linux-kernel - Re: [PATCH 1/2] KVM: vmx, pmu: accept 0 for absent MSRs when host-initiated

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Message-ID: <2b3be388-400e-7871-7d73-aba50d49a9b7@intel.com>
Date:   Wed, 1 Jun 2022 17:12:42 +0800
From:   "Yang, Weijiang" <weijiang.yang@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        likexu@...cent.com
Subject: Re: [PATCH 1/2] KVM: vmx, pmu: accept 0 for absent MSRs when
 host-initiated


On 6/1/2022 4:54 PM, Paolo Bonzini wrote:
> On 5/31/22 20:37, Sean Christopherson wrote:
>>> +
>>>           /*
>>>            * Writing depth MSR from guest could either setting the
>>>            * MSR or resetting the LBR records with the side-effect.
>>> @@ -535,6 +542,8 @@ static int intel_pmu_set_msr(struct kvm_vcpu 
>>> *vcpu, struct msr_data *msr_info)
>>>       case MSR_ARCH_LBR_CTL:
>>>           if (!arch_lbr_ctl_is_valid(vcpu, data))
>>>               break;
>>> +        if (!guest_cpuid_has(vcpu, X86_FEATURE_ARCH_LBR))
>>> +            return 0;
>>
>> Similar bug here.
>>
>> Can we just punt this out of kvm/queue until its been properly reviewed?
>
> Yes, I agree.  I have started making some changes and pushed the 
> result to kvm/arch-lbr-for-weijiang.
>
> Most of the MSR handling is rewritten (and untested).
>
> The nested VMX handling was also completely broken so I just removed 
> it.  Instead, KVM should be adjusted so that it does not whine.

Noted, I'll run tests based on it, thanks a lot!

Has the branch been pushed? I cannot see it.

>
> Paolo
>