[tip: ras/core] x86/mce: Stop mce_reign() from re-computing severity for every CPU

tip-bot2 for Tony Luck
2020-09-14T17:32:59Z

The following commit has been merged into the ras/core branch of tip:

Commit-ID: 13c877f4b48b943105ad9e13ba2c7a093fb694e8
Gitweb: https://git.kernel.org/tip/13c877f4b48b943105ad9e13ba2c7a093fb694e8
Author: Tony Luck <tony.luck@intel.com>
AuthorDate: Tue, 08 Sep 2020 10:55:12 -07:00
Committer: Borislav Petkov <bp@suse.de>
CommitterDate: Mon, 14 Sep 2020 19:25:23 +02:00

x86/mce: Stop mce_reign() from re-computing severity for every CPU

Back in commit:

20d51a426fe9 ("x86/mce: Reuse one of the u16 padding fields in 'struct mce'")

a field was added to "struct mce" to save the computed error severity.

Make use of this in mce_reign() to avoid re-computing the severity
for every CPU.

In the case where the machine panics, one call to mce_severity() is
still needed in order to provide the correct message giving the reason
for the panic.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200908175519.14223-2-tony.luck@intel.com
---
arch/x86/kernel/cpu/mce/core.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index a697bae..5b1d5f3 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -920,7 +920,6 @@ static void mce_reign(void)
struct mce *m = NULL;
int global_worst = 0;
char *msg = NULL;
- char *nmsg = NULL;

/*
* This CPU is the Monarch and the other CPUs have run
@@ -928,12 +927,10 @@ static void mce_reign(void)
* Grade the severity of the errors of all the CPUs.
*/
for_each_possible_cpu(cpu) {
- int severity = mce_severity(&per_cpu(mces_seen, cpu),
- mca_cfg.tolerant,
- &nmsg, true);
- if (severity > global_worst) {
- msg = nmsg;
- global_worst = severity;
+ struct mce *mtmp = &per_cpu(mces_seen, cpu);
+
+ if (mtmp->severity > global_worst) {
+ global_worst = mtmp->severity;
m = &per_cpu(mces_seen, cpu);
}
}
@@ -943,8 +940,11 @@ static void mce_reign(void)
* This dumps all the mces in the log buffer and stops the
* other CPUs.
*/
- if (m && global_worst >= MCE_PANIC_SEVERITY && mca_cfg.tolerant < 3)
+ if (m && global_worst >= MCE_PANIC_SEVERITY && mca_cfg.tolerant < 3) {
+ /* call mce_severity() to get "msg" for panic */
+ mce_severity(m, mca_cfg.tolerant, &msg, true);
mce_panic("Fatal machine check", m, msg);
+ }

/*
* For UC somewhere we let the CPU who detects it handle it.