[PATCH 2/2] x86/MCE: Add command line option to extend MCE Records pool

Avadhut Naik
2024-02-07T22:57:03Z

Extension of MCE Records pool, based on system's CPU count, was undertaken
through the previous patch (x86/MCE: Extend size of the MCE Records pool).

Add a new command line parameter "mce-genpool-extend" to set the size of
MCE Records pool to a predetermined number of pages instead of system's
CPU count.

Signed-off-by: Avadhut Naik <avadhut.naik@amd.com>
---
.../admin-guide/kernel-parameters.txt | 2 ++
arch/x86/kernel/cpu/mce/genpool.c | 22 ++++++++++++++++---
2 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 3a1fa1f81d9d..62e7da4d9fda 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3135,6 +3135,8 @@

mce=option [X86-64] See Documentation/arch/x86/x86_64/boot-options.rst

+ mce-genpool-extend= [X86-64] Number of pages to add to MCE Records pool.
+
md= [HW] RAID subsystems devices and level
See Documentation/admin-guide/md.rst.

diff --git a/arch/x86/kernel/cpu/mce/genpool.c b/arch/x86/kernel/cpu/mce/genpool.c
index aed01612d342..d6e04fa5ee07 100644
--- a/arch/x86/kernel/cpu/mce/genpool.c
+++ b/arch/x86/kernel/cpu/mce/genpool.c
@@ -22,6 +22,7 @@
#define MCE_POOLSZ (2 * PAGE_SIZE)
#define CPU_GEN_MEMSZ 256

+static unsigned int mce_genpool_extend;
static struct gen_pool *mce_evt_pool;
static LLIST_HEAD(mce_event_llist);
static char gen_pool_buf[MCE_POOLSZ];
@@ -123,10 +124,14 @@ int mce_gen_pool_extend(void)
int ret = -ENOMEM;
u32 num_threads;

- num_threads = num_present_cpus();
- len = PAGE_ALIGN(num_threads * CPU_GEN_MEMSZ);
- addr = (unsigned long)kzalloc(len, GFP_KERNEL);
+ if (mce_genpool_extend) {
+ len = mce_genpool_extend * PAGE_SIZE;
+ } else {
+ num_threads = num_present_cpus();
+ len = PAGE_ALIGN(num_threads * CPU_GEN_MEMSZ);
+ }

+ addr = (unsigned long)kzalloc(len, GFP_KERNEL);
if (!addr)
goto out;

@@ -159,6 +164,17 @@ static int mce_gen_pool_create(void)
return ret;
}

+static int __init parse_mce_genpool_extend(char *str)
+{
+ if (*str == '=')
+ str++;
+
+ get_option(&str, &mce_genpool_extend);
+ return 1;
+}
+
+__setup("mce-genpool-extend", parse_mce_genpool_extend);
+
int mce_gen_pool_init(void)
{
/* Just init mce_gen_pool once. */
--
2.34.1