Re: [RFC PATCH 00/26] Confidential guest live migration
On 02/03/21 21:47, Dov Murik wrote: In order to allow OVMF to run the migration helper in parallel to the guest OS, we introduce the notion of auxiliary vcpus, which are usable for OVMF but are hidden from the guest OS. These might have other future uses for in-guest operations/agents. Hi Dov, I think the helper approach to migration in general is great, but I'm not sure I agree with the concept of auxiliary vCPUs. I would rather have a completely separate VM file descriptor that does not even go through the regular KVM run loop. Patches were posted recently to the KVM mailing list to create secondary VMs sharing the encryption context (ASID) with a primary VM. When starting the VM, the firmware would proceed with attestation as usual, detect it was running as a migration helper VM during the SEC phase, and divert execution to the migration helper instead of continuing with PEI. The main advantage would be that the migration VM would not have to share the address space with the primary VM. This would allow migrating encrypted RAM areas that are not visible to the primary VM, for example PCI BARs (those areas would be a problem for the kernel migration bitmap though; I'll remark on that separately on Ashish's KVM series). The VM would not even have an interrupt controller, so that HLT exits to the host when it's done processing the mailbox. This would make it much simpler to audit both the QEMU and the firmware sides. Paolo In the target VM we need the migration handler running to receive incoming RAM pages; to achieve that, we boot the VM into OVMF with a special fw_cfg value that causes OVMF to not boot the guest OS; we then allow QEMU to receive an incoming migration by issuing a new start-migrate-incoming QMP command. The confidential RAM migration requires checking whether a given guest RAM page is encrypted or not. This is currently achieved using AMD's patches which track the encryption status of guest pages in KVM, using hypercalls from OVMF and guest Linux to report changes of such status. The QEMU side of these patches is included as the first two patches in this series. The concrete implementation of this page encryption tracking is currently in flux in the KVM mailing list, but the underlying implementation doesn't affect our confidential RAM migration as long as it can check whether a given guest address is encrypted. List of patches in this series: 1-2: reposting AMD encrypted page bitmap support. 3-11: introduce the notion of auxiliary vcpus. 12-21: introduce the migration specifics. 22-23: fix devices issues when loading state into a live VM 24: introduce the start-migrate-incoming QMP command to switch the target into accepting the incoming migration. 25: remove SEV migration blocker 26: add documentation Brijesh Singh (1): kvm: add support to sync the page encryption state bitmap Dov Murik (21): linux-headers: Add definitions of KVM page encryption bitmap ioctls machine: Add auxcpus=N suboption to -smp hw/boards: Add aux flag to CPUArchId hw/i386: Mark auxiliary vcpus in possible_cpus cpu: Add boolean aux field to CPUState hw/i386: Set CPUState.aux=true for auxiliary vcpus softmmu: Don't sync aux vcpus in pre_loadvm softmmu: Add cpu_synchronize_without_aux_post_init migration: Add helpers to save confidential RAM migration: Add helpers to load confidential RAM migration: Introduce gpa_inside_migration_helper_shared_area migration: Save confidential guest RAM using migration helper migration: Load confidential guest RAM using migration helper migration: Stop VM after loading confidential RAM migration: Don't sync vcpus when migrating confidential guests migration: When starting target, don't sync auxiliary vcpus hw/isa/lpc_ich9: Allow updating an already-running VM target/i386: