From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0BF8DC4320A for ; Mon, 23 Aug 2021 14:14:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E31F7613AC for ; Mon, 23 Aug 2021 14:14:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229973AbhHWOPG (ORCPT ); Mon, 23 Aug 2021 10:15:06 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:55982 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229743AbhHWOPF (ORCPT ); Mon, 23 Aug 2021 10:15:05 -0400 Received: from pps.filterd (m0098393.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.43/8.16.0.43) with SMTP id 17NE4Ob8052048; Mon, 23 Aug 2021 10:12:51 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=subject : to : cc : references : from : message-id : date : mime-version : in-reply-to : content-type : content-transfer-encoding; s=pp1; bh=JP+rIuvE43NRXIUI5Kb+ogg0I/5LxIIHeZ4VT3NOJSI=; b=HdCP5dSGypid2RyIbAPUCk3pVDYhTdLu+iuqc1SPqEUlq9/SvNF/R0tU6SvZ55CNVBES rE2CCE83XX5njzTOZ2UqRVeBiZjfwprMW6Brh46ayzEXBZJY0FkCgFoxpjX3fNFXKNaO L5kMaEvRafRrAgjXuQ59jfxc1PZsSxUusjIqRQxMjrJ6Aq/4z26WcoeUW+BU9qVUQvUV ATj63FSo1ncLrS47cjKQeUGyfXXDvbf3tCux3hmnc3b4Flq2wDIY6vKG1rVGFwMNdQKH OoOHLDT1nwkL8Rm2aWiD+/Ag1htYp3WmD/H3VYKw9BwAcB+J5fVPbfgIlUyBXxghgKPl JQ== Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com with ESMTP id 3am1eva1g9-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 23 Aug 2021 10:12:50 -0400 Received: from m0098393.ppops.net (m0098393.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.43/8.16.0.43) with SMTP id 17NE4VX8052901; Mon, 23 Aug 2021 10:12:49 -0400 Received: from ppma04ams.nl.ibm.com (63.31.33a9.ip4.static.sl-reverse.com [169.51.49.99]) by mx0a-001b2d01.pphosted.com with ESMTP id 3am1eva1f1-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 23 Aug 2021 10:12:49 -0400 Received: from pps.filterd (ppma04ams.nl.ibm.com [127.0.0.1]) by ppma04ams.nl.ibm.com (8.16.1.2/8.16.1.2) with SMTP id 17NE3PHm014202; Mon, 23 Aug 2021 14:12:47 GMT Received: from b06cxnps4076.portsmouth.uk.ibm.com (d06relay13.portsmouth.uk.ibm.com [9.149.109.198]) by ppma04ams.nl.ibm.com with ESMTP id 3ajs48ucq0-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 23 Aug 2021 14:12:46 +0000 Received: from b06wcsmtp001.portsmouth.uk.ibm.com (b06wcsmtp001.portsmouth.uk.ibm.com [9.149.105.160]) by b06cxnps4076.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 17NEChTt39780754 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 23 Aug 2021 14:12:43 GMT Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 2DE26A4BDF; Mon, 23 Aug 2021 14:12:43 +0000 (GMT) Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id EE119A4BDD; Mon, 23 Aug 2021 14:12:40 +0000 (GMT) Received: from oc7455500831.ibm.com (unknown [9.145.170.214]) by b06wcsmtp001.portsmouth.uk.ibm.com (Postfix) with ESMTP; Mon, 23 Aug 2021 14:12:40 +0000 (GMT) Subject: Re: [PATCH v2 1/2] KVM: Refactor kvm_arch_vcpu_fault() to return a struct page pointer To: David Hildenbrand , Hou Wenlong , kvm@vger.kernel.org Cc: Sean Christopherson , Marc Zyngier , James Morse , Alexandru Elisei , Suzuki K Poulose , Catalin Marinas , Will Deacon , Huacai Chen , Aleksandar Markovic , Thomas Bogendoerfer , Paul Mackerras , Michael Ellerman , Benjamin Herrenschmidt , Janosch Frank , Cornelia Huck , Claudio Imbrenda , Heiko Carstens , Vasily Gorbik , Paolo Bonzini , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org, kvm-ppc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org