From: Sean Christopherson <seanjc@google.com>
To: Rick P Edgecombe <rick.p.edgecombe@intel.com>
Cc: "jmattson@google.com" <jmattson@google.com>,
Chao Gao <chao.gao@intel.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"vkuznets@redhat.com" <vkuznets@redhat.com>,
Vishal Annapurve <vannapurve@google.com>,
Xiaoyao Li <xiaoyao.li@intel.com>,
Reinette Chatre <reinette.chatre@intel.com>,
Erdem Aktas <erdemaktas@google.com>,
"pbonzini@redhat.com" <pbonzini@redhat.com>,
"mlevitsk@redhat.com" <mlevitsk@redhat.com>,
Isaku Yamahata <isaku.yamahata@intel.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>
Subject: Re: [PATCH V4 0/4] KVM: x86: Make bus clock frequency for vAPIC timer configurable
Date: Wed, 24 Apr 2024 10:23:30 -0700 [thread overview]
Message-ID: <ZilAEhUS-mmgjBK8@google.com> (raw)
In-Reply-To: <26073e608fc450c6c0dcfe1f5cb1590f14c71e96.camel@intel.com>
On Wed, Apr 24, 2024, Rick P Edgecombe wrote:
> On Wed, 2024-04-24 at 09:13 -0700, Sean Christopherson wrote:
> > On Tue, Apr 16, 2024, Rick P Edgecombe wrote:
> > > On Thu, 2024-03-21 at 09:37 -0700, Reinette Chatre wrote:
> > > >
> > > > Summary
> > > > -------
> > > > Add KVM_CAP_X86_APIC_BUS_FREQUENCY capability to configure the APIC
> > > > bus clock frequency for APIC timer emulation.
> > > > Allow KVM_ENABLE_CAPABILITY(KVM_CAP_X86_APIC_BUS_FREQUENCY) to set the
> > > > frequency in nanoseconds. When using this capability, the user space
> > > > VMM should configure CPUID leaf 0x15 to advertise the frequency.
> > >
> > > Looks good to me and...
> > > Tested-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
> > >
> > > The only thing missing is actually integrating it into TDX qemu patches and
> > > testing the resulting TD. I think we are making a fair assumption that the
> > > problem should be resolved based on the analysis, but we have not actually
> > > tested that part. Is that right?
> >
> > Please tell me that Rick is wrong, and that this actually has been tested with
> > a TDX guest. I don't care _who_ tested it, or with what VMM it has been
> > tested, but _someone_ needs to verify that this actually fixes the TDX issue.
>
> It is in the process of getting a TDX test developed (or rather updated).
> Agreed, it requires verification that it fixes the original TDX issue. That is
> why I raised it.
>
> Reinette was working on this internally and some iterations were happening, but
> we are trying to work on the public list as much as possible per your earlier
> comments. So that is why she posted it.
I have no problem posting "early", but Documentation/process/maintainer-kvm-x86.rst
clearly states under Testing that:
If you can't fully test a change, e.g. due to lack of hardware, clearly state
what level of testing you were able to do, e.g. in the cover letter.
I was assuming that this was actually *fully* tested, because nothing suggests
otherwise. And _that_ is a problem, e.g. I was planning on applying this series
for 6.10, which would have made for quite the mess if it turns out that this
doesn't actually solve the TDX problem.
> There was at least some level of TDX integration in the past. I'm not sure what
> exactly was tested, but we are going to re-verify it with the latest everything.
Honest question, is it a big lift to re-test the QEMU+KVM TDX changes, e.g. to
verify this new capability actually does what we hope it does? If testing is a
big lift, what are the pain points? Or perhaps a better question is, is there
anything we (both upstream people, and end users like Google) can do to make
re-testing less awful?
next prev parent reply other threads:[~2024-04-24 17:23 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-21 16:37 [PATCH V4 0/4] KVM: x86: Make bus clock frequency for vAPIC timer configurable Reinette Chatre
2024-03-21 16:37 ` [PATCH V4 1/4] KVM: x86: hyper-v: Calculate APIC bus frequency for Hyper-V Reinette Chatre
2024-04-16 17:07 ` Edgecombe, Rick P
2024-03-21 16:37 ` [PATCH V4 2/4] KVM: x86: Make nsec per APIC bus cycle a VM variable Reinette Chatre
2024-04-16 17:08 ` Edgecombe, Rick P
2024-03-21 16:37 ` [PATCH V4 3/4] KVM: x86: Add a capability to configure bus frequency for APIC timer Reinette Chatre
2024-04-16 17:08 ` Edgecombe, Rick P
2024-04-16 21:28 ` Reinette Chatre
2024-04-17 3:37 ` Xiaoyao Li
2024-03-21 16:37 ` [PATCH V4 4/4] KVM: selftests: Add test for configure of x86 APIC bus frequency Reinette Chatre
2024-04-16 17:09 ` [PATCH V4 0/4] KVM: x86: Make bus clock frequency for vAPIC timer configurable Edgecombe, Rick P
2024-04-24 16:13 ` Sean Christopherson
2024-04-24 16:38 ` Edgecombe, Rick P
2024-04-24 17:23 ` Sean Christopherson [this message]
2024-04-24 18:10 ` Edgecombe, Rick P
2024-04-24 19:57 ` Sean Christopherson
2024-04-24 21:20 ` Reinette Chatre
2024-04-25 16:17 ` Sean Christopherson
2024-04-25 16:39 ` Reinette Chatre
2024-04-24 21:07 ` Reinette Chatre
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