AMD SEV encrypts the memory of VMs and because this encryption is done using an address tweak, the hypervisor will not be able to simply copy ciphertext between machines to migrate a VM. Instead the AMD SEV Key Management API provides a set of functions which the hypervisor can use to package a guest encrypted pages for migration, while maintaining the confidentiality provided by AMD SEV.
The patch series add the support required in Qemu to perform the SEV guest live migration. Before initiating the live migration a user should use newly added 'migrate-set-sev-info' command to pass the target machines certificate chain. See the docs/amd-memory-encryption.txt for further details. The patch series depends on kernel patches available here: https://marc.info/?l=kvm&m=156278967226011&w=2 The complete tree with patch is available at: https://github.com/codomania/qemu/tree/sev-migration-v3 Known Issues: - failed to reboot the guest after migration. - The top 10 lines of the vga buffer is sent as encrypted and because of that we get a garage on destination. I am still debugging it. Changes since v2: - Remove direct kvm_memcrpt calls from migration. - Add MemoryEcryptionOps in machine which will be used by migration instead of kvm_memcrypt calls. - drop the RAM_SAVE_FLAG_PAGE_ENCRYPTED_BITMAP. Now the RAM_SAVE_FLAG_ENCRYPTED_PAGE can be used for sending bitmap as well as guest RAM encrypted pages - add some bound checks on incoming data - drop migrate-sev-set-info object - extend the migrate-parameters to include the SEV specific certificate fields. - multiple fixes based on the review comments from Dave Changes since v1: - use the dirty log sync APIs to also sync the page encryption bitmap when SEV is active. Brijesh Singh (14): doc: update AMD SEV API spec web link doc: update AMD SEV to include Live migration flow migration.json: add AMD SEV specific migration parameters linux-headers: update kernel header to include SEV migration commands hw/machine: add helper to query the memory encryption state hw/machine: introduce MachineMemoryEncryptionOps for encrypted VMs target/i386: sev: provide callback to setup outgoing context target/i386: sev: do not create launch context for an incoming guest target/i386: sev: add support to encrypt the outgoing page target/i386: sev: add support to load incoming encrypted page migration: add support to migrate page encryption bitmap kvm: add support to sync the page encryption state bitmap migration/ram: add support to send encrypted pages target/i386: sev: remove migration blocker accel/kvm/kvm-all.c | 91 ++++++ accel/kvm/sev-stub.c | 28 ++ docs/amd-memory-encryption.txt | 48 ++- hw/core/machine.c | 5 + include/exec/ram_addr.h | 199 +++++++++++++ include/exec/ramlist.h | 3 +- include/hw/boards.h | 25 ++ include/sysemu/sev.h | 11 + linux-headers/linux/kvm.h | 53 ++++ migration/migration.c | 61 ++++ migration/ram.c | 148 +++++++++- monitor/hmp-cmds.c | 18 ++ qapi/migration.json | 41 ++- target/i386/sev.c | 513 ++++++++++++++++++++++++++++++++- target/i386/sev_i386.h | 8 + target/i386/trace-events | 8 + 16 files changed, 1234 insertions(+), 26 deletions(-) -- 2.17.1
