KVM: nVMX: Shadow VMCS controls on a per-VMCS basis

... to pave the way for not preserving the shadow copies across switches
between vmcs01 and vmcs02, and eventually to avoid VMWRITEs to vmcs02
when the desired value is unchanged across nested VM-Enters.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/vmx/vmcs.h

@@ -42,6 +42,14 @@ struct vmcs_host_state {
 #endif
 };
 
+struct vmcs_controls_shadow {
+	u32 vm_entry;
+	u32 vm_exit;
+	u32 pin;
+	u32 exec;
+	u32 secondary_exec;
+};
+
 /*
  * Track a VMCS that may be loaded on a certain CPU. If it is (cpu!=-1), also
  * remember whether it was VMLAUNCHed, and maintain a linked list of all VMCSs
@@ -61,6 +69,7 @@ struct loaded_vmcs {
 	unsigned long *msr_bitmap;
 	struct list_head loaded_vmcss_on_cpu_link;
 	struct vmcs_host_state host_state;
+	struct vmcs_controls_shadow controls_shadow;
 };
 
 static inline bool is_exception_n(u32 intr_info, u8 vector)

arch/x86/kvm/vmx/vmx.h

@@ -85,14 +85,6 @@ struct pt_desc {
 	struct pt_ctx guest;
 };
 
-struct vmx_controls_shadow {
-	u32 vm_entry;
-	u32 vm_exit;
-	u32 pin;
-	u32 exec;
-	u32 secondary_exec;
-};
-
 /*
  * The nested_vmx structure is part of vcpu_vmx, and holds information we need
  * for correct emulation of VMX (i.e., nested VMX) on this vcpu.
@@ -209,8 +201,6 @@ struct vcpu_vmx {
 	u32                   idt_vectoring_info;
 	ulong                 rflags;
 
-	struct vmx_controls_shadow	controls_shadow;
-
 	struct shared_msr_entry *guest_msrs;
 	int                   nmsrs;
 	int                   save_nmsrs;
@@ -400,21 +390,23 @@ static inline u8 vmx_get_rvi(void)
 #define BUILD_CONTROLS_SHADOW(lname, uname)				    \
 static inline void lname##_controls_reset_shadow(struct vcpu_vmx *vmx)	    \
 {									    \
-	vmx->controls_shadow.lname = vmcs_read32(uname);		    \
+	vmx->loaded_vmcs->controls_shadow.lname = vmcs_read32(uname);	    \
 }									    \
 static inline void lname##_controls_init(struct vcpu_vmx *vmx, u32 val)	    \
 {									    \
 	vmcs_write32(uname, val);					    \
-	vmx->controls_shadow.lname = val;				    \
+	vmx->loaded_vmcs->controls_shadow.lname = val;			    \
 }									    \
 static inline void lname##_controls_set(struct vcpu_vmx *vmx, u32 val)	    \
 {									    \
-	if (vmx->controls_shadow.lname != val)				    \
-		lname##_controls_init(vmx, val);			    \
+	if (vmx->loaded_vmcs->controls_shadow.lname != val) {		    \
+		vmcs_write32(uname, val);				    \
+		vmx->loaded_vmcs->controls_shadow.lname = val;		    \
+	}								    \
 }									    \
 static inline u32 lname##_controls_get(struct vcpu_vmx *vmx)		    \
 {									    \
-	return vmx->controls_shadow.lname;				    \
+	return vmx->loaded_vmcs->controls_shadow.lname;			    \
 }									    \
 static inline void lname##_controls_setbit(struct vcpu_vmx *vmx, u32 val)   \
 {									    \