Commit 6458de97 authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Borislav Petkov
Browse files

x86/mce/amd: Straighten CPU hotplug path 



mce_threshold_create_device() hotplug callback runs on the plugged in
CPU so:

 - use this_cpu_read() which is faster
 - pass in struct threshold_bank **bp to threshold_create_bank() and
   instead of doing per-CPU accesses
 - Use rdmsr_safe() instead of rdmsr_safe_on_cpu() which avoids an IPI.

No functional changes.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200403161943.1458-6-bp@alien8.de
parent 6e7a41c6

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

+15 −17
Original line number Diff line number Diff line
@@ -1223,10 +1223,10 @@ static int allocate_threshold_blocks(unsigned int cpu, struct threshold_bank *tb 
	u32 low, high;

	int err;



	if ((bank >= per_cpu(mce_num_banks, cpu)) || (block >= NR_BLOCKS))

	if ((bank >= this_cpu_read(mce_num_banks)) || (block >= NR_BLOCKS))

		return 0;



	if (rdmsr_safe_on_cpu(cpu, address, &low, &high))

	if (rdmsr_safe(address, &low, &high))

		return 0;



	if (!(high & MASK_VALID_HI)) {
@@ -1316,9 +1316,10 @@ static int __threshold_add_blocks(struct threshold_bank *b) 
	return err;

}



static int threshold_create_bank(unsigned int cpu, unsigned int bank)

static int threshold_create_bank(struct threshold_bank **bp, unsigned int cpu,

				 unsigned int bank)

{

	struct device *dev = per_cpu(mce_device, cpu);

	struct device *dev = this_cpu_read(mce_device);

	struct amd_northbridge *nb = NULL;

	struct threshold_bank *b = NULL;

	const char *name = get_name(bank, NULL);
@@ -1338,7 +1339,7 @@ static int threshold_create_bank(unsigned int cpu, unsigned int bank) 
			if (err)

				goto out;



			per_cpu(threshold_banks, cpu)[bank] = b;

			bp[bank] = b;

			refcount_inc(&b->cpus);



			err = __threshold_add_blocks(b);
@@ -1374,8 +1375,7 @@ static int threshold_create_bank(unsigned int cpu, unsigned int bank) 
	if (err)

		goto out_kobj;



	per_cpu(threshold_banks, cpu)[bank] = b;



	bp[bank] = b;

	return 0;



out_kobj:
@@ -1487,35 +1487,33 @@ int mce_threshold_remove_device(unsigned int cpu) 
 */

int mce_threshold_create_device(unsigned int cpu)

{

	unsigned int bank;

	unsigned int numbanks, bank;

	struct threshold_bank **bp;

	int err;



	if (!mce_flags.amd_threshold)

		return 0;



	bp = per_cpu(threshold_banks, cpu);

	bp = this_cpu_read(threshold_banks);

	if (bp)

		return 0;



	bp = kcalloc(per_cpu(mce_num_banks, cpu), sizeof(struct threshold_bank *),

		     GFP_KERNEL);

	numbanks = this_cpu_read(mce_num_banks);

	bp = kcalloc(numbanks, sizeof(*bp), GFP_KERNEL);

	if (!bp)

		return -ENOMEM;



	per_cpu(threshold_banks, cpu) = bp;



	for (bank = 0; bank < per_cpu(mce_num_banks, cpu); ++bank) {

		if (!(per_cpu(bank_map, cpu) & (1 << bank)))

	for (bank = 0; bank < numbanks; ++bank) {

		if (!(this_cpu_read(bank_map) & (1 << bank)))

			continue;

		err = threshold_create_bank(cpu, bank);

		err = threshold_create_bank(bp, cpu, bank);

		if (err)

			goto out_err;

	}

	this_cpu_write(threshold_banks, bp);



	if (thresholding_irq_en)

		mce_threshold_vector = amd_threshold_interrupt;



	return 0;

out_err:

	mce_threshold_remove_device(cpu);

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