Commit 70c459d9 authored by Carlos Bilbao's avatar Carlos Bilbao Committed by Borislav Petkov
Browse files

x86/mce: Simplify AMD severity grading logic 



The MCE handler needs to understand the severity of the machine errors to
act accordingly. Simplify the AMD grading logic following a logic that
closely resembles the descriptions of the public PPR documents. This will
help include more fine-grained grading of errors in the future.

  [ bp: Touchups. ]

Signed-off-by: default avatarCarlos Bilbao <carlos.bilbao@amd.com>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Reviewed-by: default avatarYazen Ghannam <yazen.ghannam@amd.com>
Link: https://lore.kernel.org/r/20220405183212.354606-2-carlos.bilbao@amd.com
parent e5f28623

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

+36 −65
Original line number Diff line number Diff line
@@ -301,85 +301,56 @@ static noinstr int error_context(struct mce *m, struct pt_regs *regs) 
	}

}



static __always_inline int mce_severity_amd_smca(struct mce *m, enum context err_ctx)

/* See AMD PPR(s) section Machine Check Error Handling. */

static noinstr int mce_severity_amd(struct mce *m, struct pt_regs *regs, char **msg, bool is_excp)

{

	u64 mcx_cfg;

	int ret;



	/*

	 * We need to look at the following bits:

	 * - "succor" bit (data poisoning support), and

	 * - TCC bit (Task Context Corrupt)

	 * in MCi_STATUS to determine error severity.

	 * Default return value: Action required, the error must be handled

	 * immediately.

	 */

	if (!mce_flags.succor)

		return MCE_PANIC_SEVERITY;

	ret = MCE_AR_SEVERITY;



	mcx_cfg = mce_rdmsrl(MSR_AMD64_SMCA_MCx_CONFIG(m->bank));



	/* TCC (Task context corrupt). If set and if IN_KERNEL, panic. */

	if ((mcx_cfg & MCI_CONFIG_MCAX) &&

	    (m->status & MCI_STATUS_TCC) &&

	    (err_ctx == IN_KERNEL))

		return MCE_PANIC_SEVERITY;

	/* Processor Context Corrupt, no need to fumble too much, die! */

	if (m->status & MCI_STATUS_PCC) {

		ret = MCE_PANIC_SEVERITY;

		goto out;

	}



	 /* ...otherwise invoke hwpoison handler. */

	return MCE_AR_SEVERITY;

	if (m->status & MCI_STATUS_DEFERRED) {

		ret = MCE_DEFERRED_SEVERITY;

		goto out;

	}



	/*

 * See AMD Error Scope Hierarchy table in a newer BKDG. For example

 * 49125_15h_Models_30h-3Fh_BKDG.pdf, section "RAS Features"

	 * If the UC bit is not set, the system either corrected or deferred

	 * the error. No action will be required after logging the error.

	 */

static noinstr int mce_severity_amd(struct mce *m, struct pt_regs *regs, char **msg, bool is_excp)

{

	enum context ctx = error_context(m, regs);



	/* Processor Context Corrupt, no need to fumble too much, die! */

	if (m->status & MCI_STATUS_PCC)

		return MCE_PANIC_SEVERITY;



	if (m->status & MCI_STATUS_UC) {



		if (ctx == IN_KERNEL)

			return MCE_PANIC_SEVERITY;

	if (!(m->status & MCI_STATUS_UC)) {

		ret = MCE_KEEP_SEVERITY;

		goto out;

	}



	/*

		 * On older systems where overflow_recov flag is not present, we

		 * should simply panic if an error overflow occurs. If

		 * overflow_recov flag is present and set, then software can try

		 * to at least kill process to prolong system operation.

	 * On MCA overflow, without the MCA overflow recovery feature the

	 * system will not be able to recover, panic.

	 */

		if (mce_flags.overflow_recov) {

			if (mce_flags.smca)

				return mce_severity_amd_smca(m, ctx);



			/* kill current process */

			return MCE_AR_SEVERITY;

		} else {

			/* at least one error was not logged */

			if (m->status & MCI_STATUS_OVER)

				return MCE_PANIC_SEVERITY;

	if ((m->status & MCI_STATUS_OVER) && !mce_flags.overflow_recov) {

		ret = MCE_PANIC_SEVERITY;

		goto out;

	}



		/*

		 * For any other case, return MCE_UC_SEVERITY so that we log the

		 * error and exit #MC handler.

		 */

		return MCE_UC_SEVERITY;

	if (!mce_flags.succor) {

		ret = MCE_PANIC_SEVERITY;

		goto out;

	}



	/*

	 * deferred error: poll handler catches these and adds to mce_ring so

	 * memory-failure can take recovery actions.

	 */

	if (m->status & MCI_STATUS_DEFERRED)

		return MCE_DEFERRED_SEVERITY;

	if (error_context(m, regs) == IN_KERNEL)

		ret = MCE_PANIC_SEVERITY;



	/*

	 * corrected error: poll handler catches these and passes responsibility

	 * of decoding the error to EDAC

	 */

	return MCE_KEEP_SEVERITY;

out:

	return ret;

}



static noinstr int mce_severity_intel(struct mce *m, struct pt_regs *regs, char **msg, bool is_excp)