* [PATCH for-6.1 v5 0/1] machine: Disallow specifying topology parameters as zero
@ 2021-07-23 9:57 Yanan Wang
2021-07-23 9:57 ` [PATCH for-6.1 v5 1/1] " Yanan Wang
0 siblings, 1 reply; 3+ messages in thread
From: Yanan Wang @ 2021-07-23 9:57 UTC (permalink / raw)
To: qemu-devel
Cc: Peter Maydell, Andrew Jones, Daniel P . Berrangé,
Eduardo Habkost, Pierre Morel, Pankaj Gupta, wanghaibin.wang,
Cornelia Huck, Markus Armbruster, Yanan Wang, Cleber Rosa,
yuzenghui, Paolo Bonzini
In the SMP configuration, we should either specify a topology
parameter with a reasonable value (equal to or greater than 1)
or just leave it omitted and QEMU will calculate its value.
Configurations which explicitly specify the topology parameters
as zero like "sockets=0" are meaningless, so disallow them.
However; the commit 1e63fe685804d
(machine: pass QAPI struct to mc->smp_parse) has documented that
'0' has the same semantics as omitting a parameter in the qapi
comment for SMPConfiguration. So this patch fixes the doc and
also adds the corresponding sanity check.
This patch originly comes form [1], and it was suggested that
this patch fixing the doc should be sent for 6.1 to avoid a
deprecation process in the future.
[1] https://lore.kernel.org/qemu-devel/YPWsThPiZa3mF+zp@redhat.com/
v4->v5:
- tweak the error message (Markus)
- v4: https://lore.kernel.org/qemu-devel/20210723073122.7720-1-wangyanan55@huawei.com/
v3->v4:
- fix the typos
- v3: https://lore.kernel.org/qemu-devel/20210723020002.18456-1-wangyanan55@huawei.com/
v2->v3:
- improve the error message
- v2: https://lore.kernel.org/qemu-devel/20210722154326.1464-1-wangyanan55@huawei.com/
v1->v2:
- move the check to machine_set_smp
- update qemu-option.hx
- v1: https://lore.kernel.org/qemu-devel/20210722021512.2600-1-wangyanan55@huawei.com/
Yanan Wang (1):
machine: Disallow specifying topology parameters as zero
hw/core/machine.c | 14 ++++++++++++++
qapi/machine.json | 6 +++---
qemu-options.hx | 12 +++++++-----
3 files changed, 24 insertions(+), 8 deletions(-)
--
2.19.1
^ permalink raw reply [flat|nested] 3+ messages in thread
* [PATCH for-6.1 v5 1/1] machine: Disallow specifying topology parameters as zero
2021-07-23 9:57 [PATCH for-6.1 v5 0/1] machine: Disallow specifying topology parameters as zero Yanan Wang
@ 2021-07-23 9:57 ` Yanan Wang
2021-08-06 8:27 ` wangyanan (Y)
0 siblings, 1 reply; 3+ messages in thread
From: Yanan Wang @ 2021-07-23 9:57 UTC (permalink / raw)
To: qemu-devel
Cc: Peter Maydell, Andrew Jones, Daniel P . Berrangé,
Eduardo Habkost, Pierre Morel, Pankaj Gupta, wanghaibin.wang,
Cornelia Huck, Markus Armbruster, Yanan Wang, Cleber Rosa,
yuzenghui, Paolo Bonzini
In the SMP configuration, we should either specify a topology
parameter with a reasonable value (equal to or greater than 1)
or just leave it omitted and QEMU will calculate its value.
Configurations which explicitly specify the topology parameters
as zero like "sockets=0" are meaningless, so disallow them.
However, the commit 1e63fe685804d
(machine: pass QAPI struct to mc->smp_parse) has documented that
'0' has the same semantics as omitting a parameter in the qapi
comment for SMPConfiguration. So this patch fixes the doc and
also adds the corresponding sanity check.
