hw/core/machine.c | 14 ++++++++++++++ qapi/machine.json | 6 +++--- qemu-options.hx | 12 +++++++----- 3 files changed, 24 insertions(+), 8 deletions(-)
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
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 :|
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
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
> .
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".
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>
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.
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 .
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.
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