* [PATCH for-6.1 v2 0/1] machine: Disallow specifying topology parameters as zero
@ 2021-07-22 15:43 Yanan Wang
2021-07-22 15:43 ` [PATCH for-6.1 v2] " Yanan Wang
0 siblings, 1 reply; 10+ messages in thread
From: Yanan Wang @ 2021-07-22 15:43 UTC (permalink / raw)
To: qemu-devel
Cc: Peter Maydell, Andrew Jones, Daniel P . Berrangé,
Eduardo Habkost, Pierre Morel, Pankaj Gupta, Cornelia Huck,
Markus Armbruster, Yanan Wang, wanghaibin.wang, 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 in the smp parsers.
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/
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] 10+ messages in thread
* [PATCH for-6.1 v2] machine: Disallow specifying topology parameters as zero
2021-07-22 15:43 [PATCH for-6.1 v2 0/1] machine: Disallow specifying topology parameters as zero Yanan Wang
@ 2021-07-22 15:43 ` Yanan Wang
2021-07-22 16:01 ` Daniel P. Berrangé
` (2 more replies)
0 siblings, 3 replies; 10+ messages in thread
From: Yanan Wang @ 2021-07-22 15:43 UTC (permalink / raw)
To: qemu-devel
Cc: Peter Maydell, Andrew Jones, Daniel P . Berrangé,
Eduardo Habkost, Pierre Morel, Pankaj Gupta, Cornelia Huck,
Markus Armbruster, Yanan Wang, wanghaibin.wang, 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 in the smp parsers.
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..db129d937b 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 topology parameters must be specified equal to or great than one
+ * 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, "parameters must be equal to or greater than one if provided");
+ 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..b0168f8c48 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 equal to or great
+ than one, 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] 10+ messages in thread
* Re: [PATCH for-6.1 v2] machine: Disallow specifying topology parameters as zero
2021-07-22 15:43 ` [PATCH for-6.1 v2] " Yanan Wang
@ 2021-07-22 16:01 ` Daniel P. Berrangé
2021-07-23 8:02 ` Markus Armbruster
2021-07-22 16:15 ` Andrew Jones
2021-07-22 22:25 ` Cleber Rosa
2 siblings, 1 reply; 10+ messages in thread
From: Daniel P. Berrangé @ 2021-07-22 16:01 UTC (permalink / raw)
To: Yanan Wang
Cc: Peter Maydell, Andrew Jones, Eduardo Habkost, Pierre Morel,
Pankaj Gupta, Cornelia Huck, qemu-devel, Markus Armbruster,
wanghaibin.wang, yuzenghui, Paolo Bonzini
On Thu, Jul 22, 2021 at 11:43:26PM +0800, 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 in the smp parsers.
>
> 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..db129d937b 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 topology parameters must be specified equal to or great than one
> + * 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, "parameters must be equal to or greater than one if provided");
I'd suggest a slight tweak since when seen it lacks context:
$ ./qemu-system-x86_64 -smp 4,cores=0,sockets=2
qemu-system-x86_64: parameters must be equal to or greater than one if provided
error_setg(errp, "CPU topology parameters must be equal to or greater than one if provided");
> diff --git a/qemu-options.hx b/qemu-options.hx
> index 99ed5ec5f1..b0168f8c48 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 equal to or great
s/great/greater/
> + than one, 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
If you make the text changes, then feel free to add this when posting v2:
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Tested-by: Daniel P. Berrangé <berrange@redhat.com>
Regards,
Daniel
--
|: https://berrange.com -o- https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org -o- https://fstop138.berrange.com :|
|: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH for-6.1 v2] machine: Disallow specifying topology parameters as zero
2021-07-22 15:43 ` [PATCH for-6.1 v2] " Yanan Wang
2021-07-22 16:01 ` Daniel P. Berrangé
@ 2021-07-22 16:15 ` Andrew Jones
2021-07-22 22:25 ` Cleber Rosa
2 siblings, 0 replies; 10+ messages in thread
From: Andrew Jones @ 2021-07-22 16:15 UTC (permalink / raw)
To: Yanan Wang
Cc: Peter Maydell, Daniel P . Berrangé,
Eduardo Habkost, Pierre Morel, Pankaj Gupta, Cornelia Huck,
qemu-devel, Markus Armbruster, wanghaibin.wang, yuzenghui,
Paolo Bonzini
On Thu, Jul 22, 2021 at 11:43:26PM +0800, 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 in the smp parsers.
