Re: [PATCH v3 00/17] KVM: x86/pmu: Add support to enable Guest PEBS via DS

2021-02-01 Thread Xu, Like
On 2021/1/29 10:52, Liuxiangdong (Aven, Cloud Infrastructure Service Product Dept.) wrote: On 2021/1/26 15:08, Xu, Like wrote: On 2021/1/25 22:47, Liuxiangdong (Aven, Cloud Infrastructure Service Product Dept.) wrote: Thanks for replying, On 2021/1/25 10:41, Like Xu wrote: + k...@vger.kerne

Re: [PATCH v3 00/17] KVM: x86/pmu: Add support to enable Guest PEBS via DS

2021-01-28 Thread Liuxiangdong (Aven, Cloud Infrastructure Service Product Dept.)
On 2021/1/26 15:08, Xu, Like wrote: On 2021/1/25 22:47, Liuxiangdong (Aven, Cloud Infrastructure Service Product Dept.) wrote: Thanks for replying, On 2021/1/25 10:41, Like Xu wrote: + k...@vger.kernel.org Hi Liuxiangdong, On 2021/1/22 18:02, Liuxiangdong (Aven, Cloud Infrastructure Servi

Re: [PATCH v3 00/17] KVM: x86/pmu: Add support to enable Guest PEBS via DS

2021-01-26 Thread Xu, Like
On 2021/1/25 22:47, Liuxiangdong (Aven, Cloud Infrastructure Service Product Dept.) wrote: Thanks for replying, On 2021/1/25 10:41, Like Xu wrote: + k...@vger.kernel.org Hi Liuxiangdong, On 2021/1/22 18:02, Liuxiangdong (Aven, Cloud Infrastructure Service Product Dept.) wrote: Hi Like, Som

Re: [PATCH v3 00/17] KVM: x86/pmu: Add support to enable Guest PEBS via DS

2021-01-25 Thread Peter Zijlstra
On Mon, Jan 25, 2021 at 04:08:22PM +0800, Like Xu wrote: > Hi Peter, > > On 2021/1/22 17:56, Peter Zijlstra wrote: > > On Fri, Jan 15, 2021 at 10:51:38AM -0800, Sean Christopherson wrote: > > > On Fri, Jan 15, 2021, Andi Kleen wrote: > > > > > I'm asking about ucode/hardare. Is the "guest pebs bu

Re: [PATCH v3 00/17] KVM: x86/pmu: Add support to enable Guest PEBS via DS

2021-01-25 Thread Peter Zijlstra
On Mon, Jan 25, 2021 at 08:07:06PM +0800, Xu, Like wrote: > So under the premise that counter cross-mapping is allowed, > how can hypercall help fix it ? Hypercall or otherwise exposing the mapping, will let the guest fix it up when it already touches the data. Which avoids the host from having t

Re: [PATCH v3 00/17] KVM: x86/pmu: Add support to enable Guest PEBS via DS

2021-01-25 Thread Xu, Like
On 2021/1/25 20:18, Peter Zijlstra wrote: On Mon, Jan 25, 2021 at 08:07:06PM +0800, Xu, Like wrote: So under the premise that counter cross-mapping is allowed, how can hypercall help fix it ? Hypercall or otherwise exposing the mapping, will let the guest fix it up when it already touches the

Re: [PATCH v3 00/17] KVM: x86/pmu: Add support to enable Guest PEBS via DS

2021-01-25 Thread Liuxiangdong (Aven, Cloud Infrastructure Service Product Dept.)
Thanks for replying, On 2021/1/25 10:41, Like Xu wrote: + k...@vger.kernel.org Hi Liuxiangdong, On 2021/1/22 18:02, Liuxiangdong (Aven, Cloud Infrastructure Service Product Dept.) wrote: Hi Like, Some questions about https://lore.kernel.org/kvm/20210104131542.495413-1-like...@linux.intel.c

Re: [PATCH v3 00/17] KVM: x86/pmu: Add support to enable Guest PEBS via DS

2021-01-25 Thread Xu, Like
On 2021/1/25 19:13, Peter Zijlstra wrote: On Mon, Jan 25, 2021 at 04:08:22PM +0800, Like Xu wrote: Hi Peter, On 2021/1/22 17:56, Peter Zijlstra wrote: On Fri, Jan 15, 2021 at 10:51:38AM -0800, Sean Christopherson wrote: On Fri, Jan 15, 2021, Andi Kleen wrote: I'm asking about ucode/hardare.

