linux-kernel - Re: [PATCH] KVM: nVMX: fix comments of handle

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Message-ID: <20210908130145.3uwmywgjaahyb6iw@linux.intel.com>
Date:   Wed, 8 Sep 2021 21:01:45 +0800
From:   Yu Zhang <yu.c.zhang@...ux.intel.com>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>
Cc:     seanjc@...gle.com, pbonzini@...hat.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, wanpengli@...cent.com,
        jmattson@...gle.com, joro@...tes.org
Subject: Re: [PATCH] KVM: nVMX: fix comments of handle_vmon()

On Wed, Sep 08, 2021 at 11:55:59AM +0200, Vitaly Kuznetsov wrote:
> Indeed,
> 
> Reviewed-by: Vitaly Kuznetsov <vkuznets@...hat.com>
> 
> On a slightly related note: we don't seem to reset
> 'vmx->nested.vmxon_ptr' upon VMXOFF emulation; this is not a problem per
> se as we never access it when !vmx->nested.vmxon but I'd still suggest
> we do something like
> 
> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> index bc6327950657..8beb41d02d21 100644
> --- a/arch/x86/kvm/vmx/nested.c
> +++ b/arch/x86/kvm/vmx/nested.c
> @@ -290,6 +290,7 @@ static void free_nested(struct kvm_vcpu *vcpu)
>  
>         vmx->nested.vmxon = false;
>         vmx->nested.smm.vmxon = false;
> +       vmx->nested.vmxon_ptr = -1ull;
>         free_vpid(vmx->nested.vpid02);
>         vmx->nested.posted_intr_nv = -1;
>         vmx->nested.current_vmptr = -1ull;
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index d7c5257eb5c0..2214e6bd4713 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -6884,6 +6884,7 @@ static int vmx_create_vcpu(struct kvm_vcpu *vcpu)
>  
>         vcpu_setup_sgx_lepubkeyhash(vcpu);
>  
> +       vmx->nested.vmxon_ptr = -1ull;
>         vmx->nested.posted_intr_nv = -1;
>         vmx->nested.current_vmptr = -1ull;
>         vmx->nested.hv_evmcs_vmptr = EVMPTR_INVALID;
> 
> to avoid issues in the future.
> 
Thanks, Vitaly. And above suggestion sounds reasonable to me. :)

I can add this in V2 later, if no one objects. 

B.R.
Yu