linux-kernel - Re: [PATCH 4/4] kvm: Implement PEBS virtualization

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <53A2F6E3.6020703@redhat.com>
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/