Re-sync kvm-clock after confidential guest migration migration: Add start-migrate-incoming QMP command target/i386: SEV: Allow migration unless there are no aux vcpus docs: Add confidential guest live migration documentation Tobin Feldman-Fitzthum (4): hw/acpi: Don't include auxiliary vcpus in ACPI tables softmmu: Add pause_all_vcpus_except_aux migration: Stop non-aux vcpus before copying the last pages migration: Call migration handler cleanup routines docs/confidential-guest-live-migration.rst | 142 docs/confidential-guest-support.txt| 5 + docs/index.rst | 1 + qapi/migration.json| 26 +++ include/exec/ram_addr.h| 197 include/exec/ramblock.h| 3 + include/exec/ramlist.h | 3 +- include/hw/boards.h| 3 + include/hw/core/cpu.h | 2 + include/hw/i386/x86.h | 2 +- include/sysemu/cpus.h | 2 + linux-headers/linux/kvm.h
Re: [RFC PATCH 00/26] Confidential guest live migration
The errors reported below on patch 02/26 are due to rebasing an older patch from AMD. I didn't want to make any changes to the code (except make it compile and run correctly) because this feature (encrypted pages bitmap) is still work-in-progress (in KVM and QEMU). -Dov On 02/03/2021 23:24, no-re...@patchew.org wrote: > Patchew URL: > https://patchew.org/QEMU/20210302204822.81901-1-dovmu...@linux.vnet.ibm.com/ > > > > Hi, > > This series seems to have some coding style problems. See output below for > more information: > > Type: series > Message-id: 20210302204822.81901-1-dovmu...@linux.vnet.ibm.com > Subject: [RFC PATCH 00/26] Confidential guest live migration > > === TEST SCRIPT BEGIN === > #!/bin/bash > git rev-parse base > /dev/null || exit 0 > git config --local diff.renamelimit 0 > git config --local diff.renames True > git config --local diff.algorithm histogram > ./scripts/checkpatch.pl --mailback base.. > === TEST SCRIPT END === > > Updating 3c8cf5a9c21ff8782164d1def7f44bd888713384 > From https://github.com/patchew-project/qemu > - [tag update] patchew/20210302175524.1290840-1-berra...@redhat.com -> > patchew/20210302175524.1290840-1-berra...@redhat.com > * [new tag] > patchew/20210302204822.81901-1-dovmu...@linux.vnet.ibm.com -> > patchew/20210302204822.81901-1-dovmu...@linux.vnet.ibm.com > Switched to a new branch 'test' > f283a35 docs: Add confidential guest live migration documentation > 08f3c3b target/i386: SEV: Allow migration unless there are no aux vcpus > 99d1efb migration: Add start-migrate-incoming QMP command > 6ca0894 target/i386: Re-sync kvm-clock after confidential guest migration > 47e02a0 hw/isa/lpc_ich9: Allow updating an already-running VM > af25d7b migration: Call migration handler cleanup routines > 48db1fb migration: When starting target, don't sync auxiliary vcpus > 5eb9336 migration: Don't sync vcpus when migrating confidential guests > af9b2fa migration: Stop non-aux vcpus before copying the last pages > 2789368 migration: Stop VM after loading confidential RAM > 4692252 migration: Load confidential guest RAM using migration helper > e041f58 migration: Save confidential guest RAM using migration helper > 328a888 migration: Introduce gpa_inside_migration_helper_shared_area > b71be10 migration: Add helpers to load confidential RAM > 32bdb2e migration: Add helpers to save confidential RAM > 8d2fccb softmmu: Add pause_all_vcpus_except_aux > ed10484 softmmu: Add cpu_synchronize_without_aux_post_init > e68df04 softmmu: Don't sync aux vcpus in pre_loadvm > 17bfe19 hw/i386: Set CPUState.aux=true for auxiliary vcpus > 808eb76 cpu: Add boolean aux field to CPUState > 34d94b2 hw/acpi: Don't include auxiliary vcpus in ACPI tables > 2e9bc24 hw/i386: Mark auxiliary vcpus in possible_cpus > 3d07b10 hw/boards: Add aux flag to CPUArchId > 0e07c01 machine: Add auxcpus=N suboption to -smp > 49124f3 kvm: add support to sync the page encryption state bitmap > 47f202b linux-headers: