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 <drjo...@redhat.com> Signed-off-by: Yanan Wang <wangyana...@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