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.

Suggested-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
---
 hw/core/machine.c | 31 +++++++++++++++++++++++--------
 hw/i386/pc.c      | 29 +++++++++++++++++++++--------
 qapi/machine.json |  4 ++--
 3 files changed, 46 insertions(+), 18 deletions(-)

diff --git a/hw/core/machine.c b/hw/core/machine.c
index 775add0795..d73daa10f4 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -745,11 +745,25 @@ static void smp_parse(MachineState *ms, SMPConfiguration *config, Error **errp)
 {
     unsigned cpus    = config->has_cpus ? config->cpus : 0;
     unsigned sockets = config->has_sockets ? config->sockets : 0;
+    unsigned dies    = config->has_dies ? config->dies : 1;
     unsigned cores   = config->has_cores ? config->cores : 0;
     unsigned threads = config->has_threads ? config->threads : 0;
+    unsigned maxcpus = config->has_maxcpus ? config->maxcpus : 0;
+
+    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");
+        return;
+    }
 
-    if (config->has_dies && config->dies != 0 && config->dies != 1) {
+    if (dies > 1) {
         error_setg(errp, "dies not supported by this machine's CPU topology");
+        return;
     }
 
     /* compute missing values, prefer sockets over cores over threads */
@@ -760,8 +774,8 @@ static void smp_parse(MachineState *ms, SMPConfiguration *config, Error **errp)
             sockets = sockets > 0 ? sockets : 1;
             cpus = cores * threads * sockets;
         } else {
-            ms->smp.max_cpus = config->has_maxcpus ? config->maxcpus : cpus;
-            sockets = ms->smp.max_cpus / (cores * threads);
+            maxcpus = maxcpus > 0 ? maxcpus : cpus;
+            sockets = maxcpus / (cores * threads);
         }
     } else if (cores == 0) {
         threads = threads > 0 ? threads : 1;
@@ -778,26 +792,27 @@ static void smp_parse(MachineState *ms, SMPConfiguration *config, Error **errp)
         return;
     }
 
-    ms->smp.max_cpus = config->has_maxcpus ? config->maxcpus : cpus;
+    maxcpus = maxcpus > 0 ? maxcpus : cpus;
 
-    if (ms->smp.max_cpus < cpus) {
+    if (maxcpus < cpus) {
         error_setg(errp, "maxcpus must be equal to or greater than smp");
         return;
     }
 
-    if (sockets * cores * threads != ms->smp.max_cpus) {
+    if (sockets * cores * threads != maxcpus) {
         error_setg(errp, "Invalid CPU topology: "
                    "sockets (%u) * cores (%u) * threads (%u) "
                    "!= maxcpus (%u)",
                    sockets, cores, threads,
-                   ms->smp.max_cpus);
+                   maxcpus);
         return;
     }
 
     ms->smp.cpus = cpus;
+    ms->smp.sockets = sockets;
     ms->smp.cores = cores;
     ms->smp.threads = threads;
-    ms->smp.sockets = sockets;
+    ms->smp.max_cpus = maxcpus;
 }
 
 static void machine_get_smp(Object *obj, Visitor *v, const char *name,
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index c2b9d62a35..c6b63c00a5 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -719,6 +719,18 @@ static void pc_smp_parse(MachineState *ms, SMPConfiguration *config, Error **err
     unsigned dies    = config->has_dies ? config->dies : 1;
     unsigned cores   = config->has_cores ? config->cores : 0;
     unsigned threads = config->has_threads ? config->threads : 0;
+    unsigned maxcpus = config->has_maxcpus ? config->maxcpus : 0;
+
+    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");
+        return;
+    }
 
     /* compute missing values, prefer sockets over cores over threads */
     if (cpus == 0 || sockets == 0) {
@@ -728,8 +740,8 @@ static void pc_smp_parse(MachineState *ms, SMPConfiguration *config, Error **err
             sockets = sockets > 0 ? sockets : 1;
             cpus = cores * threads * dies * sockets;
         } else {
-            ms->smp.max_cpus = config->has_maxcpus ? config->maxcpus : cpus;
-            sockets = ms->smp.max_cpus / (cores * threads * dies);
+            maxcpus = maxcpus > 0 ? maxcpus : cpus;
+            sockets = maxcpus / (cores * threads * dies);
         }
     } else if (cores == 0) {
         threads = threads > 0 ? threads : 1;
@@ -746,27 +758,28 @@ static void pc_smp_parse(MachineState *ms, SMPConfiguration *config, Error **err
         return;
     }
 
