On 06/24/2014 07:45 PM, Marcelo Tosatti wrote:
On Sun, Jun 22, 2014 at 09:02:25PM +0200, Andi Kleen wrote:
First, it's not sufficient to pin the debug store area, you also
have to pin the guest page tables that are used to map the debug
store. But even if you do that, as soon as the guest fork
On Sun, Jun 22, 2014 at 09:02:25PM +0200, Andi Kleen wrote:
> > First, it's not sufficient to pin the debug store area, you also
> > have to pin the guest page tables that are used to map the debug
> > store. But even if you do that, as soon as the guest fork()s, it
> > will create a new pgd which
> First, it's not sufficient to pin the debug store area, you also
> have to pin the guest page tables that are used to map the debug
> store. But even if you do that, as soon as the guest fork()s, it
> will create a new pgd which the host will be free to swap out. The
> processor can then attemp
On 05/30/2014 04:12 AM, Andi Kleen wrote:
From: Andi Kleen
PEBS (Precise Event Bases Sampling) profiling is very powerful,
allowing improved sampling precision and much additional information,
like address or TSX abort profiling. cycles:p and :pp uses PEBS.
This patch enables PEBS profiling i
> > Userspace then can read/write these MSRs, and add them to the migration
> > stream. QEMU has code for that.
>
> Thanks. The PEBS setup always redoes its state, can be arbitarily often
> redone.
>
> So the only change needed would be to add the MSRs to some list in qemu?
Yes, and also adding
> Userspace then can read/write these MSRs, and add them to the migration
> stream. QEMU has code for that.
Thanks. The PEBS setup always redoes its state, can be arbitarily often redone.
So the only change needed would be to add the MSRs to some list in qemu?
-Andi
--
a...@linux.intel.com --
Il 02/06/2014 21:57, Andi Kleen ha scritto:
> It would be a bigger concern if we expected virtual PMU migration to
> work, but I think it would be nice to update kvm_pmu_cpuid_update() to
> notice the presence/absence of the new CPUID bits, and then store that
> into per-VM kvm_pmu->pebs_allowed
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
On Tue, Jun 10, 2014 at 12:22:07PM -0700, Andi Kleen wrote:
> On Tue, Jun 10, 2014 at 03:04:48PM -0300, Marcelo Tosatti wrote:
> > On Thu, May 29, 2014 at 06:12:07PM -0700, Andi Kleen wrote:
> > > {
> > > struct kvm_pmu *pmu = &vcpu->arch.pmu;
> > > @@ -407,6 +551,20 @@ int kvm_pmu_set_msr(struc
On Tue, Jun 10, 2014 at 03:04:48PM -0300, Marcelo Tosatti wrote:
> On Thu, May 29, 2014 at 06:12:07PM -0700, Andi Kleen wrote:
> > {
> > struct kvm_pmu *pmu = &vcpu->arch.pmu;
> > @@ -407,6 +551,20 @@ int kvm_pmu_set_msr(struct kvm_vcpu *vcpu, struct
> > msr_data *msr_info)
> >
On Thu, May 29, 2014 at 06:12:07PM -0700, Andi Kleen wrote:
> {
> struct kvm_pmu *pmu = &vcpu->arch.pmu;
> @@ -407,6 +551,20 @@ int kvm_pmu_set_msr(struct kvm_vcpu *vcpu, struct
> msr_data *msr_info)
> return 0;
> }
> break;
> + case MSR
> It seems to me that with this patch, there is no way to expose a
> PMU-without-PEBS to the guest if the host has PEBS.
If you clear the CPUIDs then noone would ilikely access it.
But fair enough, I'll add extra checks for CPUID.
> It would be a bigger concern if we expected virtual PMU migrati
On Mon, Jun 02, 2014 at 07:45:35PM +0300, Gleb Natapov wrote:
> On Fri, May 30, 2014 at 09:24:24AM -0700, Andi Kleen wrote:
> > > > To avoid any problems with guest pages being swapped by the host we
> > > > pin the pages when the PEBS buffer is setup, by intercepting
> > > > that MSR.
> > > It wil
On Thu, May 29, 2014 at 6:12 PM, Andi Kleen wrote:
> From: Andi Kleen
>
> PEBS (Precise Event Bases Sampling) profiling is very powerful,
> allowing improved sampling precision and much additional information,
> like address or TSX abort profiling. cycles:p and :pp uses PEBS.
>
> This patch enabl
BTW I found some more problems in the v1 version.
> > > With EPT it is less likely to happen (but still possible IIRC depending
> > > on memory
> > > pressure and how much memory shadow paging code is allowed to use),
> > > without EPT
> > > it will happen for sure.
> >
> > Don't care about th
On Fri, May 30, 2014 at 09:24:24AM -0700, Andi Kleen wrote:
> > > To avoid any problems with guest pages being swapped by the host we
> > > pin the pages when the PEBS buffer is setup, by intercepting
> > > that MSR.
> > It will avoid guest page to be swapped, but shadow paging code may still
> >
> > To avoid any problems with guest pages being swapped by the host we
> > pin the pages when the PEBS buffer is setup, by intercepting
> > that MSR.
> It will avoid guest page to be swapped, but shadow paging code may still drop
> shadow PT pages that build a mapping from DS virtual address to th
On Thu, May 29, 2014 at 06:12:07PM -0700, Andi Kleen wrote:
> From: Andi Kleen
>
> PEBS (Precise Event Bases Sampling) profiling is very powerful,
> allowing improved sampling precision and much additional information,
> like address or TSX abort profiling. cycles:p and :pp uses PEBS.
>
> This p
From: Andi Kleen
PEBS (Precise Event Bases Sampling) profiling is very powerful,
allowing improved sampling precision and much additional information,
like address or TSX abort profiling. cycles:p and :pp uses PEBS.
This patch enables PEBS profiling in KVM guests.
PEBS writes profiling records
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