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From:   Vitaly Kuznetsov <vkuznets@redhat.com>
To:     Jim Mattson <jmattson@google.com>
Cc:     kvm@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>,
        Sean Christopherson <seanjc@google.com>,
        Anirudh Rayabharam <anrayabh@linux.microsoft.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Maxim Levitsky <mlevitsk@redhat.com>,
        linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 20/28] KVM: VMX: Add missing VMENTRY controls to
 vmcs_config
In-Reply-To: <CALMp9eTVAOCvWQ-3A6VmwhJk6skES9phMPC3O-za7Rk05SfVTg@mail.gmail.com>
References: <20220629150625.238286-1-vkuznets@redhat.com>
 <20220629150625.238286-21-vkuznets@redhat.com>
 <CALMp9eTVAOCvWQ-3A6VmwhJk6skES9phMPC3O-za7Rk05SfVTg@mail.gmail.com>
Date:   Thu, 07 Jul 2022 12:41:26 +0200
Message-ID: <87fsjdqk6h.fsf@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain
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Jim Mattson <jmattson@google.com> writes:

> On Wed, Jun 29, 2022 at 8:07 AM Vitaly Kuznetsov <vkuznets@redhat.com> wrote:
>>
>> As a preparation to reusing the result of setup_vmcs_config() in
>> nested VMX MSR setup, add the VMENTRY controls which KVM doesn't
>> use but supports for nVMX to KVM_OPT_VMX_VM_ENTRY_CONTROLS and
>> filter them out in vmx_vmentry_ctrl().
>>
>> No functional change intended.
>>
>> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
>> ---
>>  arch/x86/kvm/vmx/vmx.c | 3 +++
>>  arch/x86/kvm/vmx/vmx.h | 4 +++-
>>  2 files changed, 6 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
>> index e5ab77ed37e4..b774b6391e0e 100644
>> --- a/arch/x86/kvm/vmx/vmx.c
>> +++ b/arch/x86/kvm/vmx/vmx.c
>> @@ -4179,6 +4179,9 @@ static u32 vmx_vmentry_ctrl(void)
>>  {
>>         u32 vmentry_ctrl = vmcs_config.vmentry_ctrl;
>>
>> +       /* Not used by KVM but supported for nesting. */
>> +       vmentry_ctrl &= ~(VM_ENTRY_SMM | VM_ENTRY_DEACT_DUAL_MONITOR);
>> +
>
> LOL! KVM does not emulate the dual-monitor treatment of SMIs and SMM.
> Do we actually claim to support these VM-entry controls today?!?
>

No, just a brainfart on my side, nested_vmx_setup_ctls_msrs() filters
them out too. I'll drop the patch.

>>         if (vmx_pt_mode_is_system())
>>                 vmentry_ctrl &= ~(VM_ENTRY_PT_CONCEAL_PIP |
>>                                   VM_ENTRY_LOAD_IA32_RTIT_CTL);
>> diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
>> index d4503a38735b..7ada8410a037 100644
>> --- a/arch/x86/kvm/vmx/vmx.h
>> +++ b/arch/x86/kvm/vmx/vmx.h
>> @@ -479,7 +479,9 @@ static inline u8 vmx_get_rvi(void)
>>                 __KVM_REQ_VMX_VM_ENTRY_CONTROLS
>>  #endif
>>  #define KVM_OPT_VMX_VM_ENTRY_CONTROLS                          \
>> -       (VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL |                  \
>> +       (VM_ENTRY_SMM |                                         \
>> +       VM_ENTRY_DEACT_DUAL_MONITOR |                           \
>> +       VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL |                   \
>>         VM_ENTRY_LOAD_IA32_PAT |                                \
>>         VM_ENTRY_LOAD_IA32_EFER |                               \
>>         VM_ENTRY_LOAD_BNDCFGS |                                 \
>> --
>> 2.35.3
>>
>

-- 
Vitaly