-    ms->smp.max_cpus = config->has_maxcpus ? config->maxcpus : cpus;
+    maxcpus = maxcpus > 0 ? maxcpus : cpus;
 
-    if (ms->smp.max_cpus < cpus) {
+    if (maxcpus < cpus) {
         error_setg(errp, "maxcpus must be equal to or greater than smp");
         return;
     }
 
-    if (sockets * dies * cores * threads != ms->smp.max_cpus) {
+    if (sockets * dies * cores * threads != maxcpus) {
         error_setg(errp, "Invalid CPU topology deprecated: "
                    "sockets (%u) * dies (%u) * cores (%u) * threads (%u) "
                    "!= maxcpus (%u)",
                    sockets, dies, cores, threads,
-                   ms->smp.max_cpus);
+                   maxcpus);
         return;
     }
 
     ms->smp.cpus = cpus;
-    ms->smp.cores = cores;
-    ms->smp.threads = threads;
     ms->smp.sockets = sockets;
     ms->smp.dies = dies;
+    ms->smp.cores = cores;
+    ms->smp.threads = threads;
+    ms->smp.max_cpus = maxcpus;
 }
 
 static
diff --git a/qapi/machine.json b/qapi/machine.json
index c3210ee1fb..c11b2e6f73 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
 #
-- 
2.19.1

On Mon, Jul 19, 2021 at 11:20:33AM +0800, Yanan Wang wrote:
> 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.
> 
> Suggested-by: Andrew Jones <drjones@redhat.com>
> Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
> ---
>  hw/core/machine.c | 31 +++++++++++++++++++++++--------
>  hw/i386/pc.c      | 29 +++++++++++++++++++++--------
>  qapi/machine.json |  4 ++--
>  3 files changed, 46 insertions(+), 18 deletions(-)
> 
> diff --git a/hw/core/machine.c b/hw/core/machine.c
> index 775add0795..d73daa10f4 100644
> --- a/hw/core/machine.c
> +++ b/hw/core/machine.c
> @@ -745,11 +745,25 @@ static void smp_parse(MachineState *ms, SMPConfiguration *config, Error **errp)
>  {
>      unsigned cpus    = config->has_cpus ? config->cpus : 0;
>      unsigned sockets = config->has_sockets ? config->sockets : 0;
> +    unsigned dies    = config->has_dies ? config->dies : 1;

It looks odd to set dies=1 by default at initially, when everything
else is set to 0.  I realize you're just copying existing pc_smp_parse
code in this respect, but I feel like could benefit from a separate
initialization with a comment to explain why we're hardcoding it
to 1....

>      unsigned cores   = config->has_cores ? config->cores : 0;
>      unsigned threads = config->has_threads ? config->threads : 0;
> +    unsigned maxcpus = config->has_maxcpus ? config->maxcpus : 0;
> +
> +    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");
> +        return;
> +    }
>  
> -    if (config->has_dies && config->dies != 0 && config->dies != 1) {
> +    if (dies > 1) {
>          error_setg(errp, "dies not supported by this machine's CPU topology");
> +        return;
>      }

.... eg how about here adding

     /* Never try to assign multiple dies when defaulting omitted topology */
     if (dies == 0) {
         dies = 1;
     }



> diff --git a/qapi/machine.json b/qapi/machine.json
> index c3210ee1fb..c11b2e6f73 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.

Hmm, so we had actually documented that '0' had the same semantics
as omitting a parameter. This was done in:

  commit 1e63fe685804dfadddd643bf3860b1a59702d4bf
  Author: Paolo Bonzini <pbonzini@redhat.com>
  Date:   Thu Jun 17 17:53:06 2021 +0200

    machine: pass QAPI struct to mc->smp_parse

which hasn't been released yet.

This was possible, but never documented, with the traditiaonl -smp
impl before it was qapi-ified. I think that historical behaviour
was simply a side effect of the QemuOpts impl rather than an
intentional design, hence not documented.

At the very least I think need to get rid of this bit of docs about
"0" before this release, otherwise we'll have stronger need to
consider a real deprecation process.