>
> 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(-)
With Daniel's suggested changes for v3
Reviewed-by: Andrew Jones <drjones@redhat.com>
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH for-6.1 v2] machine: Disallow specifying topology parameters as zero
2021-07-22 15:43 ` [PATCH for-6.1 v2] " Yanan Wang
2021-07-22 16:01 ` Daniel P. Berrangé
2021-07-22 16:15 ` Andrew Jones
@ 2021-07-22 22:25 ` Cleber Rosa
2021-07-23 1:57 ` wangyanan (Y)
2 siblings, 1 reply; 10+ messages in thread
From: Cleber Rosa @ 2021-07-22 22:25 UTC (permalink / raw)
To: Yanan Wang
Cc: Peter Maydell, Andrew Jones, Daniel P . Berrangé,
Eduardo Habkost, Pierre Morel, Pankaj Gupta, Cornelia Huck,
Markus Armbruster, qemu-devel, Paolo Bonzini, yuzenghui,
wanghaibin.wang
Yanan Wang writes:
> 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 in the smp parsers.
>
> 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(-)
Hi Yanan,
This looks somewhat similar to this very old patch of mine:
https://mail.gnu.org/archive/html/qemu-devel/2020-10/msg03039.html
I'm putting a reference here because I believe the test can be salvaged
and slightly adapted for this patch of yours.
Let me know if I can help anyhow.
Thanks,
- Cleber.
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH for-6.1 v2] machine: Disallow specifying topology parameters as zero
2021-07-22 22:25 ` Cleber Rosa
@ 2021-07-23 1:57 ` wangyanan (Y)
2021-07-23 14:14 ` Cleber Rosa
0 siblings, 1 reply; 10+ messages in thread
From: wangyanan (Y) @ 2021-07-23 1:57 UTC (permalink / raw)
To: Cleber Rosa
Cc: Peter Maydell, Andrew Jones, Daniel P . Berrangé,
Eduardo Habkost, Pierre Morel, Pankaj Gupta, Cornelia Huck,
Markus Armbruster, qemu-devel, wanghaibin.wang, yuzenghui,
Paolo Bonzini
Hi Cleber,
On 2021/7/23 6:25, Cleber Rosa wrote:
> Yanan Wang writes:
>
>> 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 in the smp parsers.
>>
>> 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(-)
> Hi Yanan,
>
> This looks somewhat similar to this very old patch of mine:
>
> https://mail.gnu.org/archive/html/qemu-devel/2020-10/msg03039.html
>
> I'm putting a reference here because I believe the test can be salvaged
> and slightly adapted for this patch of yours.
>
> Let me know if I can help anyhow.
>
Thanks for this.
I was introducing an unit test for the smp parsing in [1], in which all
possible valid and invalid smp configs were covered, and actually the
"parameter=0" stuff was also covered. You can have a look, and
suggestions are welcome. I'm not sure we need two different tests
for the same part. :)
[1]
https://lore.kernel.org/qemu-devel/20210719032043.25416-12-wangyanan55@huawei.com/
Thanks,
Yanan
.
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH for-6.1 v2] machine: Disallow specifying topology parameters as zero
2021-07-22 16:01 ` Daniel P. Berrangé
@ 2021-07-23 8:02 ` Markus Armbruster
2021-07-23 8:40 ` wangyanan (Y)
0 siblings, 1 reply; 10+ messages in thread
From: Markus Armbruster @ 2021-07-23 8:02 UTC (permalink / raw)
To: Daniel P. Berrangé
Cc: Peter Maydell, Andrew Jones, Eduardo Habkost, Pierre Morel,
Pankaj Gupta, Cornelia Huck, qemu-devel, Yanan Wang,
wanghaibin.wang, yuzenghui, Paolo Bonzini
Daniel P. Berrangé <berrange@redhat.com> writes:
> On Thu, Jul 22, 2021 at 11:43:26PM +0800, 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 in the smp parsers.
