Il 10/06/2014 23:06, Marcelo Tosatti ha scritto:
> BTW how about general PMU migration? As far as I can tell there
> is no code to save/restore the state for that currently, right?
Paolo wrote support for it, recently. Paolo?
Yes, on the KVM side all that is needed is to special case MSR reads and
writes that have side effects, for example:
case MSR_CORE_PERF_GLOBAL_STATUS:
if (msr_info->host_initiated) {
pmu->global_status = data;
return 0;
}
break; /* RO MSR */
case MSR_CORE_PERF_GLOBAL_OVF_CTRL:
if (!(data & (pmu->global_ctrl_mask & ~(3ull<<62)))) {
if (!msr_info->host_initiated)
pmu->global_status &= ~data;
pmu->global_ovf_ctrl = data;
return 0;
}
break;
Right now this is only needed for writes.
Userspace then can read/write these MSRs, and add them to the migration
stream. QEMU has code for that.
Paolo
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