On Fri, 2024-06-14 at 07:26 -0700, Sean Christopherson wrote: > On Thu, Jun 13, 2024, Maxim Levitsky wrote: > > Hi! > > > > This kvm unit test tests that all reserved bits of the MSR_IA32_FLUSH_CMD #GP, but apparently > > on some systems this test fails. > > > > For example I reproduced this on: > > > > model name : Intel(R) Xeon(R) CPU E3-1260L v5 @ 2.90GHz > > stepping : 3 > > microcode : 0xf0 > > > > > > As I see in the 'vmx_vcpu_after_set_cpuid', we passthough this msr to the guest AS IS, > > thus the unit test tests the microcode. > > > > So I suspect that the test actually caught a harmless microcode bug. > > Yeah, we encountered the same thing and came to the same conclusion. > > > What do you think we should do to workaround this? Maybe disable this check on > > affected cpus or turn it into a warning because MSR_IA32_FLUSH_CMD reserved bits > > test doesn't test KVM? > > Ya, Mingwei posted a patch[*] to force KVM to emulate the faulting accesses, which > more or less does exactly that, but preserves a bit of KVM coverage. I'll get a > KUT pull request sent to Paolo today, I've got a sizeable number of changes ready. > > [*] https://lore.kernel.org/all/20240417232906.3057638-3-mizhang@xxxxxxxxxx > This works for me. Thanks, Best regards, Maxim Levitsky
