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    Subject[PATCH v9 00/18] Add AMD SEV guest live migration support
    Date
    From: Ashish Kalra <ashish.kalra@amd.com>

    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 ioctls KVM_{SET,GET}_PAGE_ENC_BITMAP. The ioctl can be used
    by the qemu to get the page encrypted bitmap. Qemu can consult this bitmap
    during the 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 host returns error as part of
    SET_PAGE_ENC_BITMAP ioctl if guest has not enabled live migration.

    A branch containing these patches is available here:
    https://github.com/AMDESE/linux/tree/sev-migration-v9

    [1] https://developer.amd.com/wp-content/resources/55766.PDF

    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 <lkp@intel.com>, 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 <lkp@intel.com>

    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 (7):
    KVM: SVM: Add support for static allocation of unified Page Encryption
    Bitmap.
    KVM: x86: Introduce new KVM_FEATURE_SEV_LIVE_MIGRATION feature &
    Custom MSR.
    EFI: Introduce the new AMD Memory Encryption GUID.
    KVM: x86: Add guest support for detecting and enabling SEV Live
    Migration feature.
    KVM: x86: Mark _bss_decrypted section variables as decrypted in page
    encryption bitmap.
    KVM: x86: Add kexec support for SEV Live Migration.
    KVM: SVM: Enable SEV live migration feature implicitly on Incoming
    VM(s).

    Brijesh Singh (11):
    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
    KVM: X86: Introduce KVM_HC_PAGE_ENC_STATUS hypercall
    KVM: x86: Introduce KVM_GET_PAGE_ENC_BITMAP ioctl
    mm: x86: Invoke hypercall when page encryption status is changed
    KVM: x86: Introduce KVM_SET_PAGE_ENC_BITMAP ioctl

    Ashish Kalra (7):
    KVM: SVM: Add support for static allocation of unified Page Encryption
    Bitmap.
    KVM: x86: Introduce new KVM_FEATURE_SEV_LIVE_MIGRATION feature &
    Custom MSR.
    EFI: Introduce the new AMD Memory Encryption GUID.
    KVM: x86: Add guest support for detecting and enabling SEV Live
    Migration feature.
    KVM: x86: Mark _bss_decrypted section variables as decrypted in page
    encryption bitmap.
    KVM: x86: Add kexec support for SEV Live Migration.
    KVM: SVM: Bypass DBG_DECRYPT API calls for unecrypted guest memory.

    Brijesh Singh (11):
    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
    KVM: X86: Introduce KVM_HC_PAGE_ENC_STATUS hypercall
    KVM: x86: Introduce KVM_GET_PAGE_ENC_BITMAP ioctl
    mm: x86: Invoke hypercall when page encryption status is changed
    KVM: x86: Introduce KVM_SET_PAGE_ENC_BITMAP ioctl

    .../virt/kvm/amd-memory-encryption.rst | 120 +++
    Documentation/virt/kvm/api.rst | 71 ++
    Documentation/virt/kvm/cpuid.rst | 5 +
    Documentation/virt/kvm/hypercalls.rst | 15 +
    Documentation/virt/kvm/msr.rst | 16 +
    arch/x86/include/asm/kvm_host.h | 7 +
    arch/x86/include/asm/kvm_para.h | 12 +
    arch/x86/include/asm/mem_encrypt.h | 11 +
    arch/x86/include/asm/paravirt.h | 10 +
    arch/x86/include/asm/paravirt_types.h | 2 +
    arch/x86/include/uapi/asm/kvm_para.h | 5 +
    arch/x86/kernel/kvm.c | 90 ++
    arch/x86/kernel/kvmclock.c | 12 +
    arch/x86/kernel/paravirt.c | 1 +
    arch/x86/kvm/svm/sev.c | 790 ++++++++++++++++++
    arch/x86/kvm/svm/svm.c | 21 +
    arch/x86/kvm/svm/svm.h | 9 +
    arch/x86/kvm/vmx/vmx.c | 1 +
    arch/x86/kvm/x86.c | 35 +
    arch/x86/mm/mem_encrypt.c | 68 +-
    arch/x86/mm/pat/set_memory.c | 7 +
    include/linux/efi.h | 1 +
    include/linux/psp-sev.h | 8 +-
    include/uapi/linux/kvm.h | 52 ++
    include/uapi/linux/kvm_para.h | 1 +
    25 files changed, 1365 insertions(+), 5 deletions(-)

    --
    2.17.1

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