[PATCH v2] powerpc/pseries: Enable hardlockup watchdog for PowerVM partitions
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STALE1939d
LANDED
From: Nicholas Piggin <npiggin@gmail.com>
Date: 2021-06-23 02:16:12
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Linus Torvalds
Landed in mainline as 633c8e9800f3 on 2021-06-24.
PowerVM will not arbitrarily oversubscribe or stop guests, page out the guest kernel text to a NFS volume connected by carrier pigeon to abacus based storage, etc., as a KVM host might. So PowerVM guests are not likely to be killed by the hard lockup watchdog in normal operation, even with shared processor LPARs which still get a minimum allotment of CPU time. Enable the hard lockup detector by default on !KVM guests, which we will assume is PowerVM. It has been useful in finding problems on bare metal kernels. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> --- v2: Fix 64e build by including kvm_guest.h arch/powerpc/kernel/setup_64.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index e42b85e4f1aa..428058dc5114 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c@@ -33,6 +33,7 @@ #include <linux/pgtable.h> #include <asm/debugfs.h> +#include <asm/kvm_guest.h> #include <asm/io.h> #include <asm/kdump.h> #include <asm/prom.h>
@@ -939,16 +940,20 @@ u64 hw_nmi_get_sample_period(int watchdog_thresh) * disable it by default. Book3S has a soft-nmi hardlockup detector based * on the decrementer interrupt, so it does not suffer from this problem. * - * It is likely to get false positives in VM guests, so disable it there - * by default too. + * It is likely to get false positives in KVM guests, so disable it there + * by default too. PowerVM will not stop or arbitrarily oversubscribe + * CPUs, but give a minimum regular allotment even with SPLPAR, so enable + * the detector for non-KVM guests, assume PowerVM. */ static int __init disable_hardlockup_detector(void) { #ifdef CONFIG_HARDLOCKUP_DETECTOR_PERF hardlockup_detector_disable(); #else - if (firmware_has_feature(FW_FEATURE_LPAR)) - hardlockup_detector_disable(); + if (firmware_has_feature(FW_FEATURE_LPAR)) { + if (is_kvm_guest()) + hardlockup_detector_disable(); + } #endif return 0;
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2.23.0