Hi Sean, On 4/24/2024 10:23 AM, Sean Christopherson wrote: > 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@xxxxxxxxx> >>>> >>>> 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 one vote for the capability name to rather be KVM_CAP_X86_APIC_BUS_CYCLES_NS [1] I'd be happy to resubmit with the name changed but after reading your statement above it is not clear to me what name is preferred: KVM_CAP_X86_APIC_BUS_FREQUENCY as used in this series that seem to meet your approval or KVM_CAP_X86_APIC_BUS_CYCLES_NS. Please let me know what you prefer. Thank you. Reinette [1] https://lore.kernel.org/lkml/1e26b405-f382-45f4-9dd5-3ea5db68302a@xxxxxxxxx/