Regards,
Daniel
-- 
|: https://berrange.com      -o-    https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org         -o-            https://fstop138.berrange.com :|
|: https://entangle-photo.org    -o-    https://www.instagram.com/dberrange :|

On 2021/7/20 0:46, Daniel P. Berrangé wrote:
> On Mon, Jul 19, 2021 at 11:20:33AM +0800, Yanan Wang wrote:
>> 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.
>>
>> Suggested-by: Andrew Jones <drjones@redhat.com>
>> Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
>> ---
>>   hw/core/machine.c | 31 +++++++++++++++++++++++--------
>>   hw/i386/pc.c      | 29 +++++++++++++++++++++--------
>>   qapi/machine.json |  4 ++--
>>   3 files changed, 46 insertions(+), 18 deletions(-)
>>
>> diff --git a/hw/core/machine.c b/hw/core/machine.c
>> index 775add0795..d73daa10f4 100644
>> --- a/hw/core/machine.c
>> +++ b/hw/core/machine.c
>> @@ -745,11 +745,25 @@ static void smp_parse(MachineState *ms, SMPConfiguration *config, Error **errp)
>>   {
>>       unsigned cpus    = config->has_cpus ? config->cpus : 0;
>>       unsigned sockets = config->has_sockets ? config->sockets : 0;
>> +    unsigned dies    = config->has_dies ? config->dies : 1;
> It looks odd to set dies=1 by default at initially, when everything
> else is set to 0.  I realize you're just copying existing pc_smp_parse
> code in this respect, but I feel like could benefit from a separate
> initialization with a comment to explain why we're hardcoding it
> to 1....
>
>>       unsigned cores   = config->has_cores ? config->cores : 0;
>>       unsigned threads = config->has_threads ? config->threads : 0;
>> +    unsigned maxcpus = config->has_maxcpus ? config->maxcpus : 0;
>> +
>> +    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");
>> +        return;
>> +    }
>>   
>> -    if (config->has_dies && config->dies != 0 && config->dies != 1) {
>> +    if (dies > 1) {
>>           error_setg(errp, "dies not supported by this machine's CPU topology");
>> +        return;
>>       }
> .... eg how about here adding
>
>       /* Never try to assign multiple dies when defaulting omitted topology */
>       if (dies == 0) {
>           dies = 1;
>       }
Yeah, I agree to default dies to 0 like the other parameters at initially
and then explicitly assign it to 1 if omitted here. But I think this 
explicit
assignment should be in pc_smp_parse, because dies is never used in
the calculation in smp_parse yet except the front sanity-check.

So I think what should be updated for this patch is:
1) default dies to 0 at initially both in smp_parse and pc_smp_parse
2) then explicitly assign dies to 1 if it's omitted in pc_smp_parse
>
>
>> diff --git a/qapi/machine.json b/qapi/machine.json
>> index c3210ee1fb..c11b2e6f73 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.
> Hmm, so we had actually documented that '0' had the same semantics
> as omitting a parameter. This was done in:
>
>    commit 1e63fe685804dfadddd643bf3860b1a59702d4bf
>    Author: Paolo Bonzini <pbonzini@redhat.com>
>    Date:   Thu Jun 17 17:53:06 2021 +0200
>
>      machine: pass QAPI struct to mc->smp_parse
>
> which hasn't been released yet.
>
> This was possible, but never documented, with the traditiaonl -smp
> impl before it was qapi-ified. I think that historical behaviour
> was simply a side effect of the QemuOpts impl rather than an
> intentional design, hence not documented.
Agreed.
> At the very least I think need to get rid of this bit of docs about
> "0" before this release, otherwise we'll have stronger need to
> consider a real deprecation process.
If the doc needs to be fixed right now, then I think we'd better resend this
single patch separately for 6.1, including the doc fix and also the related
sanity-check in the parsers. Right?

Thanks,
Yanan
.

On Mon, Jul 19, 2021 at 11:20:33AM +0800, Yanan Wang wrote:
> 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.
> 
> Suggested-by: Andrew Jones <drjones@redhat.com>
> Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
> ---
>  hw/core/machine.c | 31 +++++++++++++++++++++++--------
>  hw/i386/pc.c      | 29 +++++++++++++++++++++--------
>  qapi/machine.json |  4 ++--
>  3 files changed, 46 insertions(+), 18 deletions(-)
> 
> diff --git a/hw/core/machine.c b/hw/core/machine.c
> index 775add0795..d73daa10f4 100644
> --- a/hw/core/machine.c
> +++ b/hw/core/machine.c
> @@ -745,11 +745,25 @@ static void smp_parse(MachineState *ms, SMPConfiguration *config, Error **errp)
>  {
>      unsigned cpus    = config->has_cpus ? config->cpus : 0;
>      unsigned sockets = config->has_sockets ? config->sockets : 0;
> +    unsigned dies    = config->has_dies ? config->dies : 1;
>      unsigned cores   = config->has_cores ? config->cores : 0;
>      unsigned threads = config->has_threads ? config->threads : 0;
> +    unsigned maxcpus = config->has_maxcpus ? config->maxcpus : 0;
> +
> +    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");