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Tested-by: Daniel P. Berrange <berrange@redhat.com>
Suggested-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
---
hw/core/machine.c | 14 ++++++++++++++
qapi/machine.json | 6 +++---
qemu-options.hx | 12 +++++++-----
3 files changed, 24 insertions(+), 8 deletions(-)
diff --git a/hw/core/machine.c b/hw/core/machine.c
index 775add0795..e1533dfc47 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -829,6 +829,20 @@ static void machine_set_smp(Object *obj, Visitor *v, const char *name,
return;
}
+ /*
+ * The CPU topology parameters must be specified greater than zero or
+ * just omitted, explicit configuration like "cpus=0" is not allowed.
+ */
+ if ((config->has_cpus && config->cpus == 0) ||
+ (config->has_sockets && config->sockets == 0) ||
+ (config->has_dies && config->dies == 0) ||
+ (config->has_cores && config->cores == 0) ||
+ (config->has_threads && config->threads == 0) ||
+ (config->has_maxcpus && config->maxcpus == 0)) {
+ error_setg(errp, "CPU topology parameters must be greater than zero");
+ goto out_free;
+ }
+
mc->smp_parse(ms, config, errp);
if (errp) {
goto out_free;
diff --git a/qapi/machine.json b/qapi/machine.json
index c3210ee1fb..9272cb3cf8 100644
--- a/qapi/machine.json
+++ b/qapi/machine.json
@@ -1288,8 +1288,8 @@
##
# @SMPConfiguration:
#
-# Schema for CPU topology configuration. "0" or a missing value lets
-# QEMU figure out a suitable value based on the ones that are provided.
+# Schema for CPU topology configuration. A missing value lets QEMU
+# figure out a suitable value based on the ones that are provided.
#
# @cpus: number of virtual CPUs in the virtual machine
#
@@ -1297,7 +1297,7 @@
#
# @dies: number of dies per socket in the CPU topology
#
-# @cores: number of cores per thread in the CPU topology
+# @cores: number of cores per die in the CPU topology
#
# @threads: number of threads per core in the CPU topology
#
diff --git a/qemu-options.hx b/qemu-options.hx
index 99ed5ec5f1..e077aa80bf 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -223,11 +223,13 @@ SRST
of computing the CPU maximum count.
Either the initial CPU count, or at least one of the topology parameters
- must be specified. Values for any omitted parameters will be computed
- from those which are given. Historically preference was given to the
- coarsest topology parameters when computing missing values (ie sockets
- preferred over cores, which were preferred over threads), however, this
- behaviour is considered liable to change.
+ must be specified. The specified parameters must be greater than zero,
+ explicit configuration like "cpus=0" is not allowed. Values for any
+ omitted parameters will be computed from those which are given.
+ Historically preference was given to the coarsest topology parameters
+ when computing missing values (ie sockets preferred over cores, which
+ were preferred over threads), however, this behaviour is considered
+ liable to change.
ERST
DEF("numa", HAS_ARG, QEMU_OPTION_numa,
--
2.19.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH for-6.1 v5 1/1] machine: Disallow specifying topology parameters as zero
2021-07-23 9:57 ` [PATCH for-6.1 v5 1/1] " Yanan Wang
@ 2021-08-06 8:27 ` wangyanan (Y)
0 siblings, 0 replies; 3+ messages in thread
From: wangyanan (Y) @ 2021-08-06 8:27 UTC (permalink / raw)
To: qemu-devel, Eduardo Habkost, Marcel Apfelbaum, Paolo Bonzini
Cc: Peter Maydell, Andrew Jones, Daniel P . Berrangé,
Pierre Morel, Pankaj Gupta, Cornelia Huck, Markus Armbruster,
Cleber Rosa, yuzenghui, wanghaibin.wang
A gentle ping ...
Will this patch be picked up soon for 6.1 or is there anything else to
tweak?
Thanks,
Yanan
On 2021/7/23 17:57, Yanan Wang wrote:
> In the SMP configuration, we should either specify a topology
> parameter with a reasonable value (equal to or greater than 1)
> or just leave it omitted and QEMU will calculate its value.
