linux-kernel - Re: [PATCH 2/3] [x86, next] Add mce_ser interface in /sys/kernel/debug/mce/ for test

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Date:	Fri, 29 Oct 2010 10:06:51 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Jin Dongming <jin.dongming@...css.fujitsu.com>
Cc:	Huang Ying <ying.huang@...el.com>, Ingo Molnar <mingo@...e.hu>,
	"H.Peter Anvin" <hpa@...or.com>, Andi Kleen <andi@...stfloor.org>,
	Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>,
	LKLM <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/3] [x86, next] Add mce_ser interface in
 /sys/kernel/debug/mce/ for test

On Fri, Oct 29, 2010 at 01:42:09PM +0900, Jin Dongming wrote:
> If we want to test the part of mce handler for SRAO and SRAR,  we need to
> have a test machine whose CPU supports MCG_SER_P. If we don't have such
> machine, we can not test the part of mce handler for SRAO and SRAR.
> 
> With this interface we can test the part of mce handler for SRAO and SRAR
> by setting mce_ser 1 on the machine which does not support MCG_SER_P.
> 
> Usage:
>         if val == 1 or val == 0
>            Set val to mce_ser.
>         else
>            Ser the original value to mce_ser.
> 
> Note:
>     Please don't use mce_ser interface except mce test.
>     Because when the real mce exception happened, the unsuitable set
>     with this interface maybe change the real process of mce handler and
>     lead to a different result.

Basic idea is good (I have been using a similar patch for quite some time).
My patch was a little bit simpler though, not bothering with org_ser:

---

MCE: Add an debugfs interface to force MCA recovery

This is useful to run the MCA recovery test cases using
error injection on a non MCA recovery capable system.

On a system without MCA recovery this should be a nop.

Signed-off-by: Andi Kleen <ak@...ux.intel.com>

---
 arch/x86/kernel/cpu/mcheck/mce.c |   20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

Index: linux/arch/x86/kernel/cpu/mcheck/mce.c
===================================================================
--- linux.orig/arch/x86/kernel/cpu/mcheck/mce.c
+++ linux/arch/x86/kernel/cpu/mcheck/mce.c
@@ -2346,13 +2346,26 @@ static int fake_panic_set(void *data, u6
 	fake_panic = val;
 	return 0;
 }
+static int mca_recovery_get(void *data, u64 *val)
+{
+	*val = mce_ser;
+	return 0;
+}
+
+static int mca_recovery_set(void *data, u64 val)
+{
+	mce_ser = val;
+	return 0;
+}
 
 DEFINE_SIMPLE_ATTRIBUTE(fake_panic_fops, fake_panic_get,
 			fake_panic_set, "%llu\n");
+DEFINE_SIMPLE_ATTRIBUTE(mca_recovery_fops, mca_recovery_get,
+			mca_recovery_set, "%llu\n");
 
 static int __init mcheck_debugfs_init(void)
 {
-	struct dentry *dmce, *ffake_panic;
+	struct dentry *dmce, *ffake_panic, *fmca_recovery;
 
 	dmce = mce_get_debugfs_dir();
 	if (!dmce)
@@ -2361,7 +2374,10 @@ static int __init mcheck_debugfs_init(vo
 					  &fake_panic_fops);
 	if (!ffake_panic)
 		return -ENOMEM;
-
+	fmca_recovery = debugfs_create_file("mca_recovery_force",0644,dmce,NULL,
+					&mca_recovery_fops);
+	if (!fmca_recovery)
+		return -ENOMEM;
 	return 0;
 }
 late_initcall(mcheck_debugfs_init);
--
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