From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Nadav Amit <nadav.amit@gmail.com>
Cc: Aaron Lewis <aaronlewis@google.com>,
kvm list <kvm@vger.kernel.org>, Jim Mattson <jmattson@google.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Liran Alon <liran.alon@oracle.com>
Subject: Re: [kvm-unit-tests PATCH v3] x86: Add RDTSC test
Date: Fri, 24 Jan 2020 15:38:35 -0800 [thread overview]
Message-ID: <20200124233835.GT2109@linux.intel.com> (raw)
In-Reply-To: <4EFDEFF2-D1CD-4AF3-9EF8-5F160A4D93CD@gmail.com>
On Fri, Jan 24, 2020 at 03:13:44PM -0800, Nadav Amit wrote:
> > On Dec 2, 2019, at 12:43 PM, Aaron Lewis <aaronlewis@google.com> wrote:
> >
> > Verify that the difference between a guest RDTSC instruction and the
> > IA32_TIME_STAMP_COUNTER MSR value stored in the VMCS12's VM-exit
> > MSR-store list is less than 750 cycles, 99.9% of the time.
> >
> > 662f1d1d1931 ("KVM: nVMX: Add support for capturing highest observable L2 TSC”)
> >
> > Signed-off-by: Aaron Lewis <aaronlewis@google.com>
> > Reviewed-by: Jim Mattson <jmattson@google.com>
>
> Running this test on bare-metal I get:
>
> Test suite: rdtsc_vmexit_diff_test
> FAIL: RDTSC to VM-exit delta too high in 117 of 100000 iterations
>
> Any idea why? Should I just play with the 750 cycles magic number?
Argh, this reminds me that I have a patch for this test to improve the
error message to makes things easier to debug. Give me a few minutes to
get it sent out, might help a bit.
next prev parent reply other threads:[~2020-01-24 23:40 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-02 20:43 [kvm-unit-tests PATCH v3] x86: Add RDTSC test Aaron Lewis
2019-12-03 1:51 ` Liran Alon
2019-12-04 11:48 ` Paolo Bonzini
2020-01-24 23:13 ` Nadav Amit
2020-01-24 23:38 ` Sean Christopherson [this message]
2020-01-25 0:06 ` Nadav Amit
2020-01-26 22:06 ` Jim Mattson
2020-01-27 4:36 ` Nadav Amit
2020-01-27 19:24 ` Jim Mattson
2020-01-27 20:56 ` Sean Christopherson
2020-01-28 17:59 ` Jim Mattson
2020-01-28 18:32 ` Nadav Amit
2020-01-28 18:33 ` Sean Christopherson
2020-01-28 18:42 ` Nadav Amit
2020-01-28 18:43 ` Jim Mattson
2020-01-28 19:03 ` Nadav Amit
2020-01-28 19:34 ` Jim Mattson
2020-01-25 9:43 ` Paolo Bonzini
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