[PATCH v2 0/5] Hypervisor CPU Baseline Cleanups and Fixes

Collin Walling walling at linux.ibm.com
Fri Sep 25 00:22:34 UTC 2020

The following patches provide some TLC to the hypervisor CPU baseline
handler within the qemu_driver code.

#1 checks for the cpu-model-expansion capability before
executing the baseline handler since it is used for feature expansion.

#2 fixes a styling where a < 0 condition was missing from one of the 
if (function()) lines for consistency's sake.

#3 will check if the cpu definition(s) are valid and contain a model

#4 checks the cpu definition(s) model names against the model names
known by the hypervisor. This patch must come before #5.

#5 will allow the baseline command to be ran with a single cpu
definition, whereas before the command would simply fail with an
unhelpful error message. A CPU model expansion will be performed in
this case, which will produce the same result as if the model were
actually baselined.

Note: without patch #4, #5 can result in a segfault in the case where
a single CPU model is provided and the model is not recognized by the
hypervisor. This is because cpu model expansion will return 0 and the
result will be NULL. 

Since the QMP response returns "GenericError" in the case of a missing
CPU model, or if the command is not supported (and perhaps for other
reasons I am unsure of -- the response does not explicitly detail that
the CPU model provided was erroneous), we cannot rely on this 
response always meaning there was a missing CPU model.

So, to be safe-and-sure, the CPU model is checked against the list of
CPU models known to the hypervisor prior to baselining / expanding
(which were retrieved at some point previously during libvirt init).

Collin Walling (5):
  qemu: check for model-expansion cap before baselining
  qemu: fix one instance of rc check styling in baseline
  qemu: report error if missing model name when baselining
  qemu: check if cpu model is supported before baselining
  qemu: fix error message when baselining with a single cpu

 src/qemu/qemu_driver.c | 45 ++++++++++++++++++++++++++++++++++--------
 1 file changed, 37 insertions(+), 8 deletions(-)


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