[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 added a call to tsc_early_init() which initializes the TSC ADJUST
values before acpi_boot_table_init().  In the case of UV systems,
that is a necessary step thats calls uv_system_init().  This informs
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 the early tsc initialization on UV systems and let TSC
init tests take place later in tsc_init().

Fixes: cf7a63ef4e02 ("x86/tsc: Calibrate tsc only once") 
Signed-off-by: Mike Travis <mike.travis@hpe.com>
Suggested-by: Hedi Berriche <hedi.berriche@hpe.com>
Reviewed-by: Russ Anderson <rja@hpe.com>
Reviewed-by: Dimitri Sivanich <sivanich@hpe.com>
---
 arch/x86/kernel/tsc.c |    4 ++++
 1 file changed, 4 insertions(+)

--- linux.orig/arch/x86/kernel/tsc.c
+++ linux/arch/x86/kernel/tsc.c
@@ -26,6 +26,7 @@
 #include <asm/apic.h>
 #include <asm/intel-family.h>
 #include <asm/i8259.h>
+#include <asm/uv/uv.h>
 
 unsigned int __read_mostly cpu_khz;	/* TSC clocks / usec, not used here */
 EXPORT_SYMBOL(cpu_khz);
@@ -1433,6 +1434,9 @@ void __init tsc_early_init(void)
 {
 	if (!boot_cpu_has(X86_FEATURE_TSC))
 		return;
+	/* Don't change UV TSC multi-chassis synchronization */
+	if (is_early_uv_system())
+		return;
 	if (!determine_cpu_tsc_frequencies(true))
 		return;
 	loops_per_jiffy = get_loops_per_jiffy();

--