linux-kernel - Re: [PATCH v3 4/8] KVM: X86: Split kvm_update

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Message-ID: <ad349b28-bc62-e478-c610-e829974a8342@redhat.com>
Date:   Wed, 8 Jul 2020 14:06:02 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Xiaoyao Li <xiaoyao.li@...el.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Jim Mattson <jmattson@...gle.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org, Jonathan Corbet <corbet@....net>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Joerg Roedel <joro@...tes.org>
Subject: Re: [PATCH v3 4/8] KVM: X86: Split kvm_update_cpuid()

On 08/07/20 08:50, Xiaoyao Li wrote:
> Split the part of updating vcpu model out of kvm_update_cpuid(), and put
> it into a new kvm_update_vcpu_model(). So it's more clear that
> kvm_update_cpuid() is to update guest CPUID settings, while
> kvm_update_vcpu_model() is to update vcpu model (settings) based on the
> updated CPUID settings.
> 
> Signed-off-by: Xiaoyao Li <xiaoyao.li@...el.com>

I would prefer to keep the kvm_update_cpuid name for what you called
kvm_update_vcpu_model(), and rename the rest to kvm_update_cpuid_runtime().

Paolo

> ---
>  arch/x86/kvm/cpuid.c | 38 ++++++++++++++++++++++++--------------
>  arch/x86/kvm/cpuid.h |  1 +
>  arch/x86/kvm/x86.c   |  1 +
>  3 files changed, 26 insertions(+), 14 deletions(-)
> 
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index a825878b7f84..001f5a94880e 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -76,7 +76,6 @@ static int kvm_check_cpuid(struct kvm_vcpu *vcpu)
>  void kvm_update_cpuid(struct kvm_vcpu *vcpu)
>  {
>  	struct kvm_cpuid_entry2 *best;
> -	struct kvm_lapic *apic = vcpu->arch.apic;
>  
>  	best = kvm_find_cpuid_entry(vcpu, 1, 0);
>  	if (best) {
> @@ -89,26 +88,14 @@ void kvm_update_cpuid(struct kvm_vcpu *vcpu)
>  			   vcpu->arch.apic_base & MSR_IA32_APICBASE_ENABLE);
>  	}
>  
> -	if (best && apic) {
> -		if (cpuid_entry_has(best, X86_FEATURE_TSC_DEADLINE_TIMER))
> -			apic->lapic_timer.timer_mode_mask = 3 << 17;
> -		else
> -			apic->lapic_timer.timer_mode_mask = 1 << 17;
> -	}
> -
>  	best = kvm_find_cpuid_entry(vcpu, 7, 0);
>  	if (best && boot_cpu_has(X86_FEATURE_PKU) && best->function == 0x7)
>  		cpuid_entry_change(best, X86_FEATURE_OSPKE,
>  				   kvm_read_cr4_bits(vcpu, X86_CR4_PKE));
>  
>  	best = kvm_find_cpuid_entry(vcpu, 0xD, 0);
> -	if (!best) {
> -		vcpu->arch.guest_supported_xcr0 = 0;
> -	} else {
> -		vcpu->arch.guest_supported_xcr0 =
> -			(best->eax | ((u64)best->edx << 32)) & supported_xcr0;
> +	if (best)
>  		best->ebx = xstate_required_size(vcpu->arch.xcr0, false);
> -	}
>  
>  	best = kvm_find_cpuid_entry(vcpu, 0xD, 1);
>  	if (best && (cpuid_entry_has(best, X86_FEATURE_XSAVES) ||
> @@ -127,6 +114,27 @@ void kvm_update_cpuid(struct kvm_vcpu *vcpu)
>  					   vcpu->arch.ia32_misc_enable_msr &
>  					   MSR_IA32_MISC_ENABLE_MWAIT);
>  	}
> +}
> +
> +void kvm_update_vcpu_model(struct kvm_vcpu *vcpu)
> +{
> +	struct kvm_lapic *apic = vcpu->arch.apic;
> +	struct kvm_cpuid_entry2 *best;
> +
> +	best = kvm_find_cpuid_entry(vcpu, 1, 0);
> +	if (best && apic) {
> +		if (cpuid_entry_has(best, X86_FEATURE_TSC_DEADLINE_TIMER))
> +			apic->lapic_timer.timer_mode_mask = 3 << 17;
> +		else
> +			apic->lapic_timer.timer_mode_mask = 1 << 17;
> +	}
> +
> +	best = kvm_find_cpuid_entry(vcpu, 0xD, 0);
> +	if (!best)
> +		vcpu->arch.guest_supported_xcr0 = 0;
> +	else
> +		vcpu->arch.guest_supported_xcr0 =
> +			(best->eax | ((u64)best->edx << 32)) & supported_xcr0;
>  
>  	/* Note, maxphyaddr must be updated before tdp_level. */
>  	vcpu->arch.maxphyaddr = cpuid_query_maxphyaddr(vcpu);
> @@ -218,6 +226,7 @@ int kvm_vcpu_ioctl_set_cpuid(struct kvm_vcpu *vcpu,
>  	kvm_apic_set_version(vcpu);
>  	kvm_x86_ops.cpuid_update(vcpu);
>  	kvm_update_cpuid(vcpu);
> +	kvm_update_vcpu_model(vcpu);
>  
>  	kvfree(cpuid_entries);
>  out:
> @@ -247,6 +256,7 @@ int kvm_vcpu_ioctl_set_cpuid2(struct kvm_vcpu *vcpu,
>  	kvm_apic_set_version(vcpu);
>  	kvm_x86_ops.cpuid_update(vcpu);
>  	kvm_update_cpuid(vcpu);
> +	kvm_update_vcpu_model(vcpu);
>  out:
>  	return r;
>  }
> diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
> index f136de1debad..45e3643e2fba 100644
> --- a/arch/x86/kvm/cpuid.h
> +++ b/arch/x86/kvm/cpuid.h
> @@ -10,6 +10,7 @@ extern u32 kvm_cpu_caps[NCAPINTS] __read_mostly;
>  void kvm_set_cpu_caps(void);
>  
>  void kvm_update_cpuid(struct kvm_vcpu *vcpu);
> +void kvm_update_vcpu_model(struct kvm_vcpu *vcpu);
>  struct kvm_cpuid_entry2 *kvm_find_cpuid_entry(struct kvm_vcpu *vcpu,
>  					      u32 function, u32 index);
>  int kvm_dev_ioctl_get_cpuid(struct kvm_cpuid2 *cpuid,
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 09ee54f5e385..6f376392e6e6 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -8184,6 +8184,7 @@ static void enter_smm(struct kvm_vcpu *vcpu)
>  #endif
>  
>  	kvm_update_cpuid(vcpu);
> +	kvm_update_vcpu_model(vcpu);
>  	kvm_mmu_reset_context(vcpu);
>  }
>  
>