Add definitions of KVM page encryption bitmap ioctls > > === OUTPUT BEGIN === > 1/26 Checking commit 47f202b0bc8c (linux-headers: Add definitions of KVM page > encryption bitmap ioctls) > 2/26 Checking commit 49124f3bf03f (kvm: add support to sync the page > encryption state bitmap) > ERROR: use qemu_real_host_page_size instead of getpagesize() > #51: FILE: accel/kvm/kvm-all.c:615: > +ram_addr_t pages = int128_get64(section->size) / getpagesize(); > > ERROR: use qemu_real_host_page_size instead of getpagesize() > #171: FILE: include/exec/ram_addr.h:398: > +unsigned long hpratio = getpagesize() / TARGET_PAGE_SIZE; > > WARNING: line over 80 characters > #197: FILE: include/exec/ram_addr.h:424: > +qatomic_xchg([DIRTY_MEMORY_ENCRYPTED][idx][offset], > temp); > > total: 2 errors, 1 warnings, 340 lines checked > > Patch 2/26 has style problems, please review. If any of these errors > are false positives report them to the maintainer, see > CHECKPATCH in MAINTAINERS. > > 3/26 Checking commit 0e07c0168e00 (machine: Add auxcpus=N suboption to -smp) > 4/26 Checking commit 3d07b103b36f (hw/boards: Add aux flag to CPUArchId) > 5/26 Checking commit 2e9bc24b9064 (hw/i386: Mark auxiliary vcpus in > possible_cpus) > 6/26 Checking commit 34d94b2baa07 (hw/acpi: Don't include auxiliary vcpus in > ACPI tables) > 7/26 Checking commit 808eb7693543 (cpu: Add boolean aux field to CPUState) > 8/26 Checking commit 17bfe1902081 (hw/i386: Set CPUState.aux=true for > auxiliary vcpus) > WARNING: line over 80 characters > #26: FILE: hw/i386/x86.c:104: > +void x86_cpu_new(X86MachineState *x86ms, int64_t apic_id, bool aux, Error > **errp) > > WARNING: line over 80 characters > #
Re: [RFC PATCH 00/26] Confidential guest live migration
Patchew URL: https://patchew.org/QEMU/20210302204822.81901-1-dovmu...@linux.vnet.ibm.com/ Hi, This series seems to have some coding style problems. See output below for more information: Type: series Message-id: 20210302204822.81901-1-dovmu...@linux.vnet.ibm.com Subject: [RFC PATCH 00/26] Confidential guest live migration === TEST SCRIPT BEGIN === #!/bin/bash git rev-parse base > /dev/null || exit 0 git config --local diff.renamelimit 0 git config --local diff.renames True git config --local diff.algorithm histogram ./scripts/checkpatch.pl --mailback base.. === TEST SCRIPT END === Updating 3c8cf5a9c21ff8782164d1def7f44bd888713384 From https://github.com/patchew-project/qemu - [tag update] patchew/20210302175524.1290840-1-berra...@redhat.com -> patchew/20210302175524.1290840-1-berra...@redhat.com * [new tag] patchew/20210302204822.81901-1-dovmu...@linux.vnet.ibm.com -> patchew/20210302204822.81901-1-dovmu...@linux.vnet.ibm.com Switched to a new branch 'test' f283a35 docs: Add confidential guest live migration documentation 08f3c3b target/i386: SEV: Allow migration unless there are no aux vcpus 99d1efb migration: Add start-migrate-incoming QMP command 6ca0894 target/i386: Re-sync kvm-clock after confidential guest migration 47e02a0 hw/isa/lpc_ich9: Allow updating an already-running VM af25d7b migration: Call migration handler cleanup routines 48db1fb migration: When starting target, don't sync auxiliary vcpus 5eb9336 migration: Don't sync vcpus when migrating confidential guests af9b2fa migration: Stop non-aux vcpus before copying the last pages 2789368 migration: Stop VM after loading confidential RAM 4692252 migration: Load confidential guest RAM using migration helper e041f58 migration: Save confidential guest RAM using migration helper 328a888 migration: Introduce gpa_inside_migration_helper_shared_area b71be10 migration: Add helpers to load confidential RAM 32bdb2e migration: Add helpers to save confidential RAM 8d2fccb softmmu: Add pause_all_vcpus_except_aux ed10484 softmmu: Add cpu_synchronize_without_aux_post_init e68df04 softmmu: Don't sync aux