Re: [PATCH RESEND v12 00/17] KVM: x86/pmu: Add basic support to enable guest PEBS via DS

[Like Xu]

On 19/5/2022 8:14 pm, Vitaly Kuznetsov wrote:
> Like Xu <like.xu.linux@xxxxxxxxx> writes:
>
> ...
>
> Hi, the following commit
>
> >    KVM: x86/pmu: Add IA32_PEBS_ENABLE MSR emulation for extended PEBS
>
> (currently in kvm/queue) breaks a number of selftests, e.g.:

Indeed, e.g.:

x86_64/hyperv_clock
x86_64/max_vcpuid_cap_test
x86_64/mmu_role_test

> # ./tools/testing/selftests/kvm/x86_64/state_test

This test continues to be silent after the top commit a3808d884612 ("KVM: x86/pmu:
Expose CPUIDs feature bits PDCM, DS, DTES64"), which implies a root cause.

Anyway, thanks for this git-bisect report.

> ==== Test Assertion Failure ====
>    lib/x86_64/processor.c:1207: r == nmsrs
>    pid=6702 tid=6702 errno=7 - Argument list too long
>       1	0x000000000040da11: vcpu_save_state at processor.c:1207 (discriminator 4)
>       2	0x00000000004024e5: main at state_test.c:209 (discriminator 6)
>       3	0x00007f9f48c2d55f: ?? ??:0
>       4	0x00007f9f48c2d60b: ?? ??:0
>       5	0x00000000004026d4: _start at ??:?
>    Unexpected result from KVM_GET_MSRS, r: 29 (failed MSR was 0x3f1)
>
> I don't think any of these failing tests care about MSR_IA32_PEBS_ENABLE
> in particular, they're just trying to do KVM_GET_MSRS/KVM_SET_MSRS.