[PATCH 2/2] x86/tsc: Fix UV TSC initialization

[Mike Travis <mike.travis@hpe.com>]

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Fix regression introduced by

commit cf7a63ef4e02 ("x86/tsc: Calibrate tsc only once")

as it changed setup_arch() so that it now calls tsc_early_init() before
acpi_boot_table_init() which is a necessary step, in the case of UV
systems, to inform tsc_sanitize_first_cpu() that we're on a platform
with async TSC resets as documented in

commit 341102c3ef29 ("x86/tsc: Add option that TSC on Socket 0 being non-zero is valid")

Fix by skipping tsc_early_init() on UV systems and let TSC initialization
take place later in tsc_init().

Fixes: cf7a63ef4e02 ("x86/tsc: Calibrate tsc only once") 
Signed-off-by: Mike Travis <mike.travis@hpe.com>
Signed-off-by: Hedi Berriche <hedi.berriche@hpe.com>
Reviewed-by: Russ Anderson <rja@hpe.com>
Reviewed-by: Dimitri Sivanich <sivanich@hpe.com>
---
 arch/x86/kernel/setup.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- linux.orig/arch/x86/kernel/setup.c
+++ linux/arch/x86/kernel/setup.c
@@ -117,6 +117,7 @@
 #include <asm/microcode.h>
 #include <asm/kaslr.h>
 #include <asm/unwind.h>
+#include <asm/uv/uv.h>
 
 /*
  * max_low_pfn_mapped: highest direct mapped pfn under 4GB
@@ -1015,7 +1016,10 @@ void __init setup_arch(char **cmdline_p)
 	 */
 	init_hypervisor_platform();
 
-	tsc_early_init();
+	/* UV TSC multi-chassis synchronization already set, don't change it */
+	if (!is_early_uv_system())
+		tsc_early_init();
+
 	x86_init.resources.probe_roms();
 
 	/* after parse_early_param, so could debug it */

--