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=-23.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, USER_IN_DEF_DKIM_WL autolearn=ham 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 2EEA5C433ED for ; Tue, 6 Apr 2021 01:43:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EF32A613D0 for ; Tue, 6 Apr 2021 01:43:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239410AbhDFBnq (ORCPT ); Mon, 5 Apr 2021 21:43:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45734 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238598AbhDFBnp (ORCPT ); Mon, 5 Apr 2021 21:43:45 -0400 Received: from mail-il1-x130.google.com (mail-il1-x130.google.com [IPv6:2607:f8b0:4864:20::130]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A179FC06174A for ; Mon, 5 Apr 2021 18:43:38 -0700 (PDT) Received: by mail-il1-x130.google.com with SMTP id c15so2906709ilj.1 for ; Mon, 05 Apr 2021 18:43:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=FDVzfft75dAyaBS8qVmmSNpiE2UrCW3GMePF07dthTM=; b=GH3DgAc3bhsZlKkFxAHBnIgf2/i8557AHdarYiFlLThto3WEONP0KMfPHMz8YvjVKS pd6Z0x3Zc8RjGJ5Tb7Gp7Y4qs65lSuL8q62xjld+yp48d0D3HDDEpLx5RfYnKpt8Bs8R dWFCJQ8uI8ZGJYuOBA1dBc218U0JhIoAUr4hALDcnQLFA5j2iHqWygg20IL+iF0dDK9F Q2NATo41mGTSIRGAsT3uyyvsl1mBbwKNm+CvZ5E5FV7MntiztALGonXVSyfVXfVfWUF9 MGTRwVfOorM9ussNDAYn1un5lLtx6i4jC/dyMLRnPsR55EvR+G2B35WHD9HZlUWmY0OE CQNw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=FDVzfft75dAyaBS8qVmmSNpiE2UrCW3GMePF07dthTM=; b=Hu51Gslwvghowf3GJkbSFEUOJHipM/7QILxx3PDM2NfJbPDgqn0lB1IqAHTopx2Ydf 7wLAiYpwhKsXwYRMCZwwsJF0HYKoFnxMkNExr0lGvMHSapFzV4h84h0Acejeb+HA7Go+ f9p372ayoCKFdum14UAxEHdm21/wkwFnpLlegwQUGaoNUWU4C1g3uwfTRXs4AlOF1fmn ReDT8dHpS4hWwB5xQ+JR/UOYdejMG2iTQvx0Vmirql4HAqog3Li1zXZ9GN+rh4UnY6Ml etUEtYnLOJXAD6tJeZWSln+NuOl3MFr+7xH/GIXO4Pggq1T8J2fYeUa5hrfV4iLijBvi mj6A== X-Gm-Message-State: AOAM531OPjwUEQUX6H6Xc5JLT3O/QoqMfT7V6WgjA8CIYSO+3dWAkrKj Ge3h5H9yD/V18Xq2HH5YLQDOrnE0j4Up484ebaFGgz4x0D6sCA== X-Google-Smtp-Source: ABdhPJxfU20mwPziuwaUyaRxkt4TuGH/pQjVi1tTzrlbiA6YXUcF4CFxP+6rMcJWcevuAyymRdvbh9R3hbM/1lUeSSs= X-Received: by 2002:a05:6e02:1887:: with SMTP id o7mr2246755ilu.79.1617673417846; Mon, 05 Apr 2021 18:43:37 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: From: Steve Rutherford Date: Mon, 5 Apr 2021 18:43:01 -0700 Message-ID: Subject: Re: [PATCH v11 00/13] Add AMD SEV guest live migration support To: Ashish Kalra Cc: Paolo Bonzini , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , Joerg Roedel , Borislav Petkov , Tom Lendacky , X86 ML , KVM list , LKML , Sean Christopherson , Venu Busireddy , Brijesh Singh Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 5, 2021 at 7:20 AM Ashish Kalra wrote: > > From: Ashish Kalra > > The series add support for AMD SEV guest live migration commands. To protect the > confidentiality of an SEV protected guest memory while in transit we need to > use the SEV commands defined in SEV API spec [1]. > > SEV guest VMs have the concept of private and shared memory. Private memory > is encrypted with the guest-specific key, while shared memory may be encrypted > with hypervisor key. The commands provided by the SEV FW are meant to be used > for the private memory only. The patch series introduces a new hypercall. > The guest OS can use this hypercall to notify the page encryption status. > If the page is encrypted with guest specific-key then we use SEV command during > the migration. If page is not encrypted then fallback to default. > > The patch adds new KVM_EXIT_DMA_SHARE/KVM_EXIT_DMA_UNSHARE hypercall to > userspace exit functionality as a common interface from the guest back to the > VMM and passing on the guest shared/unencrypted page information to the > userspace VMM/Qemu. Qemu can consult this information during migration to know > whether the page is encrypted. > > This section descibes how the SEV live migration feature is negotiated > between the host and guest, the host indicates this feature support via > KVM_FEATURE_CPUID. The guest firmware (OVMF) detects this feature and > sets a UEFI enviroment variable indicating OVMF support for live > migration, the guest kernel also detects the host support for this > feature via cpuid