linux-kernel - Re: [PATCH v13 021/113] KVM: TDX: Make pmu

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Date:   Sun, 28 May 2023 01:26:02 -0700
From:   Isaku Yamahata <isaku.yamahata@...il.com>
To:     Like Xu <like.xu.linux@...il.com>
Cc:     Zhi Wang <zhi.wang.linux@...il.com>, isaku.yamahata@...el.com,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        isaku.yamahata@...il.com, Paolo Bonzini <pbonzini@...hat.com>,
        erdemaktas@...gle.com, Sean Christopherson <seanjc@...gle.com>,
        Sagi Shahar <sagis@...gle.com>,
        David Matlack <dmatlack@...gle.com>,
        Kai Huang <kai.huang@...el.com>
Subject: Re: [PATCH v13 021/113] KVM: TDX: Make pmu_intel.c ignore guest TD
 case

On Wed, Apr 19, 2023 at 04:21:21PM +0800,
Like Xu <like.xu.linux@...il.com> wrote:

> On 2/4/2023 4:50 pm, Zhi Wang wrote:
> > Hi Like:
> > 
> > Would you mind to take a look on this patch? It would be nice to have
> > a r-b also from you. :)
> > 
> > On Sun, 12 Mar 2023 10:55:45 -0700
> > isaku.yamahata@...el.com wrote:
> > 
> > > From: Isaku Yamahata <isaku.yamahata@...el.com>
> > > 
> > > Because TDX KVM doesn't support PMU yet (it's future work of TDX KVM
> > > support as another patch series) and pmu_intel.c touches vmx specific
> 
> It would be nice to have pmu support for tdx-guest from the very beginning.

It's supported in the public github repo.
https://github.com/intel/tdx/tree/kvm-upstream-workaround
As this patch series has 100+ patches, I don't want to bloat this patch more.


> If you guys are more open on the tdx development model, I'd like to help on
> those features.

This mainling list is the place.  


> > > structure in vcpu initialization, as workaround add dummy structure to
> > > struct vcpu_tdx and pmu_intel.c can ignore TDX case.
> 
> If the target is not to provide a workaround, how about other variants:
> 	- struct lbr_desc lbr_desc;
> 	- pebs ds_buffer;
> ?
> 
> We also need tdx selftest to verify the unavailability of these features.
> Also, it would be great to have TDX's "System Profiling Mode" featue back in
> the specification.

I don't think it's productive. Once merging this patch series, we can move on
to TDX PMU support (or whatever still missing feature) as second (or later)
step.
-- 
Isaku Yamahata <isaku.yamahata@...il.com>