Re: [PATCH v2 20/28] KVM: VMX: Add missing VMENTRY controls to vmcs_config

[Vitaly Kuznetsov <vkuznets@redhat.com>]

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