and in case of an EFI boot verifies if OVMF also > supports this feature by getting the UEFI enviroment variable and if it > set then enables live migration feature on host by writing to a custom > MSR, if not booted under EFI, then it simply enables the feature by > again writing to the custom MSR. The MSR is also handled by the > userspace VMM/Qemu. > > A branch containing these patches is available here: > https://github.com/AMDESE/linux/tree/sev-migration-v11 > > [1] https://developer.amd.com/wp-content/resources/55766.PDF > > Changes since v10: > - Adds new KVM_EXIT_DMA_SHARE/KVM_EXIT_DMA_UNSHARE hypercall to > userspace exit functionality as a common interface from the guest back to the > KVM and passing on the guest shared/unencrypted region information to the > userspace VMM/Qemu. KVM/host kernel does not maintain the guest shared > memory regions information anymore. > - Remove implicit enabling of SEV live migration feature for an SEV > guest, now this is explicitly in control of the userspace VMM/Qemu. > - Custom MSR handling is also now moved into userspace VMM/Qemu. > - As KVM does not maintain the guest shared memory region information > anymore, sev_dbg_crypt() cannot bypass unencrypted guest memory > regions without support from userspace VMM/Qemu. > > Changes since v9: > - Transitioning from page encryption bitmap to the shared pages list > to keep track of guest's shared/unencrypted memory regions. > - Move back to marking the complete _bss_decrypted section as > decrypted in the shared pages list. > - Invoke a new function check_kvm_sev_migration() via kvm_init_platform() > for guest to query for host-side support for SEV live migration > and to enable the SEV live migration feature, to avoid > #ifdefs in code > - Rename MSR_KVM_SEV_LIVE_MIG_EN to MSR_KVM_SEV_LIVE_MIGRATION. > - Invoke a new function handle_unencrypted_region() from > sev_dbg_crypt() to bypass unencrypted guest memory regions. > > Changes since v8: > - Rebasing to kvm next branch. > - Fixed and added comments as per review feedback on v8 patches. > - Removed implicitly enabling live migration for incoming VMs in > in KVM_SET_PAGE_ENC_BITMAP, it is now done via KVM_SET_MSR ioctl. > - Adds support for bypassing unencrypted guest memory regions for > DBG_DECRYPT API calls, guest memory region encryption status in > sev_dbg_decrypt() is referenced using the page encryption bitmap. > > Changes since v7: > - Removed the hypervisor specific hypercall/paravirt callback for > SEV live migration and moved back to calling kvm_sev_hypercall3 > directly. > - Fix build errors as > Reported-by: kbuild test robot , specifically fixed > build error when CONFIG_HYPERVISOR_GUEST=y and > CONFIG_AMD_MEM_ENCRYPT=n. > - Implicitly enabled live migration for incoming VM(s) to handle > A->B->C->... VM migrations. > - Fixed Documentation as per comments on v6 patches. > - Fixed error return path in sev_send_update_data() as per comments > on v6 patches. > > Changes since v6: > - Rebasing to mainline and refactoring to the new split SVM > infrastructre. > - Move to static allocation of the unified Page Encryption bitmap > instead of the dynamic resizing of the bitmap, the static allocation > is done implicitly by extending kvm_arch_commit_memory_region() callack > to add svm specific x86_ops which can read the userspace provided memory > region/memslots and calculate the amount of guest RAM managed by the KVM > and grow the bitmap. > - Fixed KVM_SET_PAGE_ENC_BITMAP ioctl to set the whole bitmap instead > of simply clearing specific bits. > - Removed KVM_PAGE_ENC_BITMAP_RESET ioctl, which is now performed using > KVM_SET_PAGE_ENC_BITMAP. > - Extended guest support for enabling Live Migration feature by adding a > check for UEFI environment variable indicating OVMF support for Live > Migration feature and additionally checking for KVM capability for the > same feature. If not booted under EFI, then we simply check for KVM > capability. > - Add hypervisor specific hypercall for SEV live migration by adding > a new paravirt callback as part of x86_hyper_runtime. > (x86 hypervisor specific runtime callbacks) > - Moving MSR handling for