Missing a space between 'one' and 'if'. It's better to just put the whole
string on one line too (ignore the 80 char thing) for error grepping.

> +        return;
> +    }
>  
> -    if (config->has_dies && config->dies != 0 && config->dies != 1) {
> +    if (dies > 1) {
>          error_setg(errp, "dies not supported by this machine's CPU topology");
> +        return;
>      }
>  
>      /* compute missing values, prefer sockets over cores over threads */
> @@ -760,8 +774,8 @@ static void smp_parse(MachineState *ms, SMPConfiguration *config, Error **errp)
>              sockets = sockets > 0 ? sockets : 1;
>              cpus = cores * threads * sockets;
>          } else {
> -            ms->smp.max_cpus = config->has_maxcpus ? config->maxcpus : cpus;
> -            sockets = ms->smp.max_cpus / (cores * threads);
> +            maxcpus = maxcpus > 0 ? maxcpus : cpus;
> +            sockets = maxcpus / (cores * threads);
>          }
>      } else if (cores == 0) {
>          threads = threads > 0 ? threads : 1;
> @@ -778,26 +792,27 @@ static void smp_parse(MachineState *ms, SMPConfiguration *config, Error **errp)
>          return;
>      }
>  
> -    ms->smp.max_cpus = config->has_maxcpus ? config->maxcpus : cpus;
> +    maxcpus = maxcpus > 0 ? maxcpus : cpus;
>  
> -    if (ms->smp.max_cpus < cpus) {
> +    if (maxcpus < cpus) {
>          error_setg(errp, "maxcpus must be equal to or greater than smp");
>          return;
>      }
>  
> -    if (sockets * cores * threads != ms->smp.max_cpus) {
> +    if (sockets * cores * threads != maxcpus) {
>          error_setg(errp, "Invalid CPU topology: "
>                     "sockets (%u) * cores (%u) * threads (%u) "
>                     "!= maxcpus (%u)",
>                     sockets, cores, threads,
> -                   ms->smp.max_cpus);
> +                   maxcpus);
>          return;
>      }
>  
>      ms->smp.cpus = cpus;
> +    ms->smp.sockets = sockets;
>      ms->smp.cores = cores;
>      ms->smp.threads = threads;
> -    ms->smp.sockets = sockets;
> +    ms->smp.max_cpus = maxcpus;
>  }
>  
>  static void machine_get_smp(Object *obj, Visitor *v, const char *name,
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index c2b9d62a35..c6b63c00a5 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -719,6 +719,18 @@ static void pc_smp_parse(MachineState *ms, SMPConfiguration *config, Error **err
>      unsigned dies    = config->has_dies ? config->dies : 1;
>      unsigned cores   = config->has_cores ? config->cores : 0;
>      unsigned threads = config->has_threads ? config->threads : 0;
> +    unsigned maxcpus = config->has_maxcpus ? config->maxcpus : 0;
> +
> +    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");

Same comment as above.

