From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:62978 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726193AbgBRJMB (ORCPT ); Tue, 18 Feb 2020 04:12:01 -0500 Received: from pps.filterd (m0098409.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 01I93uej037007 for ; Tue, 18 Feb 2020 04:12:00 -0500 Received: from e06smtp05.uk.ibm.com (e06smtp05.uk.ibm.com [195.75.94.101]) by mx0a-001b2d01.pphosted.com with ESMTP id 2y6cu2rwp0-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Tue, 18 Feb 2020 04:12:00 -0500 Received: from localhost by e06smtp05.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 18 Feb 2020 09:11:58 -0000 Subject: Re: [PATCH v2 24/42] KVM: s390: protvirt: STSI handling References: <20200214222658.12946-1-borntraeger@de.ibm.com> <20200214222658.12946-25-borntraeger@de.ibm.com> <380a9214-ad1a-42a0-0d7b-49289a20ff37@redhat.com> <148c5d6c-fef4-6cec-af85-8b48c936cc79@redhat.com> From: Christian Borntraeger Date: Tue, 18 Feb 2020 10:11:51 +0100 MIME-Version: 1.0 In-Reply-To: <148c5d6c-fef4-6cec-af85-8b48c936cc79@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Message-Id: Sender: linux-s390-owner@vger.kernel.org List-ID: To: David Hildenbrand , Janosch Frank Cc: KVM , Cornelia Huck , Thomas Huth , Ulrich Weigand , Claudio Imbrenda , linux-s390 , Michael Mueller , Vasily Gorbik , Janosch Frank On 18.02.20 10:08, David Hildenbrand wrote: > On 18.02.20 09:44, Christian Borntraeger wrote: >> >> >> On 18.02.20 09:35, David Hildenbrand wrote: >>> On 14.02.20 23:26, Christian Borntraeger wrote: >>>> From: Janosch Frank >>>> >>>> Save response to sidad and disable address checking for protected >>>> guests. >>>> >>>> Signed-off-by: Janosch Frank >>>> Reviewed-by: Thomas Huth >>>> Reviewed-by: Cornelia Huck >>>> [borntraeger@de.ibm.com: patch merging, splitting, fixing] >>>> Signed-off-by: Christian Borntraeger >>>> --- >>>> arch/s390/kvm/priv.c | 11 ++++++++--- >>>> 1 file changed, 8 insertions(+), 3 deletions(-) >>>> >>>> diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c >>>> index ed52ffa8d5d4..b2de7dc5f58d 100644 >>>> --- a/arch/s390/kvm/priv.c >>>> +++ b/arch/s390/kvm/priv.c >>>> @@ -872,7 +872,7 @@ static int handle_stsi(struct kvm_vcpu *vcpu) >>>> >>>> operand2 = kvm_s390_get_base_disp_s(vcpu, &ar); >>>> >>>> - if (operand2 & 0xfff) >>>> + if (!kvm_s390_pv_is_protected(vcpu->kvm) && (operand2 & 0xfff)) >>>> return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION); >>> >>> Why is that needed? I'd assume the hardware handles this for us and this >>> case can never happen for PV? (IOW, change is not necessary) >> >> Hardware is handling this for us AND we are not allowed to inject a specification >> exception. The ultravisor guards the program checks that we are allowed to inject. >> > > Yeah, but can this ever trigger without the check? AFAIKs, no. So why > add it? It can. the GPRS can contain stale data and so can operand2. > > (rather add a BUG_ON in kvm_s390_inject_program_int() in case we are in > PV mode) > >>> >>>> >>>> switch (fc) { >>>> @@ -893,8 +893,13 @@ static int handle_stsi(struct kvm_vcpu *vcpu) >>>> handle_stsi_3_2_2(vcpu, (void *) mem); >>>> break; >>>> } >>>> - >>>> - rc = write_guest(vcpu, operand2, ar, (void *)mem, PAGE_SIZE); >>>> + if (kvm_s390_pv_is_protected(vcpu->kvm)) { >>>> + memcpy((void *)sida_origin(vcpu->arch.sie_block), (void *)mem, >>>> + PAGE_SIZE); >>>> + rc = 0; >>>> + } else { >>>> + rc = write_guest(vcpu, operand2, ar, (void *)mem, PAGE_SIZE); >>>> + } >>>> if (rc) { >>>> rc = kvm_s390_inject_prog_cond(vcpu, rc); >>>> goto out; >>>> >>> >>> I'd pull the interrupt injection into the else case, makes things clearer. >> >> Well, no. Thhe else case could set rc to 0. > > Huh?! > > if (kvm_s390_pv_is_protected(vcpu->kvm)) { > memcpy((void *)sida_origin(vcpu->arch.sie_block), (void *)mem, > rc = 0; > } else { > rc = write_guest(vcpu, operand2, ar, (void *)mem, PAGE_SIZE); > if (rc) { > rc = kvm_s390_inject_prog_cond(vcpu, rc); > goto out; > } > } > Hmm, I find that one harder to read.