Re: [PATCH v3 00/17] KVM: x86/pmu: Add support to enable Guest PEBS via DS

2021-01-25 Thread Like Xu
Hi Peter, On 2021/1/22 17:56, Peter Zijlstra wrote: On Fri, Jan 15, 2021 at 10:51:38AM -0800, Sean Christopherson wrote: On Fri, Jan 15, 2021, Andi Kleen wrote: I'm asking about ucode/hardare. Is the "guest pebs buffer write -> PEBS PMI" guaranteed to be atomic? Of course not. So there's

Re: [PATCH v3 00/17] KVM: x86/pmu: Add support to enable Guest PEBS via DS

2021-01-24 Thread Like Xu
+ k...@vger.kernel.org Hi Liuxiangdong, On 2021/1/22 18:02, Liuxiangdong (Aven, Cloud Infrastructure Service Product Dept.) wrote: Hi Like, Some questions about https://lore.kernel.org/kvm/20210104131542.495413-1-like...@linux.intel.com/

Re: [PATCH v3 00/17] KVM: x86/pmu: Add support to enable Guest PEBS via DS

2021-01-22 Thread Peter Zijlstra
On Fri, Jan 15, 2021 at 10:51:38AM -0800, Sean Christopherson wrote: > On Fri, Jan 15, 2021, Andi Kleen wrote: > > > I'm asking about ucode/hardare. Is the "guest pebs buffer write -> PEBS > > > PMI" > > > guaranteed to be atomic? > > > > Of course not. > > So there's still a window where the g

Re: [PATCH v3 00/17] KVM: x86/pmu: Add support to enable Guest PEBS via DS

2021-01-15 Thread Andi Kleen
On Fri, Jan 15, 2021 at 10:51:38AM -0800, Sean Christopherson wrote: > On Fri, Jan 15, 2021, Andi Kleen wrote: > > > I'm asking about ucode/hardare. Is the "guest pebs buffer write -> PEBS > > > PMI" > > > guaranteed to be atomic? > > > > Of course not. > > So there's still a window where the g

Re: [PATCH v3 00/17] KVM: x86/pmu: Add support to enable Guest PEBS via DS

2021-01-15 Thread Sean Christopherson
On Fri, Jan 15, 2021, Andi Kleen wrote: > > I'm asking about ucode/hardare. Is the "guest pebs buffer write -> PEBS > > PMI" > > guaranteed to be atomic? > > Of course not. So there's still a window where the guest could observe the bad counter index, correct?

Re: [PATCH v3 00/17] KVM: x86/pmu: Add support to enable Guest PEBS via DS

2021-01-15 Thread Andi Kleen
> I'm asking about ucode/hardare. Is the "guest pebs buffer write -> PEBS PMI" > guaranteed to be atomic? Of course not. > > In practice, under what scenarios will guest counters get cross-mapped? And, > how does this support affect guest accuracy? I.e. how bad do things get for > the > guest

Re: [PATCH v3 00/17] KVM: x86/pmu: Add support to enable Guest PEBS via DS

2021-01-15 Thread Sean Christopherson
On Fri, Jan 15, 2021, Xu, Like wrote: > Hi Sean, > > Thanks for your comments ! > > On 2021/1/15 3:10, Sean Christopherson wrote: > > On Mon, Jan 04, 2021, Like Xu wrote: > > > 2) Slow path (part 3, patch 0012-0017) > > > > > > This is when the host assigned physical PMC has a different index >

Re: [PATCH v3 00/17] KVM: x86/pmu: Add support to enable Guest PEBS via DS

2021-01-14 Thread Xu, Like
Hi Sean, Thanks for your comments ! On 2021/1/15 3:10, Sean Christopherson wrote: On Mon, Jan 04, 2021, Like Xu wrote: 2) Slow path (part 3, patch 0012-0017) This is when the host assigned physical PMC has a different index from the virtual PMC (e.g. using physical PMC1 to emulate virtual PMC

Re: [PATCH v3 00/17] KVM: x86/pmu: Add support to enable Guest PEBS via DS

2021-01-14 Thread Sean Christopherson
On Mon, Jan 04, 2021, Like Xu wrote: > 2) Slow path (part 3, patch 0012-0017) > > This is when the host assigned physical PMC has a different index > from the virtual PMC (e.g. using physical PMC1 to emulate virtual PMC0) > In this case, KVM needs to rewrite the PEBS records to change the > applic