Merge tag 'x86_fred_for_v7.1_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

e9635f2a · Linus Torvalds <[email protected]> · 2026-04-14 14:50:51 -07:00

Pull x86 FRED updates from Borislav Petkov:
 "We made the FRED support an opt-in initially out of fear of it
  breaking machines left and right in the case of a hw bug in the first
  generation of machines supporting it.

  Now that that the FRED code has seen a lot of hammering, flip the
  logic to be opt-out as is the usual case with new hw features"

* tag 'x86_fred_for_v7.1_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/fred: Remove kernel log message when initializing exceptions
  x86/fred: Enable FRED by default

Commit: e9635f2a73604ad9cb33d480b489a03bdd03329f
Parents: fabd5a8d · f0958d58

Merge commit. Changes below are compared with the first parent: fabd5a8d.

Changes

4 files changed · +4 −7

File	Status	Add	Del	Content
Documentation/admin-guide/kernel-parameters.txt	modified	+2	−2	View file
arch/x86/Kconfig	modified	+1	−1	View file
arch/x86/kernel/cpu/common.c	modified	+1	−1	View file
arch/x86/kernel/fred.c	modified	+0	−3	View file

Documentation/admin-guide/kernel-parameters.txt

View file

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 291f4da..f2ce1f4 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1765,8 +1765,8 @@ Kernel parameters
 	fred=		[X86-64]
 			Enable/disable Flexible Return and Event Delivery.
 			Format: { on | off }
-			on: enable FRED when it's present.
-			off: disable FRED, the default setting.
+			on: enable FRED when it's present, the default setting.
+			off: disable FRED.
 
 	ftrace=[tracer]
 			[FTRACE] will set and start the specified tracer

arch/x86/Kconfig

View file

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 733f509..0b5f30d 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -554,7 +554,7 @@ config X86_FRED
 	bool "Flexible Return and Event Delivery"
 	depends on X86_64
 	help
-	  When enabled, try to use Flexible Return and Event Delivery
+	  When enabled, use Flexible Return and Event Delivery
 	  instead of the legacy SYSCALL/SYSENTER/IDT architecture for
 	  ring transitions and exception/interrupt handling if the
 	  system supports it.

arch/x86/kernel/cpu/common.c

View file

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 8060ccc..4e1f0c4 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1761,7 +1761,7 @@ static void __init cpu_parse_early_param(void)
 
 	/* Minimize the gap between FRED is available and available but disabled. */
 	arglen = cmdline_find_option(boot_command_line, "fred", arg, sizeof(arg));
-	if (arglen != 2 || strncmp(arg, "on", 2))
+	if (arglen == 3 && !strncmp(arg, "off", 3))
 		setup_clear_cpu_cap(X86_FEATURE_FRED);
 
 	arglen = cmdline_find_option(boot_command_line, "clearcpuid", arg, sizeof(arg));

arch/x86/kernel/fred.c

View file

diff --git a/arch/x86/kernel/fred.c b/arch/x86/kernel/fred.c
index e736b19..117aa06 100644
--- a/arch/x86/kernel/fred.c
+++ b/arch/x86/kernel/fred.c
@@ -27,9 +27,6 @@ EXPORT_PER_CPU_SYMBOL(fred_rsp0);
 
 void cpu_init_fred_exceptions(void)
 {
-	/* When FRED is enabled by default, remove this log message */
-	pr_info("Initialize FRED on CPU%d\n", smp_processor_id());
-
 	/*
 	 * If a kernel event is delivered before a CPU goes to user level for
 	 * the first time, its SS is NULL thus NULL is pushed into the SS field