kvmppc: BUG: using smp_processor_id() in preemptible

[Denis Kirjanov]

[Now with the proper subject]

Hi,

the commit 5a319350a46572d073042a3194676099dd2c135d
has introduces the following warning with CONFIG_DEBUG_PREEMPT enabled:

[  129.314426] BUG: using smp_processor_id() in preemptible [00000000]
code: modprobe/5459
[  129.314580] caller is .kvmppc_book3s_init_hv+0x184/0x350 [kvm_hv]
[  129.314697] CPU: 11 PID: 5459 Comm: modprobe Not tainted
4.11.0-rc3-00022-gc7e790c #1
[  129.314848] Call Trace:
[  129.314915] [c0000007d624b810] [c0000000023eef10]
.dump_stack+0xe4/0x150 (unreliable)
[  129.315065] [c0000007d624b8a0] [c000000001f6ec04]
.check_preemption_disabled+0x134/0x150
[  129.315210] [c0000007d624b940] [d00000000a010274]
.kvmppc_book3s_init_hv+0x184/0x350 [kvm_hv]
[  129.315339] [c0000007d624ba00] [c00000000191d5cc] .do_one_initcall+0x5c/0x1c0
[  129.315416] [c0000007d624bad0] [c0000000023e9494] .do_init_module+0x84/0x240
[  129.315492] [c0000007d624bb70] [c000000001aade18] .load_module+0x1f68/0x2a10
[  129.315568] [c0000007d624bd20] [c000000001aaeb30] .SyS_finit_module+0xc0/0xf0
[  129.315645] [c0000007d624be30] [c00000000191baec] system_call+0x38/0xfc

I think that we have to explicitly add a call to preempt_disable to
the get_paca() macro with the CONFIG_DEBUG_PREEMPT enabled.

Probably we need to create a common accessor function since we already
have a special cases like svcpu_get/svcpu_put

If you agree I'm going send a patch.

Thanks!