From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:58334 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729309AbgBYMdF (ORCPT ); Tue, 25 Feb 2020 07:33:05 -0500 Date: Tue, 25 Feb 2020 13:32:52 +0100 From: Cornelia Huck Subject: Re: [PATCH v4 24/36] KVM: s390: protvirt: Do only reset registers that are accessible Message-ID: <20200225133252.479644ea.cohuck@redhat.com> In-Reply-To: <20200224114107.4646-25-borntraeger@de.ibm.com> References: <20200224114107.4646-1-borntraeger@de.ibm.com> <20200224114107.4646-25-borntraeger@de.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-s390-owner@vger.kernel.org List-ID: To: Christian Borntraeger Cc: Janosch Frank , KVM , David Hildenbrand , Thomas Huth , Ulrich Weigand , Claudio Imbrenda , linux-s390 , Michael Mueller , Vasily Gorbik , Janosch Frank On Mon, 24 Feb 2020 06:40:55 -0500 Christian Borntraeger wrote: > From: Janosch Frank > > For protected VMs the hypervisor can not access guest breaking event > address, program parameter, bpbc and todpr. Do not reset those fields > as the control block does not provide access to these fields. > > Signed-off-by: Janosch Frank > Reviewed-by: David Hildenbrand > [borntraeger@de.ibm.com: patch merging, splitting, fixing] > Signed-off-by: Christian Borntraeger > --- > arch/s390/kvm/kvm-s390.c | 10 ++++++---- > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c > index 6ab4c88f2e1d..c734e89235f9 100644 > --- a/arch/s390/kvm/kvm-s390.c > +++ b/arch/s390/kvm/kvm-s390.c > @@ -3499,14 +3499,16 @@ static void kvm_arch_vcpu_ioctl_initial_reset(struct kvm_vcpu *vcpu) > kvm_s390_set_prefix(vcpu, 0); > kvm_s390_set_cpu_timer(vcpu, 0); > vcpu->arch.sie_block->ckc = 0; > - vcpu->arch.sie_block->todpr = 0; > memset(vcpu->arch.sie_block->gcr, 0, sizeof(vcpu->arch.sie_block->gcr)); > vcpu->arch.sie_block->gcr[0] = CR0_INITIAL_MASK; > vcpu->arch.sie_block->gcr[14] = CR14_INITIAL_MASK; > vcpu->run->s.regs.fpc = 0; > - vcpu->arch.sie_block->gbea = 1; > - vcpu->arch.sie_block->pp = 0; > - vcpu->arch.sie_block->fpf &= ~FPF_BPBC; > + if (!kvm_s390_pv_cpu_is_protected(vcpu)) { > + vcpu->arch.sie_block->gbea = 1; > + vcpu->arch.sie_block->pp = 0; > + vcpu->arch.sie_block->fpf &= ~FPF_BPBC; > + vcpu->arch.sie_block->todpr = 0; What happens if we do change those values? Is it just ignored or will we get an exception on the next SIE entry? > + } > } > > static void kvm_arch_vcpu_ioctl_clear_reset(struct kvm_vcpu *vcpu)