Messages in this thread | | | From | Vitaly Kuznetsov <> | Subject | Re: [PATCH v4 6/6] KVM: selftests: Test Hyper-V invariant TSC control | Date | Thu, 13 Oct 2022 11:16:22 +0200 |
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Sean Christopherson <seanjc@google.com> writes:
> On Wed, Oct 12, 2022, Vitaly Kuznetsov wrote: >> Sean Christopherson <seanjc@google.com> writes: >>
...
>> > Aha! Idea. Assuming none of the MSRs are write-only, what about adding a prep >> > patch to rework this code so that it verifies RDMSR returns what was written when >> > a fault didn't occur. >> > >> >> There is at least one read-only MSR which comes to mind: >> HV_X64_MSR_EOI. > > I assume s/read-only/write-only since it's EOI? >
Yes, of course)
>> Also, some of the MSRs don't preserve the written value, >> e.g. HV_X64_MSR_RESET which always reads as '0'. > > Hrm, that's annoying.
'Slightly annoying'. In fact, the test never writes anything besides '0' to the MSR as the code is not ready to handle real vCPU reset. I'll leave a TODO note about that.
...
> static bool is_write_only_msr(uint32_t msr) > { > return msr == HV_X64_MSR_EOI; > }
This is all we need, basically. I'll go with that.
-- Vitaly
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