From 108c6494bdf1dfeaefc0a506e2f471aa92fafdd6 Mon Sep 17 00:00:00 2001 From: Tony Luck Date: Thu, 7 Mar 2024 11:27:04 -0800 Subject: x86/mce: Dynamically size space for machine check records Systems with a large number of CPUs may generate a large number of machine check records when things go seriously wrong. But Linux has a fixed-size buffer that can only capture a few dozen errors. Allocate space based on the number of CPUs (with a minimum value based on the historical fixed buffer that could store 80 records). [ bp: Rename local var from tmpp to something more telling: gpool. ] Signed-off-by: Tony Luck Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Sohil Mehta Reviewed-by: Avadhut Naik Link: https://lore.kernel.org/r/20240307192704.37213-1-tony.luck@intel.com --- arch/x86/kernel/cpu/mce/genpool.c | 40 ++++++++++++++++++++++++--------------- 1 file changed, 25 insertions(+), 15 deletions(-) (limited to 'arch') diff --git a/arch/x86/kernel/cpu/mce/genpool.c b/arch/x86/kernel/cpu/mce/genpool.c index fbe8b61c3413..4284749ec803 100644 --- a/arch/x86/kernel/cpu/mce/genpool.c +++ b/arch/x86/kernel/cpu/mce/genpool.c @@ -16,14 +16,14 @@ * used to save error information organized in a lock-less list. * * This memory pool is only to be used to save MCE records in MCE context. - * MCE events are rare, so a fixed size memory pool should be enough. Use - * 2 pages to save MCE events for now (~80 MCE records at most). + * MCE events are rare, so a fixed size memory pool should be enough. + * Allocate on a sliding scale based on number of CPUs. */ -#define MCE_POOLSZ (2 * PAGE_SIZE) +#define MCE_MIN_ENTRIES 80 +#define MCE_PER_CPU 2 static struct gen_pool *mce_evt_pool; static LLIST_HEAD(mce_event_llist); -static char gen_pool_buf[MCE_POOLSZ]; /* * Compare the record "t" with each of the records on list "l" to see if @@ -118,22 +118,32 @@ int mce_gen_pool_add(struct mce *mce) static int mce_gen_pool_create(void) { - struct gen_pool *tmpp; + int mce_numrecords, mce_poolsz, order; + struct gen_pool *gpool; int ret = -ENOMEM; - - tmpp = gen_pool_create(ilog2(sizeof(struct mce_evt_llist)), -1); - if (!tmpp) - goto out; - - ret = gen_pool_add(tmpp, (unsigned long)gen_pool_buf, MCE_POOLSZ, -1); + void *mce_pool; + + order = order_base_2(sizeof(struct mce_evt_llist)); + gpool = gen_pool_create(order, -1); + if (!gpool) + return ret; + + mce_numrecords = max(MCE_MIN_ENTRIES, num_possible_cpus() * MCE_PER_CPU); + mce_poolsz = mce_numrecords * (1 << order); + mce_pool = kmalloc(mce_poolsz, GFP_KERNEL); + if (!mce_pool) { + gen_pool_destroy(gpool); + return ret; + } + ret = gen_pool_add(gpool, (unsigned long)mce_pool, mce_poolsz, -1); if (ret) { - gen_pool_destroy(tmpp); - goto out; + gen_pool_destroy(gpool); + kfree(mce_pool); + return ret; } - mce_evt_pool = tmpp; + mce_evt_pool = gpool; -out: return ret; } -- cgit v1.2.3