Re: [RFC PATCH 07/43] KVM: PPC: Book3S HV: POWER10 enable HAIL when running radix guests

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

Nicholas Piggin <npiggin@gmail.com> writes:

> HV interrupts may be taken with the MMU enabled when radix guests are
> running. Enable LPCR[HAIL] on ISA v3.1 processors for radix guests.
> Make this depend on the host LPCR[HAIL] being enabled. Currently that is
> always enabled, but having this test means any issue that might require
> LPCR[HAIL] to be disabled in the host will not have to be duplicated in
> KVM.
>
> -1380 cycles on P10 NULL hcall entry+exit
>
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>

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

> ---
>  arch/powerpc/kvm/book3s_hv.c | 29 +++++++++++++++++++++++++----
>  1 file changed, 25 insertions(+), 4 deletions(-)
>
> diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
> index 36e1db48fccf..ed713f49fbd5 100644
> --- a/arch/powerpc/kvm/book3s_hv.c
> +++ b/arch/powerpc/kvm/book3s_hv.c
> @@ -4896,6 +4896,8 @@ static int kvmppc_hv_setup_htab_rma(struct kvm_vcpu *vcpu)
>   */
>  int kvmppc_switch_mmu_to_hpt(struct kvm *kvm)
>  {
> +	unsigned long lpcr, lpcr_mask;
> +
>  	if (nesting_enabled(kvm))
>  		kvmhv_release_all_nested(kvm);
>  	kvmppc_rmap_reset(kvm);
> @@ -4905,8 +4907,13 @@ int kvmppc_switch_mmu_to_hpt(struct kvm *kvm)
>  	kvm->arch.radix = 0;
>  	spin_unlock(&kvm->mmu_lock);
>  	kvmppc_free_radix(kvm);
> -	kvmppc_update_lpcr(kvm, LPCR_VPM1,
> -			   LPCR_VPM1 | LPCR_UPRT | LPCR_GTSE | LPCR_HR);
> +
> +	lpcr = LPCR_VPM1;
> +	lpcr_mask = LPCR_VPM1 | LPCR_UPRT | LPCR_GTSE | LPCR_HR;
> +	if (cpu_has_feature(CPU_FTR_ARCH_31))
> +		lpcr_mask |= LPCR_HAIL;
> +	kvmppc_update_lpcr(kvm, lpcr, lpcr_mask);
> +
>  	return 0;
>  }
>
> @@ -4916,6 +4923,7 @@ int kvmppc_switch_mmu_to_hpt(struct kvm *kvm)
>   */
>  int kvmppc_switch_mmu_to_radix(struct kvm *kvm)
>  {
> +	unsigned long lpcr, lpcr_mask;
>  	int err;
>
>  	err = kvmppc_init_vm_radix(kvm);
> @@ -4927,8 +4935,17 @@ int kvmppc_switch_mmu_to_radix(struct kvm *kvm)
>  	kvm->arch.radix = 1;
>  	spin_unlock(&kvm->mmu_lock);
>  	kvmppc_free_hpt(&kvm->arch.hpt);
> -	kvmppc_update_lpcr(kvm, LPCR_UPRT | LPCR_GTSE | LPCR_HR,
> -			   LPCR_VPM1 | LPCR_UPRT | LPCR_GTSE | LPCR_HR);
> +
> +	lpcr = LPCR_UPRT | LPCR_GTSE | LPCR_HR;
> +	lpcr_mask = LPCR_VPM1 | LPCR_UPRT | LPCR_GTSE | LPCR_HR;
> +	if (cpu_has_feature(CPU_FTR_ARCH_31)) {
> +		lpcr_mask |= LPCR_HAIL;
> +		if (cpu_has_feature(CPU_FTR_HVMODE) &&
> +				(kvm->arch.host_lpcr & LPCR_HAIL))
> +			lpcr |= LPCR_HAIL;
> +	}
> +	kvmppc_update_lpcr(kvm, lpcr, lpcr_mask);
> +
>  	return 0;
>  }
>
> @@ -5092,6 +5109,10 @@ static int kvmppc_core_init_vm_hv(struct kvm *kvm)
>  		kvm->arch.mmu_ready = 1;
>  		lpcr &= ~LPCR_VPM1;
>  		lpcr |= LPCR_UPRT | LPCR_GTSE | LPCR_HR;
> +		if (cpu_has_feature(CPU_FTR_HVMODE) &&
> +		    cpu_has_feature(CPU_FTR_ARCH_31) &&
> +		    (kvm->arch.host_lpcr & LPCR_HAIL))
> +			lpcr |= LPCR_HAIL;
>  		ret = kvmppc_init_vm_radix(kvm);
>  		if (ret) {
>  			kvmppc_free_lpid(kvm->arch.lpid);