>>
>> 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..db129d937b 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 topology parameters must be specified equal to or great than one
>> + * 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, "parameters must be equal to or greater than one if provided");
>
> I'd suggest a slight tweak since when seen it lacks context:
>
> $ ./qemu-system-x86_64 -smp 4,cores=0,sockets=2
> qemu-system-x86_64: parameters must be equal to or greater than one if provided
>
>
> error_setg(errp, "CPU topology parameters must be equal to or greater than one if provided");
Let's scratch "if provided".
I'd replace "must be equal to or greater than one" by "must be
positive", or maybe "must be greater than zero".
>> diff --git a/qemu-options.hx b/qemu-options.hx
>> index 99ed5ec5f1..b0168f8c48 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 equal to or great
>
> s/great/greater/
>
>> + than one, explicit configuration like "cpus=0" is not allowed. Values
"positive" again.
>> + 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
>
>
> If you make the text changes, then feel free to add this when posting v2:
>
> Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
> Tested-by: Daniel P. Berrangé <berrange@redhat.com>
>
>
>
> Regards,
> Daniel
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH for-6.1 v2] machine: Disallow specifying topology parameters as zero
2021-07-23 8:02 ` Markus Armbruster
@ 2021-07-23 8:40 ` wangyanan (Y)
2021-07-23 8:46 ` Cornelia Huck
0 siblings, 1 reply; 10+ messages in thread
From: wangyanan (Y) @ 2021-07-23 8:40 UTC (permalink / raw)
To: Markus Armbruster, Daniel P. Berrangé
Cc: Peter Maydell, Andrew Jones, Eduardo Habkost, Pierre Morel,
Pankaj Gupta, Cornelia Huck, qemu-devel, wanghaibin.wang,
yuzenghui, Paolo Bonzini
On 2021/7/23 16:02, Markus Armbruster wrote:
> Daniel P. Berrangé <berrange@redhat.com> writes:
>
>> On Thu, Jul 22, 2021 at 11:43:26PM +0800, 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 in the smp parsers.
>>>
>>> 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..db129d937b 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 topology parameters must be specified equal to or great than one
>>> + * 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, "parameters must be equal to or greater than one if provided");
>> I'd suggest a slight tweak since when seen it lacks context:
>>
>> $ ./qemu-system-x86_64 -smp 4,cores=0,sockets=2
>> qemu-system-x86_64: parameters must be equal to or greater than one if provided
>>
>>
>> error_setg(errp, "CPU topology parameters must be equal to or greater than one if provided");
> Let's scratch "if provided".
>
> I'd replace "must be equal to or greater than one" by "must be
> positive", or maybe "must be greater than zero".
How about we use "must be greater than zero" ?
After a grep search of these two sentences in QEMU, they both show up
in several places. "must be positive" always reports an invalid value that
is "< 0". While the check in this patch actually reject an invalid zero
value.
>>> diff --git a/qemu-options.hx b/qemu-options.hx
>>> index 99ed5ec5f1..b0168f8c48 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 equal to or great
>> s/great/greater/
>>
>>> + than one, explicit configuration like "cpus=0" is not allowed. Values
> "positive" again.
Thanks,
Yanan
>>> + 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
>>
>> If you make the text changes, then feel free to add this when posting v2:
>>
>> Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
>> Tested-by: Daniel P. Berrangé <berrange@redhat.com>
>>
>>
>>
>> Regards,
>> Daniel
> .
