From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-2.mimecast.com ([205.139.110.61]:52713 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729311AbgFVPDR (ORCPT ); Mon, 22 Jun 2020 11:03:17 -0400 Date: Mon, 22 Jun 2020 17:03:03 +0200 From: Cornelia Huck Subject: Re: [PATCH v8 2/2] s390/kvm: diagnose 0x318 sync and reset Message-ID: <20200622170303.5eee22db.cohuck@redhat.com> In-Reply-To: <43967a50-a69c-face-805d-7cc935d3f230@de.ibm.com> References: <20200618222222.23175-1-walling@linux.ibm.com> <20200618222222.23175-3-walling@linux.ibm.com> <20200622122456.781492a8.cohuck@redhat.com> <43967a50-a69c-face-805d-7cc935d3f230@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: Collin Walling , kvm@vger.kernel.org, linux-s390@vger.kernel.org, pbonzini@redhat.com, frankja@linux.ibm.com, david@redhat.com, imbrenda@linux.ibm.com, heiko.carstens@de.ibm.com, gor@linux.ibm.com, thuth@redhat.com On Mon, 22 Jun 2020 16:50:41 +0200 Christian Borntraeger wrote: > On 22.06.20 12:24, Cornelia Huck wrote: > > On Thu, 18 Jun 2020 18:22:22 -0400 > > Collin Walling wrote: > > > >> DIAGNOSE 0x318 (diag318) sets information regarding the environment > >> the VM is running in (Linux, z/VM, etc) and is observed via > >> firmware/service events. > >> > >> This is a privileged s390x instruction that must be intercepted by > >> SIE. Userspace handles the instruction as well as migration. Data > >> is communicated via VCPU register synchronization. > >> > >> The Control Program Name Code (CPNC) is stored in the SIE block. The > >> CPNC along with the Control Program Version Code (CPVC) are stored > >> in the kvm_vcpu_arch struct. > >> > >> The CPNC is shadowed/unshadowed in VSIE. > >> > >> This data is reset on load normal and clear resets. > >> > >> Signed-off-by: Collin Walling > >> --- > >> arch/s390/include/asm/kvm_host.h | 4 +++- > >> arch/s390/include/uapi/asm/kvm.h | 5 ++++- > >> arch/s390/kvm/kvm-s390.c | 11 ++++++++++- > >> arch/s390/kvm/vsie.c | 3 +++ > >> include/uapi/linux/kvm.h | 1 + > >> 5 files changed, 21 insertions(+), 3 deletions(-) > >> > > > > (...) > > > >> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h > >> index 4fdf30316582..35cdb4307904 100644 > >> --- a/include/uapi/linux/kvm.h > >> +++ b/include/uapi/linux/kvm.h > >> @@ -1031,6 +1031,7 @@ struct kvm_ppc_resize_hpt { > >> #define KVM_CAP_PPC_SECURE_GUEST 181 > >> #define KVM_CAP_HALT_POLL 182 > >> #define KVM_CAP_ASYNC_PF_INT 183 > >> +#define KVM_CAP_S390_DIAG318 184 > > > > Do we strictly need this new cap, or would checking against the sync > > regs capabilities be enough? > > We could check the sync_regs valid field to decide about the sync. We do > that for ETOKEN as well and QEMU also uses it in handle_diag_318. > > I think what this is used for is actually to tell the QEMU CPU model > if this is there. And for that the sync_reg validity seems wrong. So better > keep the CAP? > Ok, makes sense.