linux-kernel - Re: [PATCH] x86/MCE: Remove MCP

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Date:   Tue, 8 Nov 2016 22:54:52 +0100 (CET)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Borislav Petkov <bp@...en8.de>
cc:     "Luck, Tony" <tony.luck@...el.com>,
        linux-edac <linux-edac@...r.kernel.org>, X86 ML <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86/MCE: Remove MCP_TIMESTAMP

On Tue, 8 Nov 2016, Borislav Petkov wrote:

> On Tue, Nov 08, 2016 at 10:14:04PM +0100, Thomas Gleixner wrote:
> > And yes, you should spend the extra cycles. Adding a flags argument to
> > mce_setup() and propagate it through the various callsites shouldn't be
> > that hard and would make the stuff obvious instead of obfuscated.
> 
> Sure, that's already on my TODO. I want to take a look at it when I have
> a quiet moment.

So for now we should fold something like the below into this patch.

Thanks,

	tglx

8<--------------------

--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -706,6 +706,15 @@ bool machine_check_poll(enum mcp_flags f
 
 	mce_gather_info(&m, NULL);
 
+	/*
+	 * m.tsc was set in mce_setup(). Clear it if not requested.
+	 *
+	 * FIXME: Propagate @flags to mce_gather_info/mce_setup() to avoid
+	 *	  that dance
+	 */
+	if (!(flags & MCP_TIMESTAMP))
+		m.tsc = 0;
+
 	for (i = 0; i < mca_cfg.banks; i++) {
 		if (!mce_banks[i].ctl || !test_bit(i, *b))
 			continue;
@@ -734,9 +743,6 @@ bool machine_check_poll(enum mcp_flags f
 
 		mce_read_aux(&m, i);
 
-		if (!(flags & MCP_TIMESTAMP))
-			m.tsc = 0;
-
 		severity = mce_severity(&m, mca_cfg.tolerant, NULL, false);
 
 		if (severity == MCE_DEFERRED_SEVERITY && memory_error(&m))