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH for-6.1 v2] machine: Disallow specifying topology parameters as zero
2021-07-23 8:40 ` wangyanan (Y)
@ 2021-07-23 8:46 ` Cornelia Huck
0 siblings, 0 replies; 10+ messages in thread
From: Cornelia Huck @ 2021-07-23 8:46 UTC (permalink / raw)
To: wangyanan (Y), Markus Armbruster, Daniel P. Berrangé
Cc: Peter Maydell, Andrew Jones, Eduardo Habkost, Pierre Morel,
Pankaj Gupta, qemu-devel, wanghaibin.wang, yuzenghui,
Paolo Bonzini
On Fri, Jul 23 2021, "wangyanan (Y)" <wangyanan55@huawei.com> wrote:
> On 2021/7/23 16:02, Markus Armbruster wrote:
>> Daniel P. Berrangé <berrange@redhat.com> writes:
>>
>>> On Thu, Jul 22, 2021 at 11:43:26PM +0800, Yanan Wang wrote:
>>>> + /*
>>>> + * The topology parameters must be specified equal to or great than one
>>>> + * 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, "parameters must be equal to or greater than one if provided");
>>> I'd suggest a slight tweak since when seen it lacks context:
>>>
>>> $ ./qemu-system-x86_64 -smp 4,cores=0,sockets=2
>>> qemu-system-x86_64: parameters must be equal to or greater than one if provided
>>>
>>>
>>> error_setg(errp, "CPU topology parameters must be equal to or greater than one if provided");
>> Let's scratch "if provided".
>>
>> I'd replace "must be equal to or greater than one" by "must be
>> positive", or maybe "must be greater than zero".
> How about we use "must be greater than zero" ?
> After a grep search of these two sentences in QEMU, they both show up
> in several places. "must be positive" always reports an invalid value that
> is "< 0". While the check in this patch actually reject an invalid zero
> value.
Of the two, I'd prefer "greater than zero".
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH for-6.1 v2] machine: Disallow specifying topology parameters as zero
2021-07-23 1:57 ` wangyanan (Y)
@ 2021-07-23 14:14 ` Cleber Rosa
0 siblings, 0 replies; 10+ messages in thread
From: Cleber Rosa @ 2021-07-23 14:14 UTC (permalink / raw)
To: wangyanan (Y)
Cc: Peter Maydell, Andrew Jones, Daniel P . Berrangé,
Eduardo Habkost, Pierre Morel, Pankaj Gupta, Cornelia Huck,
Markus Armbruster, qemu-devel, wanghaibin.wang, yuzenghui,
Paolo Bonzini
wangyanan (Y) writes:
> Hi Cleber,
>
> On 2021/7/23 6:25, Cleber Rosa wrote:
>> Yanan Wang writes:
>>
>>> 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 in the smp parsers.
>>>
>>> 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(-)
>> Hi Yanan,
>>
>> This looks somewhat similar to this very old patch of mine:
>>
>> https://mail.gnu.org/archive/html/qemu-devel/2020-10/msg03039.html
>>
>> I'm putting a reference here because I believe the test can be salvaged
>> and slightly adapted for this patch of yours.
>>
>> Let me know if I can help anyhow.
>>
> Thanks for this.
> I was introducing an unit test for the smp parsing in [1], in which all
> possible valid and invalid smp configs were covered, and actually the
> "parameter=0" stuff was also covered. You can have a look, and
> suggestions are welcome. I'm not sure we need two different tests
> for the same part. :)
>
Right, I only saw the other series later. Nice work there!
- Cleber.
^ permalink raw reply [flat|nested] 10+ messages in thread
end of thread, other threads:[~2021-07-23 14:16 UTC | newest]
Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-07-22 15:43 [PATCH for-6.1 v2 0/1] machine: Disallow specifying topology parameters as zero Yanan Wang
2021-07-22 15:43 ` [PATCH for-6.1 v2] " Yanan Wang
2021-07-22 16:01 ` Daniel P. Berrangé
2021-07-23 8:02 ` Markus Armbruster
2021-07-23 8:40 ` wangyanan (Y)
2021-07-23 8:46 ` Cornelia Huck
2021-07-22 16:15 ` Andrew Jones
2021-07-22 22:25 ` Cleber Rosa
2021-07-23 1:57 ` wangyanan (Y)
2021-07-23 14:14 ` Cleber Rosa
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