linux-kernel - Re: [PATCH v2 2/2] x86/tsx: Get the tsx= command line parameter with early

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Message-ID: <20251010003345.dc6ybdhwoslyse5m@desk>
Date: Thu, 9 Oct 2025 17:33:45 -0700
From: Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
To: Petr Tesarik <ptesarik@...e.com>
Cc: "H. Peter Anvin" <hpa@...or.com>, Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>,
	"open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/2] x86/tsx: Get the tsx= command line parameter with
 early_param()

On Thu, Oct 09, 2025 at 11:51:40AM -0700, Pawan Gupta wrote:
> On Fri, Sep 26, 2025 at 08:01:02PM +0200, Petr Tesarik wrote:
> > Use early_param() to get the value of the tsx= command line parameter.
> > Although cmdline_find_option() works fine, the option is later reported
> > as unknown and passed to user space. The latter is not a real issue, but
> > the former is confusing and makes people wonder if the tsx= parameter had
> > any effect and double-check for typos unnecessarily.

If this is too much of an annoyance, I would suggest to move
x86_get_tsx_auto_mode() from tsx_parse_cmdline() to tsx_init().

---
diff --git a/arch/x86/kernel/cpu/tsx.c b/arch/x86/kernel/cpu/tsx.c
index 167dfd38b87a..805be8beb37a 100644
--- a/arch/x86/kernel/cpu/tsx.c
+++ b/arch/x86/kernel/cpu/tsx.c
@@ -20,6 +20,7 @@
 #define pr_fmt(fmt) "tsx: " fmt
 
 enum tsx_ctrl_states {
+	TSX_CTRL_AUTO,
 	TSX_CTRL_ENABLE,
 	TSX_CTRL_DISABLE,
 	TSX_CTRL_RTM_ALWAYS_ABORT,
@@ -27,7 +28,8 @@ enum tsx_ctrl_states {
 };
 
 static enum tsx_ctrl_states tsx_ctrl_state __ro_after_init =
-	TSX_CTRL_NOT_SUPPORTED;
+	IS_ENABLED(CONFIG_X86_INTEL_TSX_MODE_AUTO) ? TSX_CTRL_AUTO :
+	IS_ENABLED(CONFIG_X86_INTEL_TSX_MODE_OFF)  ? TSX_CTRL_DISABLE : TSX_CTRL_ENABLE;
 
 static void tsx_disable(void)
 {
@@ -164,11 +166,28 @@ static void tsx_dev_mode_disable(void)
 	}
 }
 
-void __init tsx_init(void)
+static int __init tsx_parse_cmdline(char *str)
 {
-	char arg[5] = {};
-	int ret;
+	if (!str)
+		return -EINVAL;
+
+	if (!strcmp(str, "on")) {
+		tsx_ctrl_state = TSX_CTRL_ENABLE;
+	} else if (!strcmp(str, "off")) {
+		tsx_ctrl_state = TSX_CTRL_DISABLE;
+	} else if (!strcmp(str, "auto")) {
+		tsx_ctrl_state = TSX_CTRL_AUTO;
+	} else {
+		tsx_ctrl_state = TSX_CTRL_DISABLE;
+		pr_err("invalid option, defaulting to off\n");
+	}
+
+	return 0;
+}
+early_param("tsx", tsx_parse_cmdline);
 
+void __init tsx_init(void)
+{
 	tsx_dev_mode_disable();
 
 	/*
@@ -202,27 +221,8 @@ void __init tsx_init(void)
 		return;
 	}
 
-	ret = cmdline_find_option(boot_command_line, "tsx", arg, sizeof(arg));
-	if (ret >= 0) {
-		if (!strcmp(arg, "on")) {
-			tsx_ctrl_state = TSX_CTRL_ENABLE;
-		} else if (!strcmp(arg, "off")) {
-			tsx_ctrl_state = TSX_CTRL_DISABLE;
-		} else if (!strcmp(arg, "auto")) {
-			tsx_ctrl_state = x86_get_tsx_auto_mode();
-		} else {
-			tsx_ctrl_state = TSX_CTRL_DISABLE;
-			pr_err("invalid option, defaulting to off\n");
-		}
-	} else {
-		/* tsx= not provided */
-		if (IS_ENABLED(CONFIG_X86_INTEL_TSX_MODE_AUTO))
-			tsx_ctrl_state = x86_get_tsx_auto_mode();
-		else if (IS_ENABLED(CONFIG_X86_INTEL_TSX_MODE_OFF))
-			tsx_ctrl_state = TSX_CTRL_DISABLE;
-		else
-			tsx_ctrl_state = TSX_CTRL_ENABLE;
-	}
+	if (tsx_ctrl_state == TSX_CTRL_AUTO)
+		tsx_ctrl_state = x86_get_tsx_auto_mode();
 
 	if (tsx_ctrl_state == TSX_CTRL_DISABLE) {
 		tsx_disable();