References: <1c510b24fc1d7cbae8aa4b69c0799ebd32e65b82.1628739116.git.houwenlong93@linux.alibaba.com> <98adbd3c-ec6f-5689-1686-2a8a7909951a@redhat.com> From: Christian Borntraeger Message-ID: Date: Mon, 23 Aug 2021 16:12:40 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: <98adbd3c-ec6f-5689-1686-2a8a7909951a@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: 5V65b4zTLVrYqqCGUcddJc1BLzc-OYWe X-Proofpoint-ORIG-GUID: mhbanuFWoNfFP43Rw2Ff2PaJeTjB43vn X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.790 definitions=2021-08-23_03:2021-08-23,2021-08-23 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 mlxscore=0 mlxlogscore=999 spamscore=0 adultscore=0 lowpriorityscore=0 clxscore=1011 priorityscore=1501 phishscore=0 suspectscore=0 bulkscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2107140000 definitions=main-2108230098 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12.08.21 11:04, David Hildenbrand wrote: > On 12.08.21 06:02, Hou Wenlong wrote: >> From: Sean Christopherson >> >> Refactor kvm_arch_vcpu_fault() to return 'struct page *' instead of >> 'vm_fault_t' to simplify architecture specific implementations that do >> more than return SIGBUS.  Currently this only applies to s390, but a >> future patch will move x86's pio_data handling into x86 where it belongs. >> >> No functional changed intended. >> >> Cc: Hou Wenlong >> Signed-off-by: Sean Christopherson >> Signed-off-by: Hou Wenlong >> --- >>   arch/arm64/kvm/arm.c       |  4 ++-- >>   arch/mips/kvm/mips.c       |  4 ++-- >>   arch/powerpc/kvm/powerpc.c |  4 ++-- >>   arch/s390/kvm/kvm-s390.c   | 12 ++++-------- >>   arch/x86/kvm/x86.c         |  4 ++-- >>   include/linux/kvm_host.h   |  2 +- >>   virt/kvm/kvm_main.c        |  5 ++++- >>   7 files changed, 17 insertions(+), 18 deletions(-) >> >> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c >> index e9a2b8f27792..83f4ffe3e4f2 100644 >> --- a/arch/arm64/kvm/arm.c >> +++ b/arch/arm64/kvm/arm.c >> @@ -161,9 +161,9 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) >>       return ret; >>   } >> -vm_fault_t kvm_arch_vcpu_fault(struct kvm_vcpu *vcpu, struct vm_fault *vmf) >> +struct page *kvm_arch_vcpu_fault(struct kvm_vcpu *vcpu, struct vm_fault *vmf) >>   { >> -    return VM_FAULT_SIGBUS; >> +    return NULL; >>   } >> diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c >> index af9dd029a4e1..ae79874e6fd2 100644 >> --- a/arch/mips/kvm/mips.c >> +++ b/arch/mips/kvm/mips.c >> @@ -1053,9 +1053,9 @@ int kvm_arch_vcpu_ioctl_set_fpu(struct kvm_vcpu *vcpu, struct kvm_fpu *fpu) >>       return -ENOIOCTLCMD; >>   } >> -vm_fault_t kvm_arch_vcpu_fault(struct kvm_vcpu *vcpu, struct vm_fault *vmf) >> +struct page *kvm_arch_vcpu_fault(struct kvm_vcpu *vcpu, struct vm_fault *vmf) >>   { >> -    return VM_FAULT_SIGBUS; >> +    return NULL; >>   } >>   int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) >> diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c >> index be33b5321a76..b9c21f9ab784 100644 >> --- a/arch/powerpc/kvm/powerpc.c >> +++ b/arch/powerpc/kvm/powerpc.c >> @@ -2090,9 +2090,9 @@ long kvm_arch_vcpu_ioctl(struct file *filp, >>       return r; >>   } >> -vm_fault_t kvm_arch_vcpu_fault(struct kvm_vcpu *vcpu, struct vm_fault *vmf) >> +struct page *kvm_arch_vcpu_fault(struct kvm_vcpu *vcpu, struct vm_fault *vmf) >>   { >> -    return VM_FAULT_SIGBUS; >> +    return NULL; >>   } >>   static int