x86/xen: Fix secondary processors' FPU initialization

commit fe3e0a13e5 upstream.

Moving the call of fpu__init_cpu() from cpu_init() to start_secondary()
broke Xen PV guests, as those don't call start_secondary() for APs.

Call fpu__init_cpu() in Xen's cpu_bringup(), which is the Xen PV
replacement of start_secondary().

Fixes: b81fac906a ("x86/fpu: Move FPU initialization into arch_cpu_finalize_init()")
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20230703130032.22916-1-jgross@suse.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/x86/xen/smp_pv.c

@@ -30,6 +30,7 @@
 #include <asm/desc.h>
 #include <asm/cpu.h>
 #include <asm/io_apic.h>
+#include <asm/fpu/internal.h>
 
 #include <xen/interface/xen.h>
 #include <xen/interface/vcpu.h>
@@ -63,6 +64,7 @@ static void cpu_bringup(void)
 
 	cr4_init();
 	cpu_init();
+	fpu__init_cpu();
 	touch_softlockup_watchdog();
 
 	/* PVH runs in ring 0 and allows us to do native syscalls. Yay! */