KVM: vmx: add mismatched size assertions in vmcs_check32()

Add compile-time assertions in vmcs_check32() to disallow accesses to
64-bit and 64-bit high fields via vmcs_{read,write}32().  Upper level KVM
code should never do partial accesses to VMCS fields.  KVM handles the
split accesses automatically in vmcs_{read,write}64() when running as a
32-bit kernel.
Reviewed-and-tested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Haiwei Li <lihaiwei@tencent.com>
Message-Id: <20210409022456.23528-1-lihaiwei.kernel@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/vmx/vmx_ops.h

@@ -37,6 +37,10 @@ static __always_inline void vmcs_check32(unsigned long field)
 {
 	BUILD_BUG_ON_MSG(__builtin_constant_p(field) && ((field) & 0x6000) == 0,
 			 "32-bit accessor invalid for 16-bit field");
+	BUILD_BUG_ON_MSG(__builtin_constant_p(field) && ((field) & 0x6001) == 0x2000,
+			 "32-bit accessor invalid for 64-bit field");
+	BUILD_BUG_ON_MSG(__builtin_constant_p(field) && ((field) & 0x6001) == 0x2001,
+			 "32-bit accessor invalid for 64-bit high field");
 	BUILD_BUG_ON_MSG(__builtin_constant_p(field) && ((field) & 0x6000) == 0x6000,
 			 "32-bit accessor invalid for natural width field");
 }