linux-kernel - Re: [PATCH 2/3] KVM: eVMCS: check if nesting is enabled

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Message-ID: <877dyatubz.fsf@vitty.brq.redhat.com>
Date:   Mon, 20 Apr 2020 10:49:52 +0200
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     Paolo Bonzini <pbonzini@...hat.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     Sean Christopherson <sean.j.christopherson@...el.com>
Subject: Re: [PATCH 2/3] KVM: eVMCS: check if nesting is enabled

Paolo Bonzini <pbonzini@...hat.com> writes:

> In the next patch nested_get_evmcs_version will be always set in kvm_x86_ops for
> VMX, even if nesting is disabled.  Therefore, check whether VMX (aka nesting)
> is available in the function, the caller will not do the check anymore.
>
> Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
> ---
>  arch/x86/kvm/vmx/evmcs.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/vmx/evmcs.c b/arch/x86/kvm/vmx/evmcs.c
> index 73f3e07c1852..48dc77de9337 100644
> --- a/arch/x86/kvm/vmx/evmcs.c
> +++ b/arch/x86/kvm/vmx/evmcs.c
> @@ -4,6 +4,7 @@
>  #include <linux/smp.h>
>  
>  #include "../hyperv.h"
> +#include "../cpuid.h"
>  #include "evmcs.h"
>  #include "vmcs.h"
>  #include "vmx.h"
> @@ -333,7 +334,8 @@ uint16_t nested_get_evmcs_version(struct kvm_vcpu *vcpu)
>          * maximum supported version. KVM supports versions from 1 to
>          * KVM_EVMCS_VERSION.
>          */
> -       if (vmx->nested.enlightened_vmcs_enabled)
> +       if (kvm_cpu_cap_get(X86_FEATURE_VMX) &&
> +	   vmx->nested.enlightened_vmcs_enabled)
>                 return (KVM_EVMCS_VERSION << 8) | 1;
>  
>         return 0;

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

-- 
Vitaly