Re: [RFC PATCH 01/43] powerpc/64s: Remove WORT SPR from POWER9/10

[Fabiano Rosas <farosas@linux.ibm.com>]

Nicholas Piggin <npiggin@gmail.com> writes:

> This register is not architected and not implemented in POWER9 or 10,
> it just reads back zeroes for compatibility.
>
> -78 cycles (9255) cycles POWER9 virt-mode NULL hcall
>
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>

Reviewed-by: Fabiano Rosas <farosas@linux.ibm.com>

> ---
>  arch/powerpc/kvm/book3s_hv.c          | 3 ---
>  arch/powerpc/platforms/powernv/idle.c | 2 --
>  2 files changed, 5 deletions(-)
>
> diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
> index 9228042bd54f..97f3d6d54b61 100644
> --- a/arch/powerpc/kvm/book3s_hv.c
> +++ b/arch/powerpc/kvm/book3s_hv.c
> @@ -3640,7 +3640,6 @@ static void load_spr_state(struct kvm_vcpu *vcpu)
>  	mtspr(SPRN_EBBHR, vcpu->arch.ebbhr);
>  	mtspr(SPRN_EBBRR, vcpu->arch.ebbrr);
>  	mtspr(SPRN_BESCR, vcpu->arch.bescr);
> -	mtspr(SPRN_WORT, vcpu->arch.wort);
>  	mtspr(SPRN_TIDR, vcpu->arch.tid);
>  	mtspr(SPRN_AMR, vcpu->arch.amr);
>  	mtspr(SPRN_UAMOR, vcpu->arch.uamor);
> @@ -3667,7 +3666,6 @@ static void store_spr_state(struct kvm_vcpu *vcpu)
>  	vcpu->arch.ebbhr = mfspr(SPRN_EBBHR);
>  	vcpu->arch.ebbrr = mfspr(SPRN_EBBRR);
>  	vcpu->arch.bescr = mfspr(SPRN_BESCR);
> -	vcpu->arch.wort = mfspr(SPRN_WORT);
>  	vcpu->arch.tid = mfspr(SPRN_TIDR);
>  	vcpu->arch.amr = mfspr(SPRN_AMR);
>  	vcpu->arch.uamor = mfspr(SPRN_UAMOR);
> @@ -3699,7 +3697,6 @@ static void restore_p9_host_os_sprs(struct kvm_vcpu *vcpu,
>  				    struct p9_host_os_sprs *host_os_sprs)
>  {
>  	mtspr(SPRN_PSPB, 0);
> -	mtspr(SPRN_WORT, 0);
>  	mtspr(SPRN_UAMOR, 0);
>
>  	mtspr(SPRN_DSCR, host_os_sprs->dscr);
> diff --git a/arch/powerpc/platforms/powernv/idle.c b/arch/powerpc/platforms/powernv/idle.c
> index 528a7e0cf83a..180baecad914 100644
> --- a/arch/powerpc/platforms/powernv/idle.c
> +++ b/arch/powerpc/platforms/powernv/idle.c
> @@ -667,7 +667,6 @@ static unsigned long power9_idle_stop(unsigned long psscr)
>  		sprs.purr	= mfspr(SPRN_PURR);
>  		sprs.spurr	= mfspr(SPRN_SPURR);
>  		sprs.dscr	= mfspr(SPRN_DSCR);
> -		sprs.wort	= mfspr(SPRN_WORT);
>  		sprs.ciabr	= mfspr(SPRN_CIABR);
>
>  		sprs.mmcra	= mfspr(SPRN_MMCRA);
> @@ -785,7 +784,6 @@ static unsigned long power9_idle_stop(unsigned long psscr)
>  	mtspr(SPRN_PURR,	sprs.purr);
>  	mtspr(SPRN_SPURR,	sprs.spurr);
>  	mtspr(SPRN_DSCR,	sprs.dscr);
> -	mtspr(SPRN_WORT,	sprs.wort);
>  	mtspr(SPRN_CIABR,	sprs.ciabr);
>
>  	mtspr(SPRN_MMCRA,	sprs.mmcra);