linux-kernel - Re: [PATCH v2] kvm: nVMX: Set nested_run_pending in vmx_set_nested

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Message-ID: <20190508142023.GA13834@linux.intel.com>
Date:   Wed, 8 May 2019 07:20:23 -0700
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        Peter Shier <pshier@...gle.com>,
        Aaron Lewis <aaronlewis@...gle.com>
Subject: Re: [PATCH v2] kvm: nVMX: Set nested_run_pending in
 vmx_set_nested_state after checks complete

On Wed, May 08, 2019 at 02:16:39PM +0200, Paolo Bonzini wrote:
> From: Aaron Lewis <aaronlewis@...gle.com>

If this is actually attributed to Aaron it needs his SOB.

> nested_run_pending=1 implies we have successfully entered guest mode.
> Move setting from external state in vmx_set_nested_state() until after
> all other checks are complete.

It'd be helpful to at least mention the flag is consumed by
nested_vmx_enter_non_root_mode().

> Based on a patch by Aaron Lewis.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
> ---

For the code itself:

Reviewed-by: Sean Christopherson <sean.j.christopherson@...el.com> 

>  arch/x86/kvm/vmx/nested.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> index cec77f30f61c..e58caff92694 100644
> --- a/arch/x86/kvm/vmx/nested.c
> +++ b/arch/x86/kvm/vmx/nested.c
> @@ -5420,9 +5420,6 @@ static int vmx_set_nested_state(struct kvm_vcpu *vcpu,
>  	if (!(kvm_state->flags & KVM_STATE_NESTED_GUEST_MODE))
>  		return 0;
>  
> -	vmx->nested.nested_run_pending =
> -		!!(kvm_state->flags & KVM_STATE_NESTED_RUN_PENDING);
> -
>  	if (nested_cpu_has_shadow_vmcs(vmcs12) &&
>  	    vmcs12->vmcs_link_pointer != -1ull) {
>  		struct vmcs12 *shadow_vmcs12 = get_shadow_vmcs12(vcpu);
> @@ -5446,9 +5443,14 @@ static int vmx_set_nested_state(struct kvm_vcpu *vcpu,
>  		return -EINVAL;
>  
>  	vmx->nested.dirty_vmcs12 = true;
> +	vmx->nested.nested_run_pending =
> +		!!(kvm_state->flags & KVM_STATE_NESTED_RUN_PENDING);
> +
>  	ret = nested_vmx_enter_non_root_mode(vcpu, false);
> -	if (ret)
> +	if (ret) {
> +		vmx->nested.nested_run_pending = 0;
>  		return -EINVAL;
> +	}
>  
>  	return 0;
>  }
> -- 
> 1.8.3.1
>