MSR_KVM_SEV_LIVE_MIG_EN into svm/sev code > and adding check for SEV live migration enabled by guest in the > KVM_GET_PAGE_ENC_BITMAP ioctl. > - Instead of the complete __bss_decrypted section, only specific variables > such as hv_clock_boot and wall_clock are marked as decrypted in the > page encryption bitmap > > Changes since v5: > - Fix build errors as > Reported-by: kbuild test robot > > Changes since v4: > - Host support has been added to extend KVM capabilities/feature bits to > include a new KVM_FEATURE_SEV_LIVE_MIGRATION, which the guest can > query for host-side support for SEV live migration and a new custom MSR > MSR_KVM_SEV_LIVE_MIG_EN is added for guest to enable the SEV live > migration feature. > - Ensure that _bss_decrypted section is marked as decrypted in the > page encryption bitmap. > - Fixing KVM_GET_PAGE_ENC_BITMAP ioctl to return the correct bitmap > as per the number of pages being requested by the user. Ensure that > we only copy bmap->num_pages bytes in the userspace buffer, if > bmap->num_pages is not byte aligned we read the trailing bits > from the userspace and copy those bits as is. This fixes guest > page(s) corruption issues observed after migration completion. > - Add kexec support for SEV Live Migration to reset the host's > page encryption bitmap related to kernel specific page encryption > status settings before we load a new kernel by kexec. We cannot > reset the complete page encryption bitmap here as we need to > retain the UEFI/OVMF firmware specific settings. > > Changes since v3: > - Rebasing to mainline and testing. > - Adding a new KVM_PAGE_ENC_BITMAP_RESET ioctl, which resets the > page encryption bitmap on a guest reboot event. > - Adding a more reliable sanity check for GPA range being passed to > the hypercall to ensure that guest MMIO ranges are also marked > in the page encryption bitmap. > > Changes since v2: > - reset the page encryption bitmap on vcpu reboot > > Changes since v1: > - Add support to share the page encryption between the source and target > machine. > - Fix review feedbacks from Tom Lendacky. > - Add check to limit the session blob length. > - Update KVM_GET_PAGE_ENC_BITMAP icotl to use the base_gfn instead of > the memory slot when querying the bitmap. > > Ashish Kalra (5): > KVM: X86: Introduce KVM_HC_PAGE_ENC_STATUS hypercall > KVM: x86: Introduce new KVM_FEATURE_SEV_LIVE_MIGRATION feature & > Custom MSR. > EFI: Introduce the new AMD Memory Encryption GUID. > x86/kvm: Add guest support for detecting and enabling SEV Live > Migration feature. > x86/kvm: Add kexec support for SEV Live Migration. > > Brijesh Singh (8): > KVM: SVM: Add KVM_SEV SEND_START command > KVM: SVM: Add KVM_SEND_UPDATE_DATA command > KVM: SVM: Add KVM_SEV_SEND_FINISH command > KVM: SVM: Add support for KVM_SEV_RECEIVE_START command > KVM: SVM: Add KVM_SEV_RECEIVE_UPDATE_DATA command > KVM: SVM: Add KVM_SEV_RECEIVE_FINISH command > KVM: x86: Add AMD SEV specific Hypercall3 > mm: x86: Invoke hypercall when page encryption status is changed > > .../virt/kvm/amd-memory-encryption.rst | 120 ++++ > Documentation/virt/kvm/api.rst | 18 + > Documentation/virt/kvm/cpuid.rst | 5 + > Documentation/virt/kvm/hypercalls.rst | 15 + > Documentation/virt/kvm/msr.rst | 12 + > arch/x86/include/asm/kvm_host.h | 2 + > arch/x86/include/asm/kvm_para.h | 12 + > arch/x86/include/asm/mem_encrypt.h | 8 + > arch/x86/include/asm/paravirt.h | 10 + > arch/x86/include/asm/paravirt_types.h | 2 + > arch/x86/include/uapi/asm/kvm_para.h | 4 + > arch/x86/kernel/kvm.c | 76 +++ > arch/x86/kernel/paravirt.c | 1 + > arch/x86/kvm/cpuid.c | 3 +- > arch/x86/kvm/svm/sev.c | 514 ++++++++++++++++++ > arch/x86/kvm/svm/svm.c | 24 + > arch/x86/kvm/svm/svm.h | 2 + > arch/x86/kvm/vmx/vmx.c | 1 + > arch/x86/kvm/x86.c | 12 + > arch/x86/mm/mem_encrypt.c | 98 +++- > arch/x86/mm/pat/set_memory.c | 7 + > include/linux/efi.h | 1 + > include/linux/psp-sev.h | 8 +- > include/uapi/linux/kvm.h | 47 ++ > include/uapi/linux/kvm_para.h | 1 + > 25 files changed, 997 insertions(+), 6 deletions(-) > > -- > 2.17.1 > Overall, these patches are in pretty good shape. I have some nits, but otherwise these seem good to go.