kvm_vm_ioctl_get_pvinfo(struct kvm_ppc_pvinfo *pvinfo) >> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c >> index 02574d7b3612..e1b69833e228 100644 >> --- a/arch/s390/kvm/kvm-s390.c >> +++ b/arch/s390/kvm/kvm-s390.c >> @@ -4979,17 +4979,13 @@ long kvm_arch_vcpu_ioctl(struct file *filp, >>       return r; >>   } >> -vm_fault_t kvm_arch_vcpu_fault(struct kvm_vcpu *vcpu, struct vm_fault *vmf) >> +struct page *kvm_arch_vcpu_fault(struct kvm_vcpu *vcpu, struct vm_fault *vmf) >>   { >>   #ifdef CONFIG_KVM_S390_UCONTROL >> -    if ((vmf->pgoff == KVM_S390_SIE_PAGE_OFFSET) >> -         && (kvm_is_ucontrol(vcpu->kvm))) { >> -        vmf->page = virt_to_page(vcpu->arch.sie_block); >> -        get_page(vmf->page); >> -        return 0; >> -    } >> +    if (vmf->pgoff == KVM_S390_SIE_PAGE_OFFSET && kvm_is_ucontrol(vcpu->kvm)) >> +        return virt_to_page(vcpu->arch.sie_block); >>   #endif >> -    return VM_FAULT_SIGBUS; >> +    return NULL; >>   } >>   /* Section: memory related */ >> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c >> index 3cedc7cc132a..1e3bbe5cd33a 100644 >> --- a/arch/x86/kvm/x86.c >> +++ b/arch/x86/kvm/x86.c >> @@ -5347,9 +5347,9 @@ long kvm_arch_vcpu_ioctl(struct file *filp, >>       return r; >>   } >> -vm_fault_t kvm_arch_vcpu_fault(struct kvm_vcpu *vcpu, struct vm_fault *vmf) >> +struct page *kvm_arch_vcpu_fault(struct kvm_vcpu *vcpu, struct vm_fault *vmf) >>   { >> -    return VM_FAULT_SIGBUS; >> +    return NULL; >>   } >>   static int kvm_vm_ioctl_set_tss_addr(struct kvm *kvm, unsigned long addr) >> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h >> index 492d183dd7d0..a949de534722 100644 >> --- a/include/linux/kvm_host.h >> +++ b/include/linux/kvm_host.h >> @@ -995,7 +995,7 @@ long kvm_arch_dev_ioctl(struct file *filp, >>               unsigned int ioctl, unsigned long arg); >>   long kvm_arch_vcpu_ioctl(struct file *filp, >>                unsigned int ioctl, unsigned long arg); >> -vm_fault_t kvm_arch_vcpu_fault(struct kvm_vcpu *vcpu, struct vm_fault *vmf); >> +struct page *kvm_arch_vcpu_fault(struct kvm_vcpu *vcpu, struct vm_fault *vmf); >>   int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext); >> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c >> index 30d322519253..f7d21418971b 100644 >> --- a/virt/kvm/kvm_main.c >> +++ b/virt/kvm/kvm_main.c >> @@ -3448,7 +3448,10 @@ static vm_fault_t kvm_vcpu_fault(struct vm_fault *vmf) >>               &vcpu->dirty_ring, >>               vmf->pgoff - KVM_DIRTY_LOG_PAGE_OFFSET); >>       else >> -        return kvm_arch_vcpu_fault(vcpu, vmf); >> +        page = kvm_arch_vcpu_fault(vcpu, vmf); >> +    if (!page) >> +        return VM_FAULT_SIGBUS; >> + >>       get_page(page); >>       vmf->page = page; >>       return 0; >> > > Reviewed-by: David Hildenbrand > > But at the same time I wonder if we should just get rid of CONFIG_KVM_S390_UCONTROL and consequently kvm_arch_vcpu_fault(). > > > In practice CONFIG_KVM_S390_UCONTROL, is never enabled in any reasonable kernel build and consequently it's never tested; further, exposing the sie_block to user space allows user space to generate random SIE validity intercepts. > > CONFIG_KVM_S390_UCONTROL feels like something that should just be maintained out of tree by someone who really needs to hack deep into hw virtualization for testing purposes etc. I recently talked to the ucontrol users and they will look into selftests.