Re: [PATCH for-6.2 v3 04/11] machine: Improve the error reporting of smp parsing

[Andrew Jones <drjones@redhat.com>]

On Wed, Jul 28, 2021 at 11:48:41AM +0800, Yanan Wang wrote:
> We have two requirements for a valid SMP configuration:
> the product of "sockets * cores * threads" must represent all the
> possible cpus, i.e., max_cpus, and then must include the initially
> present cpus, i.e., smp_cpus.
> 
> So we only need to ensure 1) "sockets * cores * threads == maxcpus"
> at first and then ensure 2) "maxcpus >= cpus". With a reasonable
> order of the sanity check, we can simplify the error reporting code.
> When reporting an error message we also report the exact value of
> each topology member to make users easily see what's going on.
> 
> Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
> ---
>  hw/core/machine.c | 22 +++++++++-------------
>  hw/i386/pc.c      | 24 ++++++++++--------------
>  2 files changed, 19 insertions(+), 27 deletions(-)
> 
> diff --git a/hw/core/machine.c b/hw/core/machine.c
> index 958e6e7107..e879163c3b 100644
> --- a/hw/core/machine.c
> +++ b/hw/core/machine.c
> @@ -777,25 +777,21 @@ static void smp_parse(MachineState *ms, SMPConfiguration *config, Error **errp)
>      maxcpus = maxcpus > 0 ? maxcpus : sockets * cores * threads;
>      cpus = cpus > 0 ? cpus : maxcpus;
>  
> -    if (sockets * cores * threads < cpus) {
> -        error_setg(errp, "cpu topology: "
> -                   "sockets (%u) * cores (%u) * threads (%u) < "
> -                   "smp_cpus (%u)",
> -                   sockets, cores, threads, cpus);
> +    if (sockets * cores * threads != maxcpus) {
> +        error_setg(errp, "Invalid CPU topology: "
> +                   "product of the hierarchy must match maxcpus: "
> +                   "sockets (%u) * cores (%u) * threads (%u) "
> +                   "!= maxcpus (%u)",
> +                   sockets, cores, threads, maxcpus);
>          return;
>      }
>  
>      if (maxcpus < cpus) {
> -        error_setg(errp, "maxcpus must be equal to or greater than smp");
> -        return;
> -    }
> -
> -    if (sockets * cores * threads != maxcpus) {
>          error_setg(errp, "Invalid CPU topology: "
> +                   "maxcpus must be equal to or greater than smp: "
>                     "sockets (%u) * cores (%u) * threads (%u) "
> -                   "!= maxcpus (%u)",
> -                   sockets, cores, threads,
> -                   maxcpus);
> +                   "== maxcpus (%u) < smp_cpus (%u)",
> +                   sockets, cores, threads, maxcpus, cpus);
>          return;
>      }
>  
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index 9ad7ae5254..3e403a7129 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -747,25 +747,21 @@ static void pc_smp_parse(MachineState *ms, SMPConfiguration *config, Error **err
>      maxcpus = maxcpus > 0 ? maxcpus : sockets * dies * cores * threads;
>      cpus = cpus > 0 ? cpus : maxcpus;
>  
> -    if (sockets * dies * cores * threads < cpus) {
> -        error_setg(errp, "cpu topology: "
> -                   "sockets (%u) * dies (%u) * cores (%u) * threads (%u) < "
> -                   "smp_cpus (%u)",
> -                   sockets, dies, cores, threads, cpus);
> +    if (sockets * cores * threads != maxcpus) {
> +        error_setg(errp, "Invalid CPU topology: "
> +                   "product of the hierarchy must match maxcpus: "
> +                   "sockets (%u) * dies (%u) * cores (%u) * threads (%u) "
> +                   "!= maxcpus (%u)",
> +                   sockets, dies, cores, threads, maxcpus);
>          return;
>      }
>  
>      if (maxcpus < cpus) {
> -        error_setg(errp, "maxcpus must be equal to or greater than smp");
> -        return;
> -    }
> -
> -    if (sockets * dies * cores * threads != maxcpus) {
> -        error_setg(errp, "Invalid CPU topology deprecated: "
> +        error_setg(errp, "Invalid CPU topology: "
> +                   "maxcpus must be equal to or greater than smp: "
>                     "sockets (%u) * dies (%u) * cores (%u) * threads (%u) "
> -                   "!= maxcpus (%u)",
> -                   sockets, dies, cores, threads,
> -                   maxcpus);
> +                   "== maxcpus (%u) < smp_cpus (%u)",
> +                   sockets, dies, cores, threads, maxcpus, cpus);
>          return;
>      }
>  
> -- 
> 2.19.1
>

 
Reviewed-by: Andrew Jones <drjones@redhat.com>