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Peter Anvin" , Joerg Roedel , Borislav Petkov , Tom Lendacky , X86 ML , KVM list , LKML , David Rientjes , Andy Lutomirski , Brijesh Singh Subject: Re: [PATCH v6 12/14] KVM: x86: Introduce KVM_PAGE_ENC_BITMAP_RESET ioctl Message-ID: <20200408015221.GB27608@ashkalra_ubuntu_server> References: <9e959ee134ad77f62c9881b8c54cd27e35055072.1585548051.git.ashish.kalra@amd.com> <20200403214559.GB28747@ashkalra_ubuntu_server> <65c09963-2027-22c1-e04d-4c8c3658b2c3@oracle.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) X-ClientProxiedBy: DM5PR21CA0052.namprd21.prod.outlook.com (2603:10b6:3:129::14) To DM5PR12MB1386.namprd12.prod.outlook.com (2603:10b6:3:77::9) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from ashkalra_ubuntu_server (165.204.77.1) by DM5PR21CA0052.namprd21.prod.outlook.com (2603:10b6:3:129::14) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.2921.9 via Frontend Transport; Wed, 8 Apr 2020 01:52:23 +0000 X-Originating-IP: [165.204.77.1] X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-HT: Tenant X-MS-Office365-Filtering-Correlation-Id: da63d478-5d18-4726-6e42-08d7db5f7b88 X-MS-TrafficTypeDiagnostic: DM5PR12MB1481:|DM5PR12MB1481: X-MS-Exchange-Transport-Forked: True X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:6430; X-Forefront-PRVS: 0367A50BB1 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:DM5PR12MB1386.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFTY:;SFS:(10009020)(4636009)(346002)(376002)(396003)(366004)(136003)(39860400002)(33656002)(53546011)(66946007)(66476007)(66556008)(2906002)(316002)(1076003)(478600001)(4326008)(33716001)(54906003)(9686003)(6916009)(55016002)(7416002)(81166006)(26005)(8676002)(81156014)(86362001)(5660300002)(186003)(16526019)(52116002)(44832011)(956004)(6496006)(8936002);DIR:OUT;SFP:1101; Received-SPF: None (protection.outlook.com: amd.com does not designate permitted sender hosts) X-MS-Exchange-SenderADCheck: 1 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: rUiW+YAu/Czpc6N6+Qi8jeqaH+9TLhx+bokwgZVJGocEQ8eXNFkDN44qbZEGIXVkWqmh4C2QyGmBv3Xpof2UaqpFZAZtAyXhZ3UbZxfSdWQflYkNXHikm6opI6KeR7jdUwUUoCq1tnGvdp6MGBMt+en/OinZllKUqsxsX4+yw8gv2mHDYdmLvChgEsPteEvTBjH9qO0r367VTUCVw5B5iRJ+hdNi+Sstwk+n69X1wep67YfvoeJAIkLX1lPNxIUdeNksdt9EiaW+Y5aQHrHQv+OQk1+9VOLNEEC4+BaykEvt2yRdk27D/FfPSW0Tc5uLKhHqYNKB+k+yzS2w0vADtYGEwvfa8nZlY8wJZYF/vhdxDGyowzNnJPEhUR0xoNoW8OPEl3JXDU9yVD+223NXQW577civyz9iqgeTPeh65F7JOm3Cr6YwYtzQ/6V2cHOB X-MS-Exchange-AntiSpam-MessageData: ZI6cZrLi3VAh0jqddn1U7XgzTftUNwFq0Pm4IuVqYxuC04q5a6IzqRx/5nZOE0mH3ssn9HP7+e1W5i6jsmaZpKLo1zJ/0pK7aQIeb54W42L1PQ61PsRDqjfT55Z/PbJTHhCwaZaqL4SHwsnJEy8U0w== X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-Network-Message-Id: da63d478-5d18-4726-6e42-08d7db5f7b88 X-MS-Exchange-CrossTenant-OriginalArrivalTime: 08 Apr 2020 01:52:23.9098 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 8AU918nwZ9eyFUTrxogmeLdTpy1sKEkxaF1LoJpj53p3EIthYi+xX5HLvGgoPn7tEgT5lxuLepR+sZ08fTsr4A== X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM5PR12MB1481 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Steve, On Tue, Apr 07, 2020 at 06:25:51PM -0700, Steve Rutherford wrote: > On Mon, Apr 6, 2020 at 11:53 AM Krish Sadhukhan > wrote: > > > > > > On 4/3/20 2:45 PM, Ashish Kalra wrote: > > > On Fri, Apr 03, 2020 at 02:14:23PM -0700, Krish Sadhukhan wrote: > > >> On 3/29/20 11:23 PM, Ashish Kalra wrote: > > >>> From: Ashish Kalra > > >>> > > >>> This ioctl can be used by the application to reset the page > > >>> encryption bitmap managed by the KVM driver. A typical usage > > >>> for this ioctl is on VM reboot, on reboot, we must reinitialize > > >>> the bitmap. > > >>> > > >>> Signed-off-by: Ashish Kalra > > >>> --- > > >>> Documentation/virt/kvm/api.rst | 13 +++++++++++++ > > >>> arch/x86/include/asm/kvm_host.h | 1 + > > >>> arch/x86/kvm/svm.c | 16 ++++++++++++++++ > > >>> arch/x86/kvm/x86.c | 6 ++++++ > > >>> include/uapi/linux/kvm.h | 1 + > > >>> 5 files changed, 37 insertions(+) > > >>> > > >>> diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst > > >>> index 4d1004a154f6..a11326ccc51d 100644 > > >>> --- a/Documentation/virt/kvm/api.rst > > >>> +++ b/Documentation/virt/kvm/api.rst > > >>> @@ -4698,6 +4698,19 @@ During the guest live migration the outgoing guest exports its page encryption > > >>> bitmap, the KVM_SET_PAGE_ENC_BITMAP can be used to