[PATCH] x86/tsc: Disable clocksource watchdog for TSC on recent UV

[PATCH] x86/tsc: Disable clocksource watchdog for TSC on recent UV

[Dimitri Sivanich]

Disable clocksource watchdog checking on recent and future UV platforms
to avoid false positives.

Commits 'b50db7095fe0 ("x86/tsc: Disable clocksource watchdog for TSC on
qualified platforms")' and '233756a640be ("Extend watchdog check exemption
to 4-Sockets platform")' were introduced to avoid an issue where the TSC
is falsely declared unstable by exempting qualified platforms of up to
4-sockets from TSC clocksource watchdog checking.  Extend that exemption
to include recent and future UV platforms.

Signed-off-by: Dimitri Sivanich <sivanich@hpe.com>
---
 arch/x86/kernel/tsc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 87e749106dda..23727d7214e6 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -31,7 +31,7 @@
 #include <asm/i8259.h>
 #include <asm/msr.h>
 #include <asm/topology.h>
-#include <asm/uv/uv.h>
+#include <asm/uv/uv_hub.h>
 #include <asm/sev.h>
 
 unsigned int __read_mostly cpu_khz;	/* TSC clocks / usec, not used here */
@@ -1261,7 +1261,7 @@ static void __init check_system_tsc_reliable(void)
 	if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC) &&
 	    boot_cpu_has(X86_FEATURE_NONSTOP_TSC) &&
 	    boot_cpu_has(X86_FEATURE_TSC_ADJUST) &&
-	    topology_max_packages() <= 4)
+	    (topology_max_packages() <= 4 || is_uvy_hub()))
 		tsc_disable_clocksource_watchdog();
 }
 
-- 
2.43.0

Re: [PATCH] x86/tsc: Disable clocksource watchdog for TSC on recent UV

[kernel test robot]

Hi Dimitri,

kernel test robot noticed the following build errors:

[auto build test ERROR on tip/x86/core]
[also build test ERROR on tip/master linus/master v6.16 next-20250731]
[cannot apply to tip/auto-latest]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Dimitri-Sivanich/x86-tsc-Disable-clocksource-watchdog-for-TSC-on-recent-UV/20250731-053059
base:   tip/x86/core
patch link:    https://lore.kernel.org/r/aIqKYdvlKlBlSoQK%40hpe.com
patch subject: [PATCH] x86/tsc: Disable clocksource watchdog for TSC on recent UV
config: x86_64-allnoconfig (https://download.01.org/0day-ci/archive/20250731/202507311627.rt0PViwZ-lkp@intel.com/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250731/202507311627.rt0PViwZ-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202507311627.rt0PViwZ-lkp@intel.com/

All errors (new ones prefixed by >>):

>> ld.lld: error: undefined symbol: __uv_cpu_info
   >>> referenced by tsc.c
   >>>               arch/x86/kernel/tsc.o:(check_system_tsc_reliable) in archive vmlinux.a

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki