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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: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200403161943.1458-6-bp@alien8.de
This commit is contained in:
Thomas Gleixner 2020-03-30 20:30:45 +02:00 committed by Borislav Petkov
parent 6e7a41c63a
commit 6458de97fc
1 changed files with 15 additions and 17 deletions
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32
arch/x86/kernel/cpu/mce/amd.c
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@ -1223,10 +1223,10 @@ static int allocate_threshold_blocks(unsigned int cpu, struct threshold_bank *tb
u32 low, high; u32 low, high;
int err; 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; return 0;
if (rdmsr_safe_on_cpu(cpu, address, &low, &high)) if (rdmsr_safe(address, &low, &high))
return 0; return 0;
if (!(high & MASK_VALID_HI)) { if (!(high & MASK_VALID_HI)) {
@ -1316,9 +1316,10 @@ static int __threshold_add_blocks(struct threshold_bank *b)
return err; 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 amd_northbridge *nb = NULL;
struct threshold_bank *b = NULL; struct threshold_bank *b = NULL;
const char *name = get_name(bank, 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) if (err)
goto out; goto out;
per_cpu(threshold_banks, cpu)[bank] = b; bp[bank] = b;
refcount_inc(&b->cpus); refcount_inc(&b->cpus);
err = __threshold_add_blocks(b); err = __threshold_add_blocks(b);
@ -1374,8 +1375,7 @@ static int threshold_create_bank(unsigned int cpu, unsigned int bank)
if (err) if (err)
goto out_kobj; goto out_kobj;
per_cpu(threshold_banks, cpu)[bank] = b; bp[bank] = b;
return 0; return 0;
out_kobj: out_kobj:
@ -1487,35 +1487,33 @@ int mce_threshold_remove_device(unsigned int cpu)
*/ */
int mce_threshold_create_device(unsigned int cpu) int mce_threshold_create_device(unsigned int cpu)
{ {
unsigned int bank; unsigned int numbanks, bank;
struct threshold_bank **bp; struct threshold_bank **bp;
int err; int err;
if (!mce_flags.amd_threshold) if (!mce_flags.amd_threshold)
return 0; return 0;
bp = per_cpu(threshold_banks, cpu); bp = this_cpu_read(threshold_banks);
if (bp) if (bp)
return 0; return 0;
bp = kcalloc(per_cpu(mce_num_banks, cpu), sizeof(struct threshold_bank *), numbanks = this_cpu_read(mce_num_banks);
GFP_KERNEL); bp = kcalloc(numbanks, sizeof(*bp), GFP_KERNEL);
if (!bp) if (!bp)
return -ENOMEM; return -ENOMEM;
per_cpu(threshold_banks, cpu) = bp; for (bank = 0; bank < numbanks; ++bank) {
if (!(this_cpu_read(bank_map) & (1 << bank)))
for (bank = 0; bank < per_cpu(mce_num_banks, cpu); ++bank) {
if (!(per_cpu(bank_map, cpu) & (1 << bank)))
continue; continue;
err = threshold_create_bank(cpu, bank); err = threshold_create_bank(bp, cpu, bank);
if (err) if (err)
goto out_err; goto out_err;
} }
this_cpu_write(threshold_banks, bp);
if (thresholding_irq_en) if (thresholding_irq_en)
mce_threshold_vector = amd_threshold_interrupt; mce_threshold_vector = amd_threshold_interrupt;
return 0; return 0;
out_err: out_err:
mce_threshold_remove_device(cpu); mce_threshold_remove_device(cpu);