[PATCH] x86: microcode: fix return value for microcode late loading

From: Mihai Carabas
Date: Tue Apr 14 2020 - 09:08:44 EST


The return value from stop_machine might not be consistent.

stop_machine_cpuslocked returns:
- zero if all functions have returned 0
- a non-zero value if at least one of the functions returned
a non-zero value

There is no way to know if it is negative or positive. So make
__reload_late return 0 on success, or negative otherwise.

Signed-off-by: Mihai Carabas <mihai.carabas@xxxxxxxxxx>
---
arch/x86/kernel/cpu/microcode/core.c | 11 ++++-------
1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
index 7019d4b..336003e 100644
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -545,8 +545,7 @@ static int __wait_for_cpus(atomic_t *t, long long timeout)
/*
* Returns:
* < 0 - on error
- * 0 - no update done
- * 1 - microcode was updated
+ * 0 - success (no update done or microcode was updated)
*/
static int __reload_late(void *info)
{
@@ -573,11 +572,9 @@ static int __reload_late(void *info)
else
goto wait_for_siblings;

- if (err > UCODE_NFOUND) {
+ if (err >= UCODE_NFOUND) {
pr_warn("Error reloading microcode on CPU %d\n", cpu);
ret = -1;
- } else if (err == UCODE_UPDATED || err == UCODE_OK) {
- ret = 1;
}

wait_for_siblings:
@@ -608,7 +605,7 @@ static int microcode_reload_late(void)
atomic_set(&late_cpus_out, 0);

ret = stop_machine_cpuslocked(__reload_late, NULL, cpu_online_mask);
- if (ret > 0)
+ if (ret == 0)
microcode_check();

pr_info("Reload completed, microcode revision: 0x%x\n", boot_cpu_data.microcode);
@@ -649,7 +646,7 @@ static ssize_t reload_store(struct device *dev,
put:
put_online_cpus();

- if (ret >= 0)
+ if (ret == 0)
ret = size;

return ret;
--
1.8.3.1