As per the kernel documentation[1], hardlockup detector should be
disabled in KVM guests as it may give false positives. On PPC, hardlockup
detector is broken inside KVM guests because disable_hardlockup_detector()
is marked as early_initcall and it uses is_kvm_guest(), which is
initialized by check_kvm_guest() later during boot as it is a
core_initcall. check_kvm_guest() is also called in pSeries_smp_probe(),
which is called before initcalls, but it is skipped if KVM guest does
not have doorbell support or if the guest is launched with SMT=1.
Move the check_kvm_guest() call in pSeries_smp_probe() to the initial
part of function before doorbell/SMT checks so that "kvm_guest" static
key is initialized by the time disable_hardlockup_detector() runs.
[1]: Documentation/admin-guide/sysctl/kernel.rst
Signed-off-by: Gautam Menghani <gau...@linux.ibm.com>
---
arch/powerpc/platforms/pseries/smp.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/platforms/pseries/smp.c
b/arch/powerpc/platforms/pseries/smp.c
index c597711ef20a..516c7bfec933 100644
--- a/arch/powerpc/platforms/pseries/smp.c
+++ b/arch/powerpc/platforms/pseries/smp.c
@@ -199,6 +199,13 @@ static __init void pSeries_smp_probe(void)
else
xics_smp_probe();
+ /*
+ * Make sure this is called regardless of doorbell/SMT status, as
+ * we disable hardlockup detector in an early_initcall where we need to
+ * know KVM status for disabling hardlockup detector in KVM guests.
+ */
+ check_kvm_guest();
+
/* No doorbell facility, must use the interrupt controller for IPIs */
if (!cpu_has_feature(CPU_FTR_DBELL))
return;
@@ -207,8 +214,6 @@ static __init void pSeries_smp_probe(void)
if (!cpu_has_feature(CPU_FTR_SMT))
return;
- check_kvm_guest();
-
if (is_kvm_guest()) {
/*
* KVM emulates doorbells by disabling FSCR[MSGP] so msgsndp
--
2.47.0
