linux-kernel - Re: [PATCH 04/26] KVM: x86: Add a kvm_x86_ops hook to query virtualized MSR support

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Date:   Wed, 05 Feb 2020 15:34:29 +0100
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     Sean Christopherson <sean.j.christopherson@...el.com>
Cc:     Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>
Subject: Re: [PATCH 04/26] KVM: x86: Add a kvm_x86_ops hook to query virtualized MSR support

Sean Christopherson <sean.j.christopherson@...el.com> writes:

> Add a hook, ->has_virtualized_msr(), to allow moving vendor specific
> checks into SVM/VMX and ultimately facilitate the removal of the
> piecemeal ->*_supported() hooks.
>
> No functional change intended.
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
> ---
>  arch/x86/include/asm/kvm_host.h | 1 +
>  arch/x86/kvm/svm.c              | 6 ++++++
>  arch/x86/kvm/vmx/vmx.c          | 6 ++++++
>  arch/x86/kvm/x86.c              | 2 ++
>  4 files changed, 15 insertions(+)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 5c2ad3fa0980..8fb32c27fa44 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1050,6 +1050,7 @@ struct kvm_x86_ops {
>  	int (*hardware_setup)(void);               /* __init */
>  	void (*hardware_unsetup)(void);            /* __exit */
>  	bool (*cpu_has_accelerated_tpr)(void);
> +	bool (*has_virtualized_msr)(u32 index);
>  	bool (*has_emulated_msr)(u32 index);
>  	void (*cpuid_update)(struct kvm_vcpu *vcpu);
>  
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index a7b944a3a0e2..1f9323fbad81 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -5985,6 +5985,11 @@ static bool svm_cpu_has_accelerated_tpr(void)
>  	return false;
>  }
>  
> +static bool svm_has_virtualized_msr(u32 index)
> +{
> +	return true;
> +}
> +
>  static bool svm_has_emulated_msr(u32 index)
>  {
>  	switch (index) {
> @@ -7379,6 +7384,7 @@ static struct kvm_x86_ops svm_x86_ops __ro_after_init = {
>  	.hardware_enable = svm_hardware_enable,
>  	.hardware_disable = svm_hardware_disable,
>  	.cpu_has_accelerated_tpr = svm_cpu_has_accelerated_tpr,
> +	.has_virtualized_msr = svm_has_virtualized_msr,
>  	.has_emulated_msr = svm_has_emulated_msr,
>  
>  	.vcpu_create = svm_create_vcpu,
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index f5bb1ad2e9fa..3f2c094434e8 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -6274,6 +6274,11 @@ static void vmx_handle_exit_irqoff(struct kvm_vcpu *vcpu,
>  		*exit_fastpath = handle_fastpath_set_msr_irqoff(vcpu);
>  }
>  
> +static bool vmx_has_virtualized_msr(u32 index)
> +{
> +	return true;
> +}
> +
>  static bool vmx_has_emulated_msr(u32 index)
>  {
>  	switch (index) {
> @@ -7754,6 +7759,7 @@ static struct kvm_x86_ops vmx_x86_ops __ro_after_init = {
>  	.hardware_enable = hardware_enable,
>  	.hardware_disable = hardware_disable,
>  	.cpu_has_accelerated_tpr = report_flexpriority,
> +	.has_virtualized_msr = vmx_has_virtualized_msr,
>  	.has_emulated_msr = vmx_has_emulated_msr,
>  
>  	.vm_init = vmx_vm_init,
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 3d4a5326d84e..94f90fe1c0de 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -5279,6 +5279,8 @@ static void kvm_init_msr_list(void)
>  				continue;
>  			break;
>  		default:
> +			if (!kvm_x86_ops->has_virtualized_msr(msr_index))
> +				continue;
>  			break;
>  		}

Shouldn't break anything by itself, so

Reviewed-by: Vitaly Kuznetsov <vkuznets@...hat.com>

-- 
Vitaly