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

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Message-ID: <87ilzb4216.fsf@vitty.brq.redhat.com>
Date:   Wed, 08 Sep 2021 15:42:13 +0200
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     Yu Zhang <yu.c.zhang@...ux.intel.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()

Yu Zhang <yu.c.zhang@...ux.intel.com> writes:

> 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. 
>

Sure, this is rather a separate patch. Thanks!

-- 
Vitaly