linux-kernel - [PATCH v3] x86/tsc: Disable clocksource watchdog for TSC on recent UV

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-ID: <aKYn6I8kpxMFnVOP@hpe.com>
Date: Wed, 20 Aug 2025 14:54:16 -0500
From: Dimitri Sivanich <sivanich@....com>
To: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Cc: Jiri Wiesner <jwiesner@...e.de>, Thomas Gleixner <tglx@...utronix.de>,
        Jonathan Corbet <corbet@....net>, Steve Wahl <steve.wahl@....com>,
        Justin Ernst <justin.ernst@....com>, Kyle Meyer <kyle.meyer@....com>,
        Russ Anderson <russ.anderson@....com>, Ingo Molnar <mingo@...hat.com>,
        Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>
Subject: [PATCH v3] x86/tsc: Disable clocksource watchdog for TSC on recent UV

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@....com>
---

Version 3:  Fixes a build error in the X86 32-bit build.

Version 2:  Fixes a build error that occurs when UV is not configured.

 arch/x86/include/asm/uv/uv.h     | 3 +++
 arch/x86/include/asm/uv/uv_hub.h | 2 ++
 arch/x86/kernel/tsc.c            | 3 ++-
 3 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/uv/uv.h b/arch/x86/include/asm/uv/uv.h
index 648eb23fe7f0..f1aebdf85e68 100644
--- a/arch/x86/include/asm/uv/uv.h
+++ b/arch/x86/include/asm/uv/uv.h
@@ -38,6 +38,9 @@ static inline int is_uv_system(void)	{ return 0; }
 static inline int is_uv_hubbed(int uv)	{ return 0; }
 static inline void uv_cpu_init(void)	{ }
 static inline void uv_system_init(void)	{ }
+static inline int is_uvx_hub(void) { return 0; }
+static inline int is_uvy_hub(void) { return 0; }
+static inline int is_uv_hub(void) { return 0; }
 
 #endif	/* X86_UV */
 
diff --git a/arch/x86/include/asm/uv/uv_hub.h b/arch/x86/include/asm/uv/uv_hub.h
index ea877fd83114..6e085ce8fc02 100644
--- a/arch/x86/include/asm/uv/uv_hub.h
+++ b/arch/x86/include/asm/uv/uv_hub.h
@@ -246,6 +246,7 @@ static inline int is_uv5_hub(void) { return is_uv(UV5); }
  * then test if is UV4.
  */
 
+#ifdef CONFIG_X86_UV
 /* UVX class: UV2,3,4 */
 static inline int is_uvx_hub(void) { return is_uv(UVX); }
 
@@ -254,6 +255,7 @@ static inline int is_uvy_hub(void) { return is_uv(UVY); }
 
 /* Any UV Hubbed System */
 static inline int is_uv_hub(void) { return is_uv(UV_ANY); }
+#endif
 
 union uvh_apicid {
     unsigned long       v;
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 87e749106dda..a9f97d423ab0 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -32,6 +32,7 @@
 #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 +1262,7 @@ 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