| Message ID | 20210722154326.1464-2-wangyanan55@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [for-6.1,v2] machine: Disallow specifying topology parameters as zero | expand |
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
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 .
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".
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.
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,
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(-)