Re: [PATCH v15 06/11] s390x/cpu topology: interception of PTF instruction

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On 2/6/23 12:38, Thomas Huth wrote:
On 01/02/2023 14.20, Pierre Morel wrote:
When the host supports the CPU topology facility, the PTF
instruction with function code 2 is interpreted by the SIE,
provided that the userland hypervizor activates the interpretation

s/hypervizor/hypervisor/

grr, I was pretty sure you already said that to me and I did change it... seems I did not.

done now.


by using the KVM_CAP_S390_CPU_TOPOLOGY KVM extension.

The PTF instructions with function code 0 and 1 are intercepted
and must be emulated by the userland hypervizor.

dito

yes, thx.


During RESET all CPU of the configuration are placed in
horizontal polarity.

Signed-off-by: Pierre Morel <pmorel@xxxxxxxxxxxxx>
---
...
  /**
   * s390_topology_reset:
   *
   * Generic reset for CPU topology, calls s390_topology_reset()
   * s390_topology_reset() to reset the kernel Modified Topology
   * change record.
+ * Then set global and all CPUs polarity to POLARITY_HORIZONTAL.

You describe here already what's going to happen...

   */
  void s390_topology_reset(void)
  {
      s390_cpu_topology_reset();
+    /* Set global polarity to POLARITY_HORIZONTAL */

... then here again ...

+    s390_topology.polarity = POLARITY_HORIZONTAL;

... and the code is (fortunately) also very self-exaplaining...

+    /* Set all CPU polarity to POLARITY_HORIZONTAL */
+    s390_topology_set_cpus_polarity(POLARITY_HORIZONTAL);

... so I'd rather drop the two comments within the function body.

OK


  }

(rest of the patch looks fine to me)

  Thomas


Thanks.

Regards,
Pierre


--
Pierre Morel
IBM Lab Boeblingen



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