> Configurations which explicitly specify the topology parameters
> as zero like "sockets=0" are meaningless, so disallow them.
>
> However, the commit 1e63fe685804d
> (machine: pass QAPI struct to mc->smp_parse) has documented that
> '0' has the same semantics as omitting a parameter in the qapi
> comment for SMPConfiguration. So this patch fixes the doc and
> also adds the corresponding sanity check.
>
> Reviewed-by: Cornelia Huck <cohuck@redhat.com>
> Reviewed-by: Andrew Jones <drjones@redhat.com>
> Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
> Tested-by: Daniel P. Berrange <berrange@redhat.com>
> Suggested-by: Andrew Jones <drjones@redhat.com>
> Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
> ---
> hw/core/machine.c | 14 ++++++++++++++
> qapi/machine.json | 6 +++---
> qemu-options.hx | 12 +++++++-----
> 3 files changed, 24 insertions(+), 8 deletions(-)
>
> diff --git a/hw/core/machine.c b/hw/core/machine.c
> index 775add0795..e1533dfc47 100644
> --- a/hw/core/machine.c
> +++ b/hw/core/machine.c
> @@ -829,6 +829,20 @@ static void machine_set_smp(Object *obj, Visitor *v, const char *name,
> return;
> }
>
> + /*
> + * The CPU topology parameters must be specified greater than zero or
> + * just omitted, explicit configuration like "cpus=0" is not allowed.
> + */
> + if ((config->has_cpus && config->cpus == 0) ||
> + (config->has_sockets && config->sockets == 0) ||
> + (config->has_dies && config->dies == 0) ||
> + (config->has_cores && config->cores == 0) ||
> + (config->has_threads && config->threads == 0) ||
> + (config->has_maxcpus && config->maxcpus == 0)) {
> + error_setg(errp, "CPU topology parameters must be greater than zero");
> + goto out_free;
> + }
> +
> mc->smp_parse(ms, config, errp);
> if (errp) {
> goto out_free;
> diff --git a/qapi/machine.json b/qapi/machine.json
> index c3210ee1fb..9272cb3cf8 100644
> --- a/qapi/machine.json
> +++ b/qapi/machine.json
> @@ -1288,8 +1288,8 @@
> ##
> # @SMPConfiguration:
> #
> -# Schema for CPU topology configuration. "0" or a missing value lets
> -# QEMU figure out a suitable value based on the ones that are provided.
> +# Schema for CPU topology configuration. A missing value lets QEMU
> +# figure out a suitable value based on the ones that are provided.
> #
> # @cpus: number of virtual CPUs in the virtual machine
> #
> @@ -1297,7 +1297,7 @@
> #
> # @dies: number of dies per socket in the CPU topology
> #
> -# @cores: number of cores per thread in the CPU topology
> +# @cores: number of cores per die in the CPU topology
> #
> # @threads: number of threads per core in the CPU topology
> #
> diff --git a/qemu-options.hx b/qemu-options.hx
> index 99ed5ec5f1..e077aa80bf 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -223,11 +223,13 @@ SRST
> of computing the CPU maximum count.
>
> Either the initial CPU count, or at least one of the topology parameters
> - must be specified. Values for any omitted parameters will be computed
> - from those which are given. Historically preference was given to the
> - coarsest topology parameters when computing missing values (ie sockets
> - preferred over cores, which were preferred over threads), however, this
> - behaviour is considered liable to change.
> + must be specified. The specified parameters must be greater than zero,
> + explicit configuration like "cpus=0" is not allowed. Values for any
> + omitted parameters will be computed from those which are given.
> + Historically preference was given to the coarsest topology parameters
> + when computing missing values (ie sockets preferred over cores, which
> + were preferred over threads), however, this behaviour is considered
> + liable to change.
> ERST
>
> DEF("numa", HAS_ARG, QEMU_OPTION_numa,
^ permalink raw reply [flat|nested] 3+ messages in thread
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2021-08-06 8:27 ` wangyanan (Y)
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