> +        return;
> +    }
>  
>      /* compute missing values, prefer sockets over cores over threads */
>      if (cpus == 0 || sockets == 0) {
> @@ -728,8 +740,8 @@ static void pc_smp_parse(MachineState *ms, SMPConfiguration *config, Error **err
>              sockets = sockets > 0 ? sockets : 1;
>              cpus = cores * threads * dies * sockets;
>          } else {
> -            ms->smp.max_cpus = config->has_maxcpus ? config->maxcpus : cpus;
> -            sockets = ms->smp.max_cpus / (cores * threads * dies);
> +            maxcpus = maxcpus > 0 ? maxcpus : cpus;
> +            sockets = maxcpus / (cores * threads * dies);
>          }
>      } else if (cores == 0) {
>          threads = threads > 0 ? threads : 1;
> @@ -746,27 +758,28 @@ static void pc_smp_parse(MachineState *ms, SMPConfiguration *config, Error **err
>          return;
>      }
>  
> -    ms->smp.max_cpus = config->has_maxcpus ? config->maxcpus : cpus;
> +    maxcpus = maxcpus > 0 ? maxcpus : cpus;
>  
> -    if (ms->smp.max_cpus < cpus) {
> +    if (maxcpus < cpus) {
>          error_setg(errp, "maxcpus must be equal to or greater than smp");
>          return;
>      }
>  
> -    if (sockets * dies * cores * threads != ms->smp.max_cpus) {
> +    if (sockets * dies * cores * threads != maxcpus) {
>          error_setg(errp, "Invalid CPU topology deprecated: "
>                     "sockets (%u) * dies (%u) * cores (%u) * threads (%u) "
>                     "!= maxcpus (%u)",
>                     sockets, dies, cores, threads,
> -                   ms->smp.max_cpus);
> +                   maxcpus);
>          return;
>      }
>  
>      ms->smp.cpus = cpus;
> -    ms->smp.cores = cores;
> -    ms->smp.threads = threads;
>      ms->smp.sockets = sockets;
>      ms->smp.dies = dies;
> +    ms->smp.cores = cores;
> +    ms->smp.threads = threads;
> +    ms->smp.max_cpus = maxcpus;
>  }
>  
>  static
> diff --git a/qapi/machine.json b/qapi/machine.json
> index c3210ee1fb..c11b2e6f73 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
>  #
> -- 
> 2.19.1
> 

