linux-kernel - Re: [PATCH v3 17/25] KVM: VMX: Add missing VMEXIT controls to vmcs

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Date:   Tue, 12 Jul 2022 14:57:11 +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 17/25] KVM: VMX: Add missing VMEXIT controls to
 vmcs_config

On Fri, 2022-07-08 at 16:42 +0200, Vitaly Kuznetsov wrote:
> As a preparation to reusing the result of setup_vmcs_config() in
> nested VMX MSR setup, add the VMEXIT controls which KVM doesn't
> use but supports for nVMX to KVM_OPT_VMX_VM_EXIT_CONTROLS and
> filter them out in vmx_vmexit_ctrl().
> 
> No functional change intended.
> 
> Reviewed-by: Jim Mattson <jmattson@...gle.com>
> Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
> ---
>  arch/x86/kvm/vmx/vmx.c | 4 ++++
>  arch/x86/kvm/vmx/vmx.h | 3 +++
>  2 files changed, 7 insertions(+)
> 
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index d7170990f469..2fb89bdcbbd8 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -4196,6 +4196,10 @@ static u32 vmx_vmexit_ctrl(void)
>  {
>         u32 vmexit_ctrl = vmcs_config.vmexit_ctrl;
>  
> +       /* Not used by KVM but supported for nesting. */
> +       vmexit_ctrl &= ~(VM_EXIT_SAVE_IA32_PAT | VM_EXIT_SAVE_IA32_EFER |
> +                        VM_EXIT_SAVE_VMX_PREEMPTION_TIMER);
> +
>         if (vmx_pt_mode_is_system())
>                 vmexit_ctrl &= ~(VM_EXIT_PT_CONCEAL_PIP |
>                                  VM_EXIT_CLEAR_IA32_RTIT_CTL);
> diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
> index 89eaab3495a6..e9c392398f1b 100644
> --- a/arch/x86/kvm/vmx/vmx.h
> +++ b/arch/x86/kvm/vmx/vmx.h
> @@ -498,8 +498,11 @@ static inline u8 vmx_get_rvi(void)
>  #endif
>  #define KVM_OPT_VMX_VM_EXIT_CONTROLS                           \
>               (VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL |             \
> +             VM_EXIT_SAVE_IA32_PAT |                           \
>               VM_EXIT_LOAD_IA32_PAT |                           \
> +             VM_EXIT_SAVE_IA32_EFER |                          \
>               VM_EXIT_LOAD_IA32_EFER |                          \
> +             VM_EXIT_SAVE_VMX_PREEMPTION_TIMER |               \
>               VM_EXIT_CLEAR_BNDCFGS |                           \
>               VM_EXIT_PT_CONCEAL_PIP |                          \
>               VM_EXIT_CLEAR_IA32_RTIT_CTL)


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

Best regards,
	Maxim Levitsky