vcpus in pre_loadvm 17bfe19 hw/i386: Set CPUState.aux=true for auxiliary vcpus 808eb76 cpu: Add boolean aux field to CPUState 34d94b2 hw/acpi: Don't include auxiliary vcpus in ACPI tables 2e9bc24 hw/i386: Mark auxiliary vcpus in possible_cpus 3d07b10 hw/boards: Add aux flag to CPUArchId 0e07c01 machine: Add auxcpus=N suboption to -smp 49124f3 kvm: add support to sync the page encryption state bitmap 47f202b linux-headers: Add definitions of KVM page encryption bitmap ioctls === OUTPUT BEGIN === 1/26 Checking commit 47f202b0bc8c (linux-headers: Add definitions of KVM page encryption bitmap ioctls) 2/26 Checking commit 49124f3bf03f (kvm: add support to sync the page encryption state bitmap) ERROR: use qemu_real_host_page_size instead of getpagesize() #51: FILE: accel/kvm/kvm-all.c:615: +ram_addr_t pages = int128_get64(section->size) / getpagesize(); ERROR: use qemu_real_host_page_size instead of getpagesize() #171: FILE: include/exec/ram_addr.h:398: +unsigned long hpratio = getpagesize() / TARGET_PAGE_SIZE; WARNING: line over 80 characters #197: FILE: include/exec/ram_addr.h:424: +qatomic_xchg([DIRTY_MEMORY_ENCRYPTED][idx][offset], temp); total: 2 errors, 1 warnings, 340 lines checked Patch 2/26 has style problems, please review. If any of these errors are false positives report them to the maintainer, see CHECKPATCH in MAINTAINERS. 3/26 Checking commit 0e07c0168e00 (machine: Add auxcpus=N suboption to -smp) 4/26 Checking commit 3d07b103b36f (hw/boards: Add aux flag to CPUArchId) 5/26 Checking commit 2e9bc24b9064 (hw/i386: Mark auxiliary vcpus in possible_cpus) 6/26 Checking commit 34d94b2baa07 (hw/acpi: Don't include auxiliary vcpus in ACPI tables) 7/26 Checking commit 808eb7693543 (cpu: Add boolean aux field to CPUState) 8/26 Checking commit 17bfe1902081 (hw/i386: Set CPUState.aux=true for auxiliary vcpus) WARNING: line over 80 characters #26: FILE: hw/i386/x86.c:104: +void x86_cpu_new(X86MachineState *x86ms, int64_t apic_id, bool aux, Error **errp) WARNING: line over 80 characters #58: FILE: include/hw/i386/x86.h:88: +void x86_cpu_new(X86MachineState *pcms, int64_t apic_id, bool aux, Error **errp); total: 0 errors, 2 warnings, 34 lines checked Patch 8/26 has style problems, please review. If any of these errors are false positives report them to the maintainer, see CHECKPATCH in MAINTAINERS. 9/26 Checking commit e68df046c12e (softmmu: Don't sync aux vcpus in pre_loadvm) 10/26 Checking commit ed104842e25d (softmmu: Add cpu_synchronize_without_aux_post_init) 11/26 Checking commit 8d2fccbd9cf9 (softmmu: Add pause_all_vcpus_except_aux) WARNING: Block comments use a leading /* on a separate line #88: FILE: softmmu/cpus.c:614: +/* We need to drop the replay_lock so any vCPU threads woken up total: 0 errors, 1 warnings, 78 lines checked Patch 11/26 has style problems, please rev
[RFC PATCH 00/26] Confidential guest live migration
This is an RFC series for fast migration of confidential guests using an in-guest migration helper that lives in OVMF. QEMU VM live migration needs to read source VM's RAM and write it in the target VM; this mechanism doesn't work when the guest memory is encrypted or QEMU is prevented from reading it in another way. In order to support live migration in such scenarios, we introduce an in-guest migration helper which can securely extract RAM content from the guest in order to send it to the target. The migration helper is implemented as part of the VM's firmware in OVMF. We've implemented and tested this on AMD SEV, but expect most of the processes can be used with other technologies that prevent direct access of hypervisor to the guest's memory. Specifically, we don't use SEV's PSP migration commands (SEV_SEND_START, SEV_RECEIVE_START, etc) at all. Corresponding RFC patches for OVMF have been posted by my colleague Tobin Feldman-Fitzthum