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

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(-)

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>