How do we know that no one has ever used such configuration? The conversion
was meant to be bug-compatible.
Paolo
Il lun 16 ago 2021, 23:06 Eduardo Habkost <ehabk...@redhat.com> ha scritto:
> 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
>
>
