On 30/10/16 22:12, David Gibson wrote: > Server-class POWER CPUs can be put into several compatibility modes. These > can be specified on the command line, or negotiated by the guest during > boot. > > Currently we don't migrate the compatibility mode, which means after a > migration the guest will revert to running with whatever compatibility > mode (or none) specified on the command line. > > With the limited range of CPUs currently used, this doesn't usually cause > a problem, but it could. Fix this by adding the compatibility mode (if > set) to the migration stream. > > Signed-off-by: David Gibson <da...@gibson.dropbear.id.au> > --- > target-ppc/machine.c | 34 ++++++++++++++++++++++++++++++++++ > 1 file changed, 34 insertions(+) > > diff --git a/target-ppc/machine.c b/target-ppc/machine.c > index 4820f22..5d87ff6 100644 > --- a/target-ppc/machine.c > +++ b/target-ppc/machine.c > @@ -9,6 +9,7 @@ > #include "mmu-hash64.h" > #include "migration/cpu.h" > #include "exec/exec-all.h" > +#include "qapi/error.h" > > static int cpu_load_old(QEMUFile *f, void *opaque, int version_id) > { > @@ -176,6 +177,20 @@ static int cpu_post_load(void *opaque, int version_id) > * software has to take care of running QEMU in a compatible mode. > */ > env->spr[SPR_PVR] = env->spr_cb[SPR_PVR].default_value; > + > +#if defined(TARGET_PPC64) > + if (cpu->compat_pvr) { > + Error *local_err = NULL; > + > + ppc_set_compat(cpu, cpu->compat_pvr, &local_err); > + if (local_err) { > + error_report_err(local_err); > + error_free(local_err); > + return -1; > + } > + } > +#endif > + > env->lr = env->spr[SPR_LR]; > env->ctr = env->spr[SPR_CTR]; > cpu_write_xer(env, env->spr[SPR_XER]); > @@ -528,6 +543,24 @@ static const VMStateDescription vmstate_tlbmas = { > } > }; > > +static bool compat_needed(void *opaque) > +{ > + PowerPCCPU *cpu = opaque; > + > + return cpu->compat_pvr != 0;
Finally got to trying how this affects migration :) This breaks migration to QEMU <=2.7, and it should not at least when both source and destination are running with -cpu host,compat=power7. > +} > + > +static const VMStateDescription vmstate_compat = { > + .name = "cpu/compat", > + .version_id = 1, > + .minimum_version_id = 1, > + .needed = compat_needed, > + .fields = (VMStateField[]) { > + VMSTATE_UINT32(compat_pvr, PowerPCCPU), > + VMSTATE_END_OF_LIST() > + } > +}; > + > const VMStateDescription vmstate_ppc_cpu = { > .name = "cpu", > .version_id = 5, > @@ -580,6 +613,7 @@ const VMStateDescription vmstate_ppc_cpu = { > &vmstate_tlb6xx, > &vmstate_tlbemb, > &vmstate_tlbmas, > + &vmstate_compat, > NULL > } > }; > -- Alexey