linux-kernel - Re: [PATCH RFC 1/3] x86/kvm/hyper-v: remove stale evmcs_already_enabled check from nested_enable

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Message-Id: <7CBE44B7-E554-480D-9280-E29247C70178@oracle.com>
Date:   Thu, 16 Jan 2020 00:50:39 +0200
From:   Liran Alon <liran.alon@...cle.com>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>
Cc:     kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Jim Mattson <jmattson@...gle.com>,
        linux-kernel@...r.kernel.org, Roman Kagan <rkagan@...tuozzo.com>
Subject: Re: [PATCH RFC 1/3] x86/kvm/hyper-v: remove stale
 evmcs_already_enabled check from nested_enable_evmcs()



> On 15 Jan 2020, at 19:10, Vitaly Kuznetsov <vkuznets@...hat.com> wrote:
> 
> In nested_enable_evmcs() evmcs_already_enabled check doesn't really do
> anything: controls are already sanitized and we return '0' regardless.
> Just drop the check.
> 
> Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>

Reviewed-by: Liran Alon <liran.alon@...cle.com>

-Liran

> ---
> arch/x86/kvm/vmx/evmcs.c | 5 -----
> 1 file changed, 5 deletions(-)
> 
> diff --git a/arch/x86/kvm/vmx/evmcs.c b/arch/x86/kvm/vmx/evmcs.c
> index 72359709cdc1..89c3e0caf39f 100644
> --- a/arch/x86/kvm/vmx/evmcs.c
> +++ b/arch/x86/kvm/vmx/evmcs.c
> @@ -350,17 +350,12 @@ int nested_enable_evmcs(struct kvm_vcpu *vcpu,
> 			uint16_t *vmcs_version)
> {
> 	struct vcpu_vmx *vmx = to_vmx(vcpu);
> -	bool evmcs_already_enabled = vmx->nested.enlightened_vmcs_enabled;
> 
> 	vmx->nested.enlightened_vmcs_enabled = true;
> 
> 	if (vmcs_version)
> 		*vmcs_version = nested_get_evmcs_version(vcpu);
> 
> -	/* We don't support disabling the feature for simplicity. */
> -	if (evmcs_already_enabled)
> -		return 0;
> -
> 	vmx->nested.msrs.pinbased_ctls_high &= ~EVMCS1_UNSUPPORTED_PINCTRL;
> 	vmx->nested.msrs.entry_ctls_high &= ~EVMCS1_UNSUPPORTED_VMENTRY_CTRL;
> 	vmx->nested.msrs.exit_ctls_high &= ~EVMCS1_UNSUPPORTED_VMEXIT_CTRL;
> -- 
> 2.24.1
>