This is a rebased and revised version of my patches revising CPU compatiblity mode handling on ppc, last posted in November. Since then, many of the patches have already been merged (some for 2.9, some since). This is what's left.
* There was conceptual confusion about what a compatibility mode means, and how it interacts with the machine type. This cleans that up, clarifying that a compatibility mode (as an externally set option) only makes sense on machine types that don't permit the guest hypervisor privilege (i.e. 'pseries') * It was previously the user's (or management layer's) responsibility to determine compatibility of CPUs on either end for migration. This uses the compatibility modes to check that properly during an incoming migration. This hasn't been extensively tested yet. There are quite a few migration cases to consider, for example: Basic: 1) Boot guest with -cpu host Should go into POWER8 compat mode after CAS Previously would have been raw mode 2) Boot guest with -machine pseries,max-cpu-compat=power7 -cpu host Should go into POWER7 compat mode 3) Boot guest with -cpu host,compat=power7 Should act as (2), but print a warning 4) Boot guest via libvirt with power7 compat mode specified in XML Should act as (3), (2) once we fix libvirt 5) Hack guest to only advertise power7 compatibility, boot with -cpu host Should go into POWER7 compat mode after CAS 6) Hack guest to only advertise real PVRs Should remain in POWER8 raw mode after CAS 7) Hack guest to only advertise real PVRs Boot with -machine pseries,max-cpu-compat=power8 Should fail at CAS time 8) Hack guest to only advertise power7 compatibility, boot with -cpu host Reboot to normal guest Should go to power7 compat mode after CAS of boot 1 Should revert to raw mode on reboot SHould go to power8 compat mode after CAS of boot 2 Migration: 9) Boot guest with qemu-2.6 -machine pseries-2.6 -cpu host Migrate to qemu-2.8 -machine pseries-2.6 -cpu host Should work, end up running in power8 raw mode 10) Boot guest with qemu-2.7 -machine pseries-2.7 -cpu host Migrate to qemu-2.8 -machine pseries-2.7 -cpu host Should work, end up running in power8 raw mode 11) Boot guest with qemu-2.7 -machine pseries-2.7 -cpu host,compat=power7 Migrate to qemu-2.8 -machine pseries-2.7 -cpu host,compat=power7 Should work, be running in POWER7 compat after, but give warning like (3) 12) Boot guest with qemu-2.7 -machine pseries-2.7 -cpu host,compat=power7 Migrate to qemu-2.8 -machine pseries-2.7,max-cpu-compat=power7 -cpu host Should work, be running in POWER7 compat after, no warning 13) Boot to SLOF with qemu-2.6 -machine pseries-2.6 -cpu host Migrate to qemu-2.8 -machine pseries-2.6 -cpu host ? 14) Boot to SLOF with qemu-2.7 -machine pseries-2.7 -cpu host Migrate to qemu-2.8 -machine pseries-2.7 -cpu host ? 15) Boot to SLOF with qemu-2.7 -machine pseries-2.7 -cpu host,compat=power7 Migrate to qemu-2.8 -machine pseries-2.7 -cpu host,compat=power7 ? 16) Boot to SLOF with qemu-2.7 -machine pseries-2.7 -cpu host,compat=power7 Migrate to qemu-2.8 -machine pseries-2.7,max-cpu-compat=power7 -cpu host ? 17) Boot guest with qemu-2.6 -machine pseries-2.6 -cpu host Migrate to qemu-2.7.z -machine pseries-2.6 -cpu host Should work 18) Hack guest to only advertise power7 compatibility, boot with -cpu host Boot with qemu-2.8, migrate to qemu-2.8 Should be in power7 compat mode after CAS on source, and still in power7 compat mode on destination Changes since v3: * Backwards compatible -cpu handling now removes compat= option from options passed on to the cpu, so it doesn't trigger further warnings * Add a migration fix make cpu_synchronize_state() safe in post_load handlers, which in turn fixes a bug in 5/5. * A number of bugfixes and other tweaks suggested by feedback on v2. Changes since RFCv2: * Many patches dropped, since they're already merged * Rebased, fixed conflicts * Restored support for backwards migration (wasn't as complicated as I thought) * Updated final patch's description to more accurately reflect the logic Changes since RFCv1: * Change CAS logic to prefer compatibility modes over raw mode * Simplified by giving up on half-hearted attempts to maintain backwards migration * Folded migration stream changes into a single patch * Removed some preliminary patches which are already merged David Gibson (4): migration: Mark CPU states dirty before incoming migration/loadvm pseries: Move CPU compatibility property to machine pseries: Reset CPU compatibility mode ppc: Rework CPU compatibility testing across migration Greg Kurz (1): qapi: add explicit null to string input and output visitors cpus.c | 9 ++++ hw/ppc/spapr.c | 8 +++- hw/ppc/spapr_cpu_core.c | 62 +++++++++++++++++++++----- hw/ppc/spapr_hcall.c | 8 ++-- include/hw/ppc/spapr.h | 12 +++-- include/sysemu/cpus.h | 1 + include/sysemu/hax.h | 1 + include/sysemu/hw_accel.h | 10 +++++ include/sysemu/kvm.h | 1 + kvm-all.c | 10 +++++ migration/savevm.c | 2 + qapi/string-input-visitor.c | 11 +++++ qapi/string-output-visitor.c | 14 ++++++ target/i386/hax-all.c | 10 +++++ target/ppc/compat.c | 102 +++++++++++++++++++++++++++++++++++++++++++ target/ppc/cpu.h | 5 ++- target/ppc/machine.c | 72 ++++++++++++++++++++++++++++-- target/ppc/translate_init.c | 86 +++++++++++------------------------- 18 files changed, 340 insertions(+), 84 deletions(-) -- 2.9.4