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Commit d3d6923c authored by Borislav Petkov's avatar Borislav Petkov Committed by Thomas Gleixner
Browse files

x86/mce: Carve out the crashing_cpu check 



Carve out the rendezvous handler timeout avoidance check into a separate
function in order to simplify the #MC handler.

No functional changes.

Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20180622095428.626-4-bp@alien8.de
parent bc39f010

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

+37 −27
Original line number Diff line number Diff line
@@ -1104,6 +1104,34 @@ static void mce_unmap_kpfn(unsigned long pfn) 
}

#endif





/*

 * Cases where we avoid rendezvous handler timeout:

 * 1) If this CPU is offline.

 *

 * 2) If crashing_cpu was set, e.g. we're entering kdump and we need to

 *  skip those CPUs which remain looping in the 1st kernel - see

 *  crash_nmi_callback().

 *

 * Note: there still is a small window between kexec-ing and the new,

 * kdump kernel establishing a new #MC handler where a broadcasted MCE

 * might not get handled properly.

 */

static bool __mc_check_crashing_cpu(int cpu)

{

	if (cpu_is_offline(cpu) ||

	    (crashing_cpu != -1 && crashing_cpu != cpu)) {

		u64 mcgstatus;



		mcgstatus = mce_rdmsrl(MSR_IA32_MCG_STATUS);

		if (mcgstatus & MCG_STATUS_RIPV) {

			mce_wrmsrl(MSR_IA32_MCG_STATUS, 0);

			return true;

		}

	}

	return false;

}



/*

 * The actual machine check handler. This only handles real

 * exceptions when something got corrupted coming in through int 18.
@@ -1118,60 +1146,42 @@ static void mce_unmap_kpfn(unsigned long pfn) 
 */

void do_machine_check(struct pt_regs *regs, long error_code)

{

	DECLARE_BITMAP(valid_banks, MAX_NR_BANKS);

	DECLARE_BITMAP(toclear, MAX_NR_BANKS);

	struct mca_config *cfg = &mca_cfg;

	int cpu = smp_processor_id();

	char *msg = "Unknown";

	struct mce m, *final;

	int i;

	int worst = 0;

	int severity;

	int i;



	/*

	 * Establish sequential order between the CPUs entering the machine

	 * check handler.

	 */

	int order = -1;



	/*

	 * If no_way_out gets set, there is no safe way to recover from this

	 * MCE.  If mca_cfg.tolerant is cranked up, we'll try anyway.

	 */

	int no_way_out = 0;



	/*

	 * If kill_it gets set, there might be a way to recover from this

	 * error.

	 */

	int kill_it = 0;

	DECLARE_BITMAP(toclear, MAX_NR_BANKS);

	DECLARE_BITMAP(valid_banks, MAX_NR_BANKS);

	char *msg = "Unknown";



	/*

	 * MCEs are always local on AMD. Same is determined by MCG_STATUS_LMCES

	 * on Intel.

	 */

	int lmce = 1;

	int cpu = smp_processor_id();



	/*

	 * Cases where we avoid rendezvous handler timeout:

	 * 1) If this CPU is offline.

	 *

	 * 2) If crashing_cpu was set, e.g. we're entering kdump and we need to

	 *  skip those CPUs which remain looping in the 1st kernel - see

	 *  crash_nmi_callback().

	 *

	 * Note: there still is a small window between kexec-ing and the new,

	 * kdump kernel establishing a new #MC handler where a broadcasted MCE

	 * might not get handled properly.

	 */

	if (cpu_is_offline(cpu) ||

	    (crashing_cpu != -1 && crashing_cpu != cpu)) {

		u64 mcgstatus;



		mcgstatus = mce_rdmsrl(MSR_IA32_MCG_STATUS);

		if (mcgstatus & MCG_STATUS_RIPV) {

			mce_wrmsrl(MSR_IA32_MCG_STATUS, 0);

	if (__mc_check_crashing_cpu(cpu))

		return;

		}

	}



	ist_enter(regs);