[MODERATED] [PATCH v7 07/10] TAAv7 7

From: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
To: speck@linutronix.de
Subject: [MODERATED] [PATCH v7 07/10] TAAv7 7
Date: Mon, 21 Oct 2019 13:29:02 -0700	[thread overview]
Message-ID: <=?utf-8?q?=3C188a762ef941a866da7ac597981b3a425e0f7e70=2E157168?= =?utf-8?q?8957=2Egit=2Epawan=2Ekumar=2Egupta=40linux=2Eintel=2Ecom=3E?=> (raw)
In-Reply-To: <cover.1571688957.git.pawan.kumar.gupta@linux.intel.com>

From: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Subject: [PATCH v7 07/10] x86/tsx: Add "auto" option to TSX cmdline parameter

Platforms which are not affected by X86_BUG_TAA may want the TSX feature
enabled. Add "auto" option to the TSX cmdline parameter. When tsx=auto
disable TSX when X86_BUG_TAA is present, otherwise enable TSX.

More details on X86_BUG_TAA can be found here:
https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/tsx_async_abort.html

Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Tested-by: Neelima Krishnan <neelima.krishnan@intel.com>
---
 Documentation/admin-guide/kernel-parameters.txt | 5 +++++
 arch/x86/kernel/cpu/tsx.c                       | 5 +++++
 2 files changed, 10 insertions(+)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index ad6b69057bb0..4d63dc8dc2fc 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -4856,6 +4856,11 @@
 
 			on	- Enable TSX on the system.
 			off	- Disable TSX on the system.
+			auto	- Disable TSX if X86_BUG_TAA is present,
+				  otherwise enable TSX on the system.
+
+			More details on X86_BUG_TAA are here:
+			Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
 
 			Not specifying this option is equivalent to tsx=off.
 
diff --git a/arch/x86/kernel/cpu/tsx.c b/arch/x86/kernel/cpu/tsx.c
index d031a8b6fb0e..9d7d3ad324b7 100644
--- a/arch/x86/kernel/cpu/tsx.c
+++ b/arch/x86/kernel/cpu/tsx.c
@@ -79,6 +79,11 @@ void __init tsx_init(void)
 			tsx_ctrl_state = TSX_CTRL_ENABLE;
 		} else if (!strcmp(arg, "off")) {
 			tsx_ctrl_state = TSX_CTRL_DISABLE;
+		} else if (!strcmp(arg, "auto")) {
+			if (boot_cpu_has_bug(X86_BUG_TAA))
+				tsx_ctrl_state = TSX_CTRL_DISABLE;
+			else
+				tsx_ctrl_state = TSX_CTRL_ENABLE;
 		} else {
 			tsx_ctrl_state = TSX_CTRL_DISABLE;
 			pr_err("tsx: invalid option, defaulting to off\n");
-- 
2.20.1
