x86/mce: Stop mce_reign() from re-computing severity for every CPU (13c877f4) · Commits · 戴 / test

Back in commit: ("x86/mce: Reuse one of the u16 padding fields in 'struct mce'") a field was added to "struct mce" to save the computed error severity. Make use of this in mce_reign() to avoid re-computing the severity for every CPU. In the case where the machine panics, one call to mce_severity() is still needed in order to provide the correct message giving the reason for the panic. Signed-off-by:

Tony Luck <tony.luck@intel.com> Signed-off-by:

Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20200908175519.14223-2-tony.luck@intel.com

arch/x86/kernel/cpu/mce/core.c

+8 −8

Original line number	Diff line number	Diff line
		@@ -920,7 +920,6 @@ static void mce_reign(void)
		struct mce *m = NULL;
		int global_worst = 0;
		char *msg = NULL;
		char *nmsg = NULL;

		/*
		* This CPU is the Monarch and the other CPUs have run
		@@ -928,12 +927,10 @@ static void mce_reign(void)
		* Grade the severity of the errors of all the CPUs.
		*/
		for_each_possible_cpu(cpu) {
		int severity = mce_severity(&per_cpu(mces_seen, cpu),
		mca_cfg.tolerant,
		&nmsg, true);
		if (severity > global_worst) {
		msg = nmsg;
		global_worst = severity;
		struct mce *mtmp = &per_cpu(mces_seen, cpu);

		if (mtmp->severity > global_worst) {
		global_worst = mtmp->severity;
		m = &per_cpu(mces_seen, cpu);
		}
		}
		@@ -943,8 +940,11 @@ static void mce_reign(void)
		* This dumps all the mces in the log buffer and stops the
		* other CPUs.
		*/
		if (m && global_worst >= MCE_PANIC_SEVERITY && mca_cfg.tolerant < 3)
		if (m && global_worst >= MCE_PANIC_SEVERITY && mca_cfg.tolerant < 3) {
		/* call mce_severity() to get "msg" for panic */
		mce_severity(m, mca_cfg.tolerant, &msg, true);
		mce_panic("Fatal machine check", m, msg);
		}

		/*
		* For UC somewhere we let the CPU who detects it handle it.

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