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Subject: Re: [RESEND v13 01/10] KVM: x86: Move common set/get handler of
 MSR_IA32_DEBUGCTLMSR to VMX
To:     Like Xu <like.xu@linux.intel.com>,
        Sean Christopherson <seanjc@google.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>
Cc:     Ingo Molnar <mingo@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Borislav Petkov <bp@alien8.de>,
        "H . Peter Anvin" <hpa@zytor.com>, ak@linux.intel.com,
        wei.w.wang@intel.com, kan.liang@intel.com, x86@kernel.org,
        kvm@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20210108013704.134985-1-like.xu@linux.intel.com>
 <20210108013704.134985-2-like.xu@linux.intel.com>
From:   Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <a77477a2-cc64-ec8d-1258-f3222b6a358a@redhat.com>
Date:   Tue, 26 Jan 2021 10:25:18 +0100
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On 08/01/21 02:36, Like Xu wrote:
> SVM already has specific handlers of MSR_IA32_DEBUGCTLMSR in the
> svm_get/set_msr, so the x86 common part can be safely moved to VMX.
> 
> Add vmx_supported_debugctl() to refactor the throwing logic of #GP.
> 
> Signed-off-by: Like Xu <like.xu@linux.intel.com>
> Reviewed-by: Andi Kleen <ak@linux.intel.com>
> ---
>   arch/x86/kvm/vmx/capabilities.h |  5 +++++
>   arch/x86/kvm/vmx/vmx.c          | 19 ++++++++++++++++---
>   arch/x86/kvm/x86.c              | 13 -------------
>   3 files changed, 21 insertions(+), 16 deletions(-)
> 
> diff --git a/arch/x86/kvm/vmx/capabilities.h b/arch/x86/kvm/vmx/capabilities.h
> index 3a1861403d73..a58cf3655351 100644
> --- a/arch/x86/kvm/vmx/capabilities.h
> +++ b/arch/x86/kvm/vmx/capabilities.h
> @@ -378,4 +378,9 @@ static inline u64 vmx_get_perf_capabilities(void)
>   	return PMU_CAP_FW_WRITES;
>   }
>   
> +static inline u64 vmx_supported_debugctl(void)
> +{
> +	return DEBUGCTLMSR_LBR | DEBUGCTLMSR_BTF;
> +}
> +
>   #endif /* __KVM_X86_VMX_CAPS_H */
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 2af05d3b0590..23b46327527e 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -1924,6 +1924,9 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
>   		    !guest_cpuid_has(vcpu, X86_FEATURE_RDTSCP))
>   			return 1;
>   		goto find_uret_msr;
> +	case MSR_IA32_DEBUGCTLMSR:
> +		msr_info->data = 0;
> +		break;
>   	default:
>   	find_uret_msr:
>   		msr = vmx_find_uret_msr(vmx, msr_info->index);
> @@ -2002,9 +2005,19 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
>   						VM_EXIT_SAVE_DEBUG_CONTROLS)
>   			get_vmcs12(vcpu)->guest_ia32_debugctl = data;
>   
> -		ret = kvm_set_msr_common(vcpu, msr_info);
> -		break;
> -
> +		if (!data) {
> +			/* We support the non-activated case already */
> +			return 0;
> +		} else if (data & ~vmx_supported_debugctl()) {
> +			/*
> +			 * Values other than LBR and BTF are vendor-specific,
> +			 * thus reserved and should throw a #GP.
> +			 */
> +			return 1;
> +		}
> +		vcpu_unimpl(vcpu, "%s: MSR_IA32_DEBUGCTLMSR 0x%llx, nop\n",
> +			    __func__, data);
> +		return 0;
>   	case MSR_IA32_BNDCFGS:
>   		if (!kvm_mpx_supported() ||
>   		    (!msr_info->host_initiated &&
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 0287840b93e0..c765fd72a66c 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -3063,18 +3063,6 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
>   			return 1;
>   		}
>   		break;
> -	case MSR_IA32_DEBUGCTLMSR:
> -		if (!data) {
> -			/* We support the non-activated case already */
> -			break;
> -		} else if (data & ~(DEBUGCTLMSR_LBR | DEBUGCTLMSR_BTF)) {
> -			/* Values other than LBR and BTF are vendor-specific,
> -			   thus reserved and should throw a #GP */
> -			return 1;
> -		} else if (report_ignored_msrs)
> -			vcpu_unimpl(vcpu, "%s: MSR_IA32_DEBUGCTLMSR 0x%llx, nop\n",
> -				    __func__, data);
> -		break;
>   	case 0x200 ... 0x2ff:
>   		return kvm_mtrr_set_msr(vcpu, msr, data);
>   	case MSR_IA32_APICBASE:
> @@ -3347,7 +3335,6 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
>   	switch (msr_info->index) {
>   	case MSR_IA32_PLATFORM_ID:
>   	case MSR_IA32_EBL_CR_POWERON:
> -	case MSR_IA32_DEBUGCTLMSR:
>   	case MSR_IA32_LASTBRANCHFROMIP:
>   	case MSR_IA32_LASTBRANCHTOIP:
>   	case MSR_IA32_LASTINTFROMIP:
> 

Queued, thanks.

Paolo