From: Yanan Wang <wangyana...@huawei.com> In the SMP configuration, we should either provide a topology parameter with a reasonable value (greater than zero) or just omit it and QEMU will compute the missing value. Users should have never provided a configuration with parameters as zero (e.g. -smp 8,sockets=0) which should be treated as invalid.
But commit 1e63fe68580 (machine: pass QAPI struct to mc->smp_parse) has added some doc which implied that 'anything=0' is valid and has the same semantics as omitting a parameter. To avoid meaningless configurations possibly introduced by users in the future and consequently a necessary deprecation process, fix the doc and also add the corresponding sanity check. Fixes: 1e63fe68580 (machine: pass QAPI struct to mc->smp_parse) Suggested-by: Andrew Jones <drjo...@redhat.com> Signed-off-by: Yanan Wang <wangyana...@huawei.com> Reviewed-by: Daniel P. Berrange <berra...@redhat.com> Tested-by: Daniel P. Berrange <berra...@redhat.com> Reviewed-by: Andrew Jones <drjo...@redhat.com> Reviewed-by: Cornelia Huck <coh...@redhat.com> Message-Id: <20210816024522.143124-2-wangyana...@huawei.com> Signed-off-by: Eduardo Habkost <ehabk...@redhat.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 54e040587dd..a7e119469aa 100644 --- a/hw/core/machine.c +++ b/hw/core/machine.c @@ -832,6 +832,20 @@ static void machine_set_smp(Object *obj, Visitor *v, const char *name, return; } + /* + * A specified topology parameter must be greater than zero, + * 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 c3210ee1fb2..9272cb3cf8b 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 83aa59a920f..aee622f577d 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -227,11 +227,13 @@ 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, -- 2.31.1