On Thu, Nov 09, 2023 at 07:55:45AM -0800, Sean Christopherson <seanjc@xxxxxxxxxx> wrote: > On Wed, Nov 08, 2023, Isaku Yamahata wrote: > > On Tue, Nov 07, 2023 at 12:03:35PM -0800, Jim Mattson <jmattson@xxxxxxxxxx> wrote: > > > I think I know the answer, but do you have any tests for this new feature? > > > > If you mean kvm kselftest, no. > > I have > > - TDX patched qemu > > - kvm-unit-tests: test_apic_timer_one_shot() @ kvm-unit-tests/x86/apic.c > > TDX version is found at https://github.com/intel/kvm-unit-tests-tdx > > We're planning to upstream the changes for TDX > > > > How far do we want to go? > > - Run kvm-unit-tests with TDX. What I have right now. > > - kvm-unit-tests: extend qemu for default VM case and update > > test_apic_timer_one_host() > > Hrm, I'm not sure that we can do a whole lot for test_apic_timer_one_shot(). Or > rather, I'm not sure it's worth the effort to try and add coverage beyond what's > already there. > > As for TDX, *if* we extend KUT, please don't make it depend on TDX. Very few people > have access to TDX platforms and anything CoCo is pretty much guaranteed to be harder > to debug. It made the test cases work with TDX + UEFI bios by adjusting command line to invoke qemu. And skip unsuitable tests. Maybe we can generalize the way to twist qemu command line. > > - kselftest > > Right now kvm kselftest doesn't have test cases even for in-kernel IRQCHIP > > creation. > > Selftests always create an in-kernel APIC. And I think selftests are perfectly > suited to complement the coverage provided by KUT. Specifically, the failure > scenario for this is that KVM emulates at 1Ghz whereas TDX advertises 25Mhz, i.e. > the test case we want is to verify that the APIC timer doesn't expire early. > > There's no need for any APIC infrastructure, e.g. a selftest doesn't even need to > handle an interrupt. Get the TSC frequency from KVM, program up an arbitrary APIC > bus clock frequency, set TMICT such that it expires waaaay in the future, and then > verify that the APIC timer counts reasonably close to the programmed frequency. > E.g. if the test sets the bus clock to 25Mhz, the "drift" due to KVM counting at > 1Ghz should be super obvious. Oh, only check the register value without interrupt. Good idea. Let me give it a try. -- Isaku Yamahata <isaku.yamahata@xxxxxxxxxxxxxxx>