build the page encryption > > >>> bitmap for an incoming guest. > > >>> +4.127 KVM_PAGE_ENC_BITMAP_RESET (vm ioctl) > > >>> +----------------------------------------- > > >>> + > > >>> +:Capability: basic > > >>> +:Architectures: x86 > > >>> +:Type: vm ioctl > > >>> +:Parameters: none > > >>> +:Returns: 0 on success, -1 on error > > >>> + > > >>> +The KVM_PAGE_ENC_BITMAP_RESET is used to reset the guest's page encryption > > >>> +bitmap during guest reboot and this is only done on the guest's boot vCPU. > > >>> + > > >>> + > > >>> 5. The kvm_run structure > > >>> ======================== > > >>> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > > >>> index d30f770aaaea..a96ef6338cd2 100644 > > >>> --- a/arch/x86/include/asm/kvm_host.h > > >>> +++ b/arch/x86/include/asm/kvm_host.h > > >>> @@ -1273,6 +1273,7 @@ struct kvm_x86_ops { > > >>> struct kvm_page_enc_bitmap *bmap); > > >>> int (*set_page_enc_bitmap)(struct kvm *kvm, > > >>> struct kvm_page_enc_bitmap *bmap); > > >>> + int (*reset_page_enc_bitmap)(struct kvm *kvm); > > >>> }; > > >>> struct kvm_arch_async_pf { > > >>> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c > > >>> index 313343a43045..c99b0207a443 100644 > > >>> --- a/arch/x86/kvm/svm.c > > >>> +++ b/arch/x86/kvm/svm.c > > >>> @@ -7797,6 +7797,21 @@ static int svm_set_page_enc_bitmap(struct kvm *kvm, > > >>> return ret; > > >>> } > > >>> +static int svm_reset_page_enc_bitmap(struct kvm *kvm) > > >>> +{ > > >>> + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; > > >>> + > > >>> + if (!sev_guest(kvm)) > > >>> + return -ENOTTY; > > >>> + > > >>> + mutex_lock(&kvm->lock); > > >>> + /* by default all pages should be marked encrypted */ > > >>> + if (sev->page_enc_bmap_size) > > >>> + bitmap_fill(sev->page_enc_bmap, sev->page_enc_bmap_size); > > >>> + mutex_unlock(&kvm->lock); > > >>> + return 0; > > >>> +} > > >>> + > > >>> static int svm_mem_enc_op(struct kvm *kvm, void __user *argp) > > >>> { > > >>> struct kvm_sev_cmd sev_cmd; > > >>> @@ -8203,6 +8218,7 @@ static struct kvm_x86_ops svm_x86_ops __ro_after_init = { > > >>> .page_enc_status_hc = svm_page_enc_status_hc, > > >>> .get_page_enc_bitmap = svm_get_page_enc_bitmap, > > >>> .set_page_enc_bitmap = svm_set_page_enc_bitmap, > > >>> + .reset_page_enc_bitmap = svm_reset_page_enc_bitmap, > > >> > > >> We don't need to initialize the intel ops to NULL ? It's not initialized in > > >> the previous patch either. > > >> > > >>> }; > > > This struct is declared as "static storage", so won't the non-initialized > > > members be 0 ? > > > > > > Correct. Although, I see that 'nested_enable_evmcs' is explicitly > > initialized. We should maintain the convention, perhaps. > > > > > > > >>> static int __init svm_init(void) > > >>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > > >>> index 05e953b2ec61..2127ed937f53 100644 > > >>> --- a/arch/x86/kvm/x86.c > > >>> +++ b/arch/x86/kvm/x86.c > > >>> @@ -5250,6 +5250,12 @@ long kvm_arch_vm_ioctl(struct file *filp, > > >>> r = kvm_x86_ops->set_page_enc_bitmap(kvm, &bitmap); > > >>> break; > > >>> } > > >>> + case KVM_PAGE_ENC_BITMAP_RESET: { > > >>> + r = -ENOTTY; > > >>> + if (kvm_x86_ops->reset_page_enc_bitmap) > > >>> + r = kvm_x86_ops->reset_page_enc_bitmap(kvm); > > >>> + break; > > >>> + } > > >>> default: > > >>> r = -ENOTTY; > > >>> } > > >>> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h > > >>> index b4b01d47e568..0884a581fc37 100644 > > >>> --- a/include/uapi/linux/kvm.h > > >>> +++ b/include/uapi/linux/kvm.h > > >>> @@ -1490,6 +1490,7 @@ struct kvm_enc_region { > > >>> #define KVM_GET_PAGE_ENC_BITMAP _IOW(KVMIO, 0xc5, struct kvm_page_enc_bitmap) > > >>> #define KVM_SET_PAGE_ENC_BITMAP _IOW(KVMIO, 0xc6, struct kvm_page_enc_bitmap) > > >>> +#define KVM_PAGE_ENC_BITMAP_RESET _IO(KVMIO, 0xc7) > > >>> /* Secure Encrypted Virtualization command */ > > >>> enum sev_cmd_id { > > >> Reviewed-by: Krish Sadhukhan > > > Doesn't this overlap with the set ioctl? Yes, obviously, you have to > copy the new value down and do a bit more work, but I don't think > resetting the bitmap is going to be the bottleneck on reboot. Seems > excessive to add another ioctl for this. The set ioctl is generally available/provided for the incoming VM to setup the page encryption bitmap, this reset ioctl is meant for the source VM as a simple interface to reset the whole page encryption bitmap. Thanks, Ashish