v2:
- divided in two patches:
(1) enables smt8 mode to P9 guests
(2) checks if host supports the # of threads/core required
limitation: doesn't check guest running in compat mode
This patchset contains 2 changes:
(1) A P9 guest defined like -smp sockets=1,cores=1,threads=8 will be silently
changed to threads=4:
(guest) # lscpu
Architecture: ppc64le
Byte Order: Little Endian
CPU(s): 4
On-line CPU(s) list: 0-3
Thread(s) per core: 4
Core(s) per socket: 1
Socket(s): 1
NUMA node(s): 1
...
(qemu) info cpus
* CPU #0: nip=0xc0000000000db9cc thread_id=9440
CPU #1: nip=0xc0000000000db9cc thread_id=9441
CPU #2: nip=0xc0000000000db9cc thread_id=9442
CPU #3: nip=0xc0000000000db9cc thread_id=9443
CPU #4: nip=0x0000000000000100 (halted) thread_id=9444
CPU #5: nip=0x0000000000000100 (halted) thread_id=9445
CPU #6: nip=0x0000000000000100 (halted) thread_id=9446
CPU #7: nip=0x0000000000000100 (halted) thread_id=9447
This patch enables P9 guests to use emulated smt because KVM supports it:
(guest) # lscpu
Architecture: ppc64le
Byte Order: Little Endian
CPU(s): 8
On-line CPU(s) list: 0-7
Thread(s) per core: 8
Core(s) per socket: 1
Socket(s): 1
NUMA node(s): 1
(qemu) info cpus
* CPU #0: nip=0xc0000000000d30ac thread_id=68400
CPU #1: nip=0xc0000000000d30ac thread_id=68401
CPU #2: nip=0xc0000000000d30ac thread_id=68402
CPU #3: nip=0xc0000000000d30ac thread_id=68403
CPU #4: nip=0xc0000000000d30ac thread_id=68404
CPU #5: nip=0xc0000000000d30ac thread_id=68405
CPU #6: nip=0xc0000000000d30ac thread_id=68406
CPU #7: nip=0xc0000000000d30ac thread_id=68407
CPU hotplugging also works as expected:
(qemu) device_add host-spapr-cpu-core,id=core8,core-id=8
(qemu) info cpus
* CPU #0: nip=0xc0000000000d30ac thread_id=68400
CPU #1: nip=0xc0000000000d30ac thread_id=68401
CPU #2: nip=0xc0000000000d30ac thread_id=68402
CPU #3: nip=0xc0000000000d30ac thread_id=68403
CPU #4: nip=0xc0000000000d30ac thread_id=68404
CPU #5: nip=0xc0000000000d30ac thread_id=68405
CPU #6: nip=0xc0000000000d30ac thread_id=68406
CPU #7: nip=0xc0000000000d30ac thread_id=68407
CPU #8: nip=0xc0000000000d30ac thread_id=68492
CPU #9: nip=0xc0000000000d30ac thread_id=68493
CPU #10: nip=0xc0000000000d30ac thread_id=68494
CPU #11: nip=0xc0000000000d30ac thread_id=68495
CPU #12: nip=0xc0000000000d30ac thread_id=68496
CPU #13: nip=0xc0000000000d30ac thread_id=68497
CPU #14: nip=0xc0000000000d30ac thread_id=68498
CPU #15: nip=0xc0000000000d30ac thread_id=68499
(guest) # lscpu
Architecture: ppc64le
Byte Order: Little Endian
CPU(s): 16
On-line CPU(s) list: 0-15
Thread(s) per core: 8
Core(s) per socket: 2
Socket(s): 1
NUMA node(s): 1
(2) Checks if KVM supports the number of threads required
If users try to pass more threads/core than the host supports it displays an
error message and quits:
qemu-system-ppc64: KVM does not support 8 threads/core.
Available VSMT modes: 4 2 1.
Jose Ricardo Ziviani (2):
ppc: Change Power9 compat table to support at most 8 threads/core
ppc: spapr: Check if thread argument is supported by host KVM
hw/ppc/spapr.c | 10 ++++++++++
target/ppc/compat.c | 2 +-
target/ppc/kvm.c | 5 +++++
target/ppc/kvm_ppc.h | 6 ++++++
4 files changed, 22 insertions(+), 1 deletion(-)
--
2.14.3
