linux-kernel - Re: [PATCH v3 12/25] KVM: VMX: Check VM_ENTRY_IA32E_MODE in setup_vmcs

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Date:   Tue, 12 Jul 2022 14:55:03 +0300
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>, kvm@...r.kernel.org,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>
Cc:     Anirudh Rayabharam <anrayabh@...ux.microsoft.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 12/25] KVM: VMX: Check VM_ENTRY_IA32E_MODE in
 setup_vmcs_config()

On Fri, 2022-07-08 at 16:42 +0200, Vitaly Kuznetsov wrote:
> VM_ENTRY_IA32E_MODE control is toggled dynamically by vmx_set_efer()
> and setup_vmcs_config() doesn't check its existence. On the contrary,
> nested_vmx_setup_ctls_msrs() doesn set it on x86_64. Add the missing
> check and filter the bit out in vmx_vmentry_ctrl().
> 
> No (real) functional change intended as all existing CPUs supporting
> long mode and VMX are supposed to have it.
> 
> Reviewed-by: Jim Mattson <jmattson@...gle.com>
> Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
> ---
>  arch/x86/kvm/vmx/vmx.c | 14 +++++++++++---
>  1 file changed, 11 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index dd905ad72637..1aaec4d19e1b 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -2610,6 +2610,9 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf,
>                 _pin_based_exec_control &= ~PIN_BASED_POSTED_INTR;
>  
>         min = VM_ENTRY_LOAD_DEBUG_CONTROLS;
> +#ifdef CONFIG_X86_64
> +       min |= VM_ENTRY_IA32E_MODE;
> +#endif
>         opt = VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL |
>               VM_ENTRY_LOAD_IA32_PAT |
>               VM_ENTRY_LOAD_IA32_EFER |
> @@ -4242,9 +4245,14 @@ static u32 vmx_vmentry_ctrl(void)
>         if (vmx_pt_mode_is_system())
>                 vmentry_ctrl &= ~(VM_ENTRY_PT_CONCEAL_PIP |
>                                   VM_ENTRY_LOAD_IA32_RTIT_CTL);
> -       /* Loading of EFER and PERF_GLOBAL_CTRL are toggled dynamically */
> -       return vmentry_ctrl &
> -               ~(VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL | VM_ENTRY_LOAD_IA32_EFER);
> +       /*
> +        * IA32e mode, and loading of EFER and PERF_GLOBAL_CTRL are toggled dynamically.
> +        */
> +       vmentry_ctrl &= ~(VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL |
> +                         VM_ENTRY_LOAD_IA32_EFER |
> +                         VM_ENTRY_IA32E_MODE);
> +
> +       return vmentry_ctrl;
>  }
>  
>  static u32 vmx_vmexit_ctrl(void)

Reviewed-by: Maxim Levitsky <mlevitsk@...hat.com>

Best regards,
	Maxim Levitsky