Re: [PATCH] KVM: PPC: Book3S PR: Set hflag to indicate that POWER9 supports 1T segments

[Michael Ellerman <mpe@ellerman.id.au>]

Suraj Jitindar Singh <sjitindarsingh@gmail.com> writes:

> When booting a kvm-pr guest on a POWER9 machine the following message is
> observed:
> "qemu-system-ppc64: KVM does not support 1TiB segments which guest expects"
>
> This is because the guest is expecting to be able to use 1T segments
> however we don't indicate support for it. This is because we don't set
> the BOOK3S_HFLAG_MULTI_PGSIZE flag in the hflags in kvmppc_set_pvr_pr()
> on POWER9.
>
> POWER9 does indeed have support for 1T segments, so add a case for
> POWER9 to the switch statement to ensure it is set.

If this just checked mmu_has_feature(MMU_FTR_1T_SEGMENT) it would have
been right in this case, and we'd also never have to update it in
future.

Any reason not to?

cheers

> diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c
> index 4efd65d9e828..82840160c606 100644
> --- a/arch/powerpc/kvm/book3s_pr.c
> +++ b/arch/powerpc/kvm/book3s_pr.c
> @@ -587,6 +587,7 @@ void kvmppc_set_pvr_pr(struct kvm_vcpu *vcpu, u32 pvr)
>  	case PVR_POWER8:
>  	case PVR_POWER8E:
>  	case PVR_POWER8NVL:
> +	case PVR_POWER9:
>  		vcpu->arch.hflags |= BOOK3S_HFLAG_MULTI_PGSIZE |
>  			BOOK3S_HFLAG_NEW_TLBIE;
>  		break;
> -- 
> 2.13.6