Denis Kirjanov <k...@linux-powerpc.org> writes:
> With CONFIG_DEBUG_PREEMPT enabled we see the following trace:
>
> [ 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
>
> Disable preemption while accessing paca struct to avoid inconsistent state
>
> Fixes: f725758 ("KVM: PPC: Book3S HV: Use OPAL XICS emulation on POWER9")
> Signed-off-by: Denis Kirjanov <k...@linux-powerpc.org>
> ---
> arch/powerpc/kvm/book3s_hv.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
> index 1ec86d9..8e96bab 100644
> --- a/arch/powerpc/kvm/book3s_hv.c
> +++ b/arch/powerpc/kvm/book3s_hv.c
> @@ -3913,6 +3913,10 @@ static int kvmppc_radix_possible(void)
> static int kvmppc_book3s_init_hv(void)
> {
> int r;
> +#ifdef CONFIG_SMP
> + unsigned long xics_phys;
> +#endif
> +
> /*
> * FIXME!! Do we need to check on all cpus ?
> */
> @@ -3930,7 +3934,11 @@ static int kvmppc_book3s_init_hv(void)
> * indirectly, via OPAL.
> */
> #ifdef CONFIG_SMP
> - if (!get_paca()->kvm_hstate.xics_phys) {
> + preempt_disable();
> + xics_phys = get_paca()->kvm_hstate.xics_phys;
> + preempt_enable();
> +
> + if (!xics_phys) {
> struct device_node *np;
Can you tell me what actual problem (other than the warning) this is
fixing?
cheers
