Excerpts from Pratik Rajesh Sampat's message of July 10, 2020 3:22 pm:
> Additional registers DAWR0, DAWRX0 may be lost on Power 10 for
> stop levels < 4.
> Therefore save the values of these SPRs before entering a "stop"
> state and restore their values on wakeup.
Hmm, where do you get this from? Documentation I see says DAWR is lost
on POWER9 but not P10.
Does idle thread even need to save DAWR, or does it get switched when
going to a thread that has a watchpoint set?
Thanks,
Nick
>
> Signed-off-by: Pratik Rajesh Sampat <psam...@linux.ibm.com>
> ---
> arch/powerpc/platforms/powernv/idle.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/arch/powerpc/platforms/powernv/idle.c
> b/arch/powerpc/platforms/powernv/idle.c
> index 19d94d021357..f2e2a6a4c274 100644
> --- a/arch/powerpc/platforms/powernv/idle.c
> +++ b/arch/powerpc/platforms/powernv/idle.c
> @@ -600,6 +600,8 @@ struct p9_sprs {
> u64 iamr;
> u64 amor;
> u64 uamor;
> + u64 dawr0;
> + u64 dawrx0;
> };
>
> static unsigned long power9_idle_stop(unsigned long psscr, bool mmu_on)
> @@ -687,6 +689,10 @@ static unsigned long power9_idle_stop(unsigned long
> psscr, bool mmu_on)
> sprs.iamr = mfspr(SPRN_IAMR);
> sprs.amor = mfspr(SPRN_AMOR);
> sprs.uamor = mfspr(SPRN_UAMOR);
> + if (cpu_has_feature(CPU_FTR_ARCH_31)) {
> + sprs.dawr0 = mfspr(SPRN_DAWR0);
> + sprs.dawrx0 = mfspr(SPRN_DAWRX0);
> + }
>
> srr1 = isa300_idle_stop_mayloss(psscr); /* go idle */
>
> @@ -710,6 +716,10 @@ static unsigned long power9_idle_stop(unsigned long
> psscr, bool mmu_on)
> mtspr(SPRN_IAMR, sprs.iamr);
> mtspr(SPRN_AMOR, sprs.amor);
> mtspr(SPRN_UAMOR, sprs.uamor);
> + if (cpu_has_feature(CPU_FTR_ARCH_31)) {
> + mtspr(SPRN_DAWR0, sprs.dawr0);
> + mtspr(SPRN_DAWRX0, sprs.dawrx0);
> + }
>
> /*
> * Workaround for POWER9 DD2.0, if we lost resources, the ERAT
> --
> 2.25.4
>
>
