| Message ID | 20201107011119.631442-1-bmasney@redhat.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | bdaac6fb4897e0113ae16ab8f09f7cf21812d91f |
| Headers | show |
| Series | [v2] x86/xen: don't unbind uninitialized lock_kicker_irq | expand |
On 07.11.20 02:11, Brian Masney wrote: > When booting a hyperthreaded system with the kernel parameter > 'mitigations=auto,nosmt', the following warning occurs: > > WARNING: CPU: 0 PID: 1 at drivers/xen/events/events_base.c:1112 unbind_from_irqhandler+0x4e/0x60 > ... > Hardware name: Xen HVM domU, BIOS 4.2.amazon 08/24/2006 > ... > Call Trace: > xen_uninit_lock_cpu+0x28/0x62 > xen_hvm_cpu_die+0x21/0x30 > takedown_cpu+0x9c/0xe0 > ? trace_suspend_resume+0x60/0x60 > cpuhp_invoke_callback+0x9a/0x530 > _cpu_up+0x11a/0x130 > cpu_up+0x7e/0xc0 > bringup_nonboot_cpus+0x48/0x50 > smp_init+0x26/0x79 > kernel_init_freeable+0xea/0x229 > ? rest_init+0xaa/0xaa > kernel_init+0xa/0x106 > ret_from_fork+0x35/0x40 > > The secondary CPUs are not activated with the nosmt mitigations and only > the primary thread on each CPU core is used. In this situation, > xen_hvm_smp_prepare_cpus(), and more importantly xen_init_lock_cpu(), is > not called, so the lock_kicker_irq is not initialized for the secondary > CPUs. Let's fix this by exiting early in xen_uninit_lock_cpu() if the > irq is not set to avoid the warning from above for each secondary CPU. > > Signed-off-by: Brian Masney <bmasney@redhat.com> Reviewed-by: Juergen Gross <jgross@suse.com> Juergen
On 11/9/20 12:34 AM, Jürgen Groß wrote: > On 07.11.20 02:11, Brian Masney wrote: >> When booting a hyperthreaded system with the kernel parameter >> 'mitigations=auto,nosmt', the following warning occurs: >> >> WARNING: CPU: 0 PID: 1 at drivers/xen/events/events_base.c:1112 unbind_from_irqhandler+0x4e/0x60 >> ... >> Hardware name: Xen HVM domU, BIOS 4.2.amazon 08/24/2006 >> ... >> Call Trace: >> xen_uninit_lock_cpu+0x28/0x62 >> xen_hvm_cpu_die+0x21/0x30 >> takedown_cpu+0x9c/0xe0 >> ? trace_suspend_resume+0x60/0x60 >> cpuhp_invoke_callback+0x9a/0x530 >> _cpu_up+0x11a/0x130 >> cpu_up+0x7e/0xc0 >> bringup_nonboot_cpus+0x48/0x50 >> smp_init+0x26/0x79 >> kernel_init_freeable+0xea/0x229 >> ? rest_init+0xaa/0xaa >> kernel_init+0xa/0x106 >> ret_from_fork+0x35/0x40 >> >> The secondary CPUs are not activated with the nosmt mitigations and only >> the primary thread on each CPU core is used. In this situation, >> xen_hvm_smp_prepare_cpus(), and more importantly xen_init_lock_cpu(), is >> not called, so the lock_kicker_irq is not initialized for the secondary >> CPUs. Let's fix this by exiting early in xen_uninit_lock_cpu() if the >> irq is not set to avoid the warning from above for each secondary CPU. >> >> Signed-off-by: Brian Masney <bmasney@redhat.com> > > Reviewed-by: Juergen Gross <jgross@suse.com> Applied to for-linus-5.10b. -boris
diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c index 799f4eba0a62..043c73dfd2c9 100644 --- a/arch/x86/xen/spinlock.c +++ b/arch/x86/xen/spinlock.c @@ -93,10 +93,20 @@ void xen_init_lock_cpu(int cpu) void xen_uninit_lock_cpu(int cpu) { + int irq; + if (!xen_pvspin) return; - unbind_from_irqhandler(per_cpu(lock_kicker_irq, cpu), NULL); + /* + * When booting the kernel with 'mitigations=auto,nosmt', the secondary + * CPUs are not activated, and lock_kicker_irq is not initialized. + */ + irq = per_cpu(lock_kicker_irq, cpu); + if (irq == -1) + return; + + unbind_from_irqhandler(irq, NULL); per_cpu(lock_kicker_irq, cpu) = -1; kfree(per_cpu(irq_name, cpu)); per_cpu(irq_name, cpu) = NULL;
When booting a hyperthreaded system with the kernel parameter 'mitigations=auto,nosmt', the following warning occurs: WARNING: CPU: 0 PID: 1 at drivers/xen/events/events_base.c:1112 unbind_from_irqhandler+0x4e/0x60 ... Hardware name: Xen HVM domU, BIOS 4.2.amazon 08/24/2006 ... Call Trace: xen_uninit_lock_cpu+0x28/0x62 xen_hvm_cpu_die+0x21/0x30 takedown_cpu+0x9c/0xe0 ? trace_suspend_resume+0x60/0x60 cpuhp_invoke_callback+0x9a/0x530 _cpu_up+0x11a/0x130 cpu_up+0x7e/0xc0 bringup_nonboot_cpus+0x48/0x50 smp_init+0x26/0x79 kernel_init_freeable+0xea/0x229 ? rest_init+0xaa/0xaa kernel_init+0xa/0x106 ret_from_fork+0x35/0x40 The secondary CPUs are not activated with the nosmt mitigations and only the primary thread on each CPU core is used. In this situation, xen_hvm_smp_prepare_cpus(), and more importantly xen_init_lock_cpu(), is not called, so the lock_kicker_irq is not initialized for the secondary CPUs. Let's fix this by exiting early in xen_uninit_lock_cpu() if the irq is not set to avoid the warning from above for each secondary CPU. Signed-off-by: Brian Masney <bmasney@redhat.com> --- Changes since v1: - Remove duplicate per_cpu() call and pass in irq variable. - Changed subject from 'x86/xen: fix warning when running with nosmt mitigations' - Shorten code comment arch/x86/xen/spinlock.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-)