[PATCH net] hamradio: baycom_epp: fix build for UML

[Randy Dunlap]

On i386, the baycom_epp driver wants to inspect X86 CPU features (TSC)
and then act on that data, but that info is not available when running
on UML, so prevent that test and do the default action.

Prevents this build error on UML + i386:

../drivers/net/hamradio/baycom_epp.c: In function ‘epp_bh’:
../drivers/net/hamradio/baycom_epp.c:630:6: error: implicit declaration of function ‘boot_cpu_has’; did you mean ‘get_cpu_mask’? [-Werror=implicit-function-declaration]
  if (boot_cpu_has(X86_FEATURE_TSC))   \
      ^
../drivers/net/hamradio/baycom_epp.c:658:2: note: in expansion of macro ‘GETTICK’
  GETTICK(time1);

Fixes: 68f5d3f3b654 ("um: add PCI over virtio emulation driver")
Signed-off-by: Randy Dunlap <rdunlap at infradead.org>
Cc: linux-um at lists.infradead.org
Cc: Jeff Dike <jdike at addtoit.com>
Cc: Richard Weinberger <richard at nod.at>
Cc: Anton Ivanov <anton.ivanov at cambridgegreys.com>
Cc: "David S. Miller" <davem at davemloft.net>
Cc: Jakub Kicinski <kuba at kernel.org>
Cc: Thomas Sailer <t.sailer at alumni.ethz.ch>
Cc: linux-hams at vger.kernel.org
---
 drivers/net/hamradio/baycom_epp.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- linux-next-20211013.orig/drivers/net/hamradio/baycom_epp.c
+++ linux-next-20211013/drivers/net/hamradio/baycom_epp.c
@@ -623,16 +623,16 @@ static int receive(struct net_device *de
 
 /* --------------------------------------------------------------------- */
 
-#ifdef __i386__
+#if defined(__i386__) && !defined(CONFIG_UML)
 #include <asm/msr.h>
 #define GETTICK(x)						\
 ({								\
 	if (boot_cpu_has(X86_FEATURE_TSC))			\
 		x = (unsigned int)rdtsc();			\
 })
-#else /* __i386__ */
+#else /* __i386__  && !CONFIG_UML */
 #define GETTICK(x)
-#endif /* __i386__ */
+#endif /* __i386__  && !CONFIG_UML */
 
 static void epp_bh(struct work_struct *work)
 {