KVM: VMX: Add missing VMEXIT controls to vmcs_config

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@google.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20220830133737.1539624-26-vkuznets@redhat.comSigned-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/vmx/vmx.c

@@ -4279,6 +4279,13 @@ static u32 vmx_vmexit_ctrl(void)
 {
 	u32 vmexit_ctrl = vmcs_config.vmexit_ctrl;
 
+	/*
+	 * Not used by KVM and never set in vmcs01 or vmcs02, but emulated for
+	 * nested virtualization and thus allowed to be set in vmcs12.
+	 */
+	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);

arch/x86/kvm/vmx/vmx.h

@@ -508,7 +508,10 @@ static inline u8 vmx_get_rvi(void)
 #endif
 #define KVM_OPTIONAL_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_SAVE_VMX_PREEMPTION_TIMER |			\
 	       VM_EXIT_LOAD_IA32_EFER |					\
 	       VM_EXIT_CLEAR_BNDCFGS |					\
 	       VM_EXIT_PT_CONCEAL_PIP |					\