_init(core_rtas_register_types)
>
--
Alexey
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [Qemu-devel] [PATCH v2] spapr: add "stop-self" RTAS call required to support hot CPU unplug
2013-08-29 9:04 ` Alexey Kardashevskiy
@ 2013-08-29 10:11 ` Alexander Graf
0 siblings, 0 replies; 4+ messages in thread
From: Alexander Graf @ 2013-08-29 10:11 UTC (permalink / raw)
To: Alexey Kardashevskiy
Cc: qemu-devel, qemu-ppc, Paolo Bonzini, Paul Mackerras, David Gibson
On 29.08.2013, at 11:04, Alexey Kardashevskiy wrote:
> On 08/28/2013 09:42 PM, David Gibson wrote:
>> On Wed, Aug 28, 2013 at 07:32:51PM +1000, Alexey Kardashevskiy wrote:
>>> PAPR+ requires two RTAS calls to be supported by the hypervisor in
>>> order to allow hotplugging VCPUs from the guest. The "start-cpu" RTAS
>>> call was already there but "stop-self" was not.
>>>
>>> This adds the "stop-self" RTAS call.
>>>
>>> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
>>> ---
>>> Changes:
>>> v2:
>>> * exit_request flag change replaced with more correct cpu_exit() call
>>> * fixed commit message, "spapr: support CPU hotplug"
>>> ---
>>> hw/ppc/spapr_rtas.c | 12 ++++++++++++
>>> 1 file changed, 12 insertions(+)
>>>
>>> diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
>>> index 394ce05..b906294 100644
>>> --- a/hw/ppc/spapr_rtas.c
>>> +++ b/hw/ppc/spapr_rtas.c
>>> @@ -202,6 +202,17 @@ static void rtas_start_cpu(PowerPCCPU *cpu_, sPAPREnvironment *spapr,
>>> rtas_st(rets, 0, -3);
>>> }
>>>
>>> +static void rtas_stop_self(PowerPCCPU *cpu, sPAPREnvironment *spapr,
>>> + uint32_t token, uint32_t nargs,
>>> + target_ulong args,
>>> + uint32_t nret, target_ulong rets)
>>> +{
>>> + CPUState *cs = CPU(cpu);
>>> +
>>> + cs->halted = 1;
>>
>> Uh.. I think you still need the msr = 0, or an interrupt could wake
>> the cpu up again.
>
>
> Tried with KVM and TCG - nothing wakes up the stopped CPU :-/
> After a CPU stopped, the guest calls H_CPPR and disables interrupts on the
> specific CPU (or "server") on the XICS level. And decrementer interrupt
> does not wake up the CPU.
Why not? With TCG it should :).
Alex
^ permalink raw reply [flat|nested] 4+ messages in thread
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2013-08-28 9:32 [Qemu-devel] [PATCH v2] spapr: add "stop-self" RTAS call required to support hot CPU unplug Alexey Kardashevskiy
2013-08-28 11:42 ` David Gibson
2013-08-29 9:04 ` Alexey Kardashevskiy
2013-08-29 10:11 ` Alexander Graf
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