on edk2-devel. Those include the crux of the migration helper: a mailbox protocol over a shared memory page which allows communication between QEMU and the migration helper. In the source VM this is used to read a page and encrypt it for transport; in the target it is used to decrypt the incoming page and storing the content in the correct address in the guest memory. All encryption and decryption operations occur inside the trusted context in the VM, and therefore the VM's memory plaintext content is never accessible to the hosts participating in the migration. In order to allow OVMF to run the migration helper in parallel to the guest OS, we introduce the notion of auxiliary vcpus, which are usable for OVMF but are hidden from the guest OS. These might have other future uses for in-guest operations/agents. In the target VM we need the migration handler running to receive incoming RAM pages; to achieve that, we boot the VM into OVMF with a special fw_cfg value that causes OVMF to not boot the guest OS; we then allow QEMU to receive an incoming migration by issuing a new start-migrate-incoming QMP command. The confidential RAM migration requires checking whether a given guest RAM page is encrypted or not. This is currently achieved using AMD's patches which track the encryption status of guest pages in KVM, using hypercalls from OVMF and guest Linux to report changes of such status. The QEMU side of these patches is included as the first two patches in this series. The concrete implementation of this page encryption tracking is currently in flux in the KVM mailing list, but the underlying implementation doesn't affect our confidential RAM migration as long as it can check whether a given guest address is encrypted. List of patches in this series: 1-2: reposting AMD encrypted page bitmap support. 3-11: introduce the notion of auxiliary vcpus. 12-21: introduce the migration specifics. 22-23: fix devices issues when loading state into a live VM 24: introduce the start-migrate-incoming QMP command to switch the target into accepting the incoming migration. 25: remove SEV migration blocker 26: add documentation Brijesh Singh (1): kvm: add support to sync the page encryption state bitmap Dov Murik (21): linux-headers: Add definitions of KVM page encryption bitmap ioctls machine: Add auxcpus=N suboption to -smp hw/boards: Add aux flag to CPUArchId hw/i386: Mark auxiliary vcpus in possible_cpus cpu: Add boolean aux field to CPUState hw/i386: Set CPUState.aux=true for auxiliary vcpus softmmu: Don't sync aux vcpus in pre_loadvm softmmu: Add cpu_synchronize_without_aux_post_init migration: Add helpers to save confidential RAM migration: Add helpers to load confidential RAM migration: Introduce gpa_inside_migration_helper_shared_area migration: Save confidential guest RAM using migration helper migration: Load confidential guest RAM using migration helper migration: Stop VM after loading confidential RAM migration: Don't sync vcpus when migrating confidential guests migration: When starting target, don't sync auxiliary vcpus hw/isa/lpc_ich9: Allow updating an already-running VM target/i386: Re-sync kvm-clock after confidential guest migration migration: Add start-migrate-incoming QMP command target/i386: SEV: Allow migration unless there are no aux vcpus docs: Add confidential guest live migration documentation Tobin Feldman-Fitzthum (4): hw/acpi: Don't include auxiliary vcpus in ACPI tables softmmu: Add pause_all_vcpus_except_aux migration: Stop non-aux vcpus before copying the last pages migration: Call migration handler cleanup routines docs/confidential-guest-live-migration.rst | 142 docs/confidential-guest-support.txt| 5 + docs/index.rst | 1 + qapi/migration.json| 26 +++ include/exec/ram_addr.h| 197 include/exec/ramblock.h| 3 + include/exec/ramlist.h
