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ppc: Change Power9 compat table to support at most 8 threads/core 

Increases the max smt mode to 8 for Power9. That's because KVM supports
smt emulation in this platform so QEMU should allow users to use it as
well.

Today if we try to pass -smp ...,threads=8, QEMU will silently truncate
it to smt4 mode and may cause a crash if we try to perform a cpu
hotplug.

Signed-off-by: Jose Ricardo Ziviani <joserz@linux.vnet.ibm.com>
[dwg: Added an explanatory comment]
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
master
Jose Ricardo Ziviani 2018-01-14 17:23:48 -02:00 committed by David Gibson
parent 895d5cd620
commit 03ee51d354
1 changed files with 8 additions and 1 deletions
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9
target/ppc/compat.c
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@ -73,7 +73,14 @@ static const CompatInfo compat_table[] = {
.pvr = CPU_POWERPC_LOGICAL_3_00,
.pcr = PCR_COMPAT_3_00,
.pcr_level = PCR_COMPAT_3_00,
.max_threads = 4,
/*
* POWER9 hardware only supports 4 threads / core, but this
* limit is for guests. We need to support 8 vthreads/vcore
* on POWER9 for POWER8 compatibility guests, and it's very
* confusing if half of the threads disappear from the guest
* if it announces it's POWER9 aware at CAS time.
*/
.max_threads = 8,
},
};