Otherwise

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

On 2021/7/20 0:11, Andrew Jones wrote:
> On Mon, Jul 19, 2021 at 11:20:33AM +0800, Yanan Wang wrote:
>> 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.
>>
>> Suggested-by: Andrew Jones <drjones@redhat.com>
>> Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
>> ---
>>   hw/core/machine.c | 31 +++++++++++++++++++++++--------
>>   hw/i386/pc.c      | 29 +++++++++++++++++++++--------
>>   qapi/machine.json |  4 ++--
>>   3 files changed, 46 insertions(+), 18 deletions(-)
>>
>> diff --git a/hw/core/machine.c b/hw/core/machine.c
>> index 775add0795..d73daa10f4 100644
>> --- a/hw/core/machine.c
>> +++ b/hw/core/machine.c
>> @@ -745,11 +745,25 @@ static void smp_parse(MachineState *ms, SMPConfiguration *config, Error **errp)
>>   {
>>       unsigned cpus    = config->has_cpus ? config->cpus : 0;
>>       unsigned sockets = config->has_sockets ? config->sockets : 0;
>> +    unsigned dies    = config->has_dies ? config->dies : 1;
>>       unsigned cores   = config->has_cores ? config->cores : 0;
>>       unsigned threads = config->has_threads ? config->threads : 0;
>> +    unsigned maxcpus = config->has_maxcpus ? config->maxcpus : 0;
>> +
>> +    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");
> Missing a space between 'one' and 'if'. It's better to just put the whole
> string on one line too (ignore the 80 char thing) for error grepping.
>
>> +        return;
>> +    }
>>   
>> -    if (config->has_dies && config->dies != 0 && config->dies != 1) {
>> +    if (dies > 1) {
>>           error_setg(errp, "dies not supported by this machine's CPU topology");
>> +        return;
>>       }
>>   
>>       /* compute missing values, prefer sockets over cores over threads */
>> @@ -760,8 +774,8 @@ static void smp_parse(MachineState *ms, SMPConfiguration *config, Error **errp)
>>               sockets = sockets > 0 ? sockets : 1;
>>               cpus = cores * threads * sockets;
>>           } else {
>> -            ms->smp.max_cpus = config->has_maxcpus ? config->maxcpus : cpus;
>> -            sockets = ms->smp.max_cpus / (cores * threads);
>> +            maxcpus = maxcpus > 0 ? maxcpus : cpus;
>> +            sockets = maxcpus / (cores * threads);
>>           }
>>       } else if (cores == 0) {
>>           threads = threads > 0 ? threads : 1;
>> @@ -778,26 +792,27 @@ static void smp_parse(MachineState *ms, SMPConfiguration *config, Error **errp)
>>           return;
>>       }
>>   
>> -    ms->smp.max_cpus = config->has_maxcpus ? config->maxcpus : cpus;
>> +    maxcpus = maxcpus > 0 ? maxcpus : cpus;
>>   
>> -    if (ms->smp.max_cpus < cpus) {
>> +    if (maxcpus < cpus) {
>>           error_setg(errp, "maxcpus must be equal to or greater than smp");
>>           return;
>>       }
>>   
>> -    if (sockets * cores * threads != ms->smp.max_cpus) {
>> +    if (sockets * cores * threads != maxcpus) {
>>           error_setg(errp, "Invalid CPU topology: "
>>                      "sockets (%u) * cores (%u) * threads (%u) "
>>                      "!= maxcpus (%u)",
>>                      sockets, cores, threads,
>> -                   ms->smp.max_cpus);
>> +                   maxcpus);
>>           return;
>>       }
>>   
>>       ms->smp.cpus = cpus;
>> +    ms->smp.sockets = sockets;
>>       ms->smp.cores = cores;
>>       ms->smp.threads = threads;
>> -    ms->smp.sockets = sockets;
>> +    ms->smp.max_cpus = maxcpus;
>>   }
>>   
>>   static void machine_get_smp(Object *obj, Visitor *v, const char *name,
>> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
>> index c2b9d62a35..c6b63c00a5 100644
>> --- a/hw/i386/pc.c
>> +++ b/hw/i386/pc.c
>> @@ -719,6 +719,18 @@ static void pc_smp_parse(MachineState *ms, SMPConfiguration *config, Error **err
>>       unsigned dies    = config->has_dies ? config->dies : 1;
>>       unsigned cores   = config->has_cores ? config->cores : 0;
>>       unsigned threads = config->has_threads ? config->threads : 0;
>> +    unsigned maxcpus = config->has_maxcpus ? config->maxcpus : 0;
>> +
>> +    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");
> Same comment as above.
Ok, I will fix them.
>> +        return;
>> +    }
>>   
>>       /* compute missing values, prefer sockets over cores over threads */
>>       if (cpus == 0 || sockets == 0) {
>> @@ -728,8 +740,8 @@ static void pc_smp_parse(MachineState *ms, SMPConfiguration *config, Error **err
>>               sockets = sockets > 0 ? sockets : 1;
>>               cpus = cores * threads * dies * sockets;
>>           } else {
>> -            ms->smp.max_cpus = config->has_maxcpus ? config->maxcpus : cpus;
>> -            sockets = ms->smp.max_cpus / (cores * threads * dies);
>> +            maxcpus = maxcpus > 0 ? maxcpus : cpus;
>> +            sockets = maxcpus / (cores * threads * dies);
>>           }
>>       } else if (cores == 0) {
>>           threads = threads > 0 ? threads : 1;
>> @@ -746,27 +758,28 @@ static void pc_smp_parse(MachineState *ms, SMPConfiguration *config, Error **err
>>           return;
>>       }
>>   
>> -    ms->smp.max_cpus = config->has_maxcpus ? config->maxcpus : cpus;
>> +    maxcpus = maxcpus > 0 ? maxcpus : cpus;
>>   
>> -    if (ms->smp.max_cpus < cpus) {
>> +    if (maxcpus < cpus) {
>>           error_setg(errp, "maxcpus must be equal to or greater than smp");
>>           return;
>>       }
>>   
>> -    if (sockets * dies * cores * threads != ms->smp.max_cpus) {
>> +    if (sockets * dies * cores * threads != maxcpus) {
>>           error_setg(errp, "Invalid CPU topology deprecated: "
>>                      "sockets (%u) * dies (%u) * cores (%u) * threads (%u) "
>>                      "!= maxcpus (%u)",
>>                      sockets, dies, cores, threads,
>> -                   ms->smp.max_cpus);
>> +                   maxcpus);
>>           return;
>>       }
>>   
>>       ms->smp.cpus = cpus;
>> -    ms->smp.cores = cores;
>> -    ms->smp.threads = threads;
>>       ms->smp.sockets = sockets;
>>       ms->smp.dies = dies;
>> +    ms->smp.cores = cores;
>> +    ms->smp.threads = threads;
>> +    ms->smp.max_cpus = maxcpus;
>>   }
>>   
>>   static
>> diff --git a/qapi/machine.json b/qapi/machine.json
>> index c3210ee1fb..c11b2e6f73 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
>>   #
>> -- 
>> 2.19.1
>>
> Otherwise
>
> Reviewed-by: Andrew Jones <drjones@redhat.com>
>
> .
Thanks,
Yanan
.