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Date: Thu, 19 Jun 2014 16:42:43 +0200 From: Paolo Bonzini <pbonzini@...hat.com> To: Marcelo Tosatti <mtosatti@...hat.com>, Andi Kleen <ak@...ux.intel.com> CC: Andi Kleen <andi@...stfloor.org>, peterz@...radead.org, gleb@...nel.org, eranian@...gle.com, kvm@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH 4/4] kvm: Implement PEBS virtualization 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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