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SubjectRe: PROBLEM: 4.15.0-rc3 APIC causes lockups on Core 2 Duo laptop
On Fri, Dec 29, 2017 at 06:49:15AM -0500, Alexandru Chirvasitu wrote:
> All right, I tried to do some more digging around, in the hope of
> getting as close to the source of the problem as I can.
>
> I went back to the very first commit that went astray for me, 2db1f95
> (which is the only one actually panicking), and tried to move from its
> parent 90ad9e2 (that boots fine) to it gradually, altering the code in
> small chunks.
>
> I tried to ignore the stuff that clearly shouldn't make a difference,
> such as definitions. So in the end I get defined-but-unused-function
> errors in my compilations, but I'm ignoring those for now. Some
> results:
>
> (1) When I move from the good commit 90ad9e2 according to the attached
> bad-diff (which moves partly towards 2db1f95), I get a panic.
>
> (2) On the other hand, when I further change this last panicking
> commit by simply doing
>
>
> ----------------------------------------------------------------
> removed activate / deactivate from x86_vector_domain_ops
>
> diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c
> index 7317ba5a..063594d 100644
> --- a/arch/x86/kernel/apic/vector.c
> +++ b/arch/x86/kernel/apic/vector.c
> @@ -514,8 +514,6 @@ void x86_vector_debug_show(struct seq_file *m, struct irq_domain *d,
> static const struct irq_domain_ops x86_vector_domain_ops = {
> .alloc = x86_vector_alloc_irqs,
> .free = x86_vector_free_irqs,
> - .activate = x86_vector_activate,
> - .deactivate = x86_vector_deactivate,
> #ifdef CONFIG_GENERIC_IRQ_DEBUGFS
> .debug_show = x86_vector_debug_show,
> #endif
> ----------------------------------------------------------------
>
> all is well.
>

And sure enough, simply diffing

----------------------------------------------------------------
removed activate / deactivate from x86_vector_domain_ops

diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c
index 3f53572..e6cb55d 100644
--- a/arch/x86/kernel/apic/vector.c
+++ b/arch/x86/kernel/apic/vector.c
@@ -511,8 +511,6 @@ void x86_vector_debug_show(struct seq_file *m, struct irq_domain *d,
static const struct irq_domain_ops x86_vector_domain_ops = {
.alloc = x86_vector_alloc_irqs,
.free = x86_vector_free_irqs,
- .activate = x86_vector_activate,
- .deactivate = x86_vector_deactivate,
#ifdef CONFIG_GENERIC_IRQ_DEBUGFS
.debug_show = x86_vector_debug_show,
#endif
----------------------------------------------------------------
directly against 2db1f95 fixes the issues (no freezes, lockups, or
panics).




>
>
>
> On Fri, Dec 29, 2017 at 09:07:45AM +0100, Thomas Gleixner wrote:
> > On Thu, 28 Dec 2017, Alexandru Chirvasitu wrote:
> > > On Fri, Dec 29, 2017 at 12:36:37AM +0100, Thomas Gleixner wrote:
> > > > On Thu, 28 Dec 2017, Alexandru Chirvasitu wrote:
> > > >
> > > > > Attached, but heads up on this: when redirecting the output of lspci
> > > > > -vvv to a text file as root I get
> > > > >
> > > > > pcilib: sysfs_read_vpd: read failed: Input/output error
> > > > >
> > > > > I can find bugs filed for various distros to this same effect, but
> > > > > haven't tracked down any explanations.
> > > >
> > > > Weird, but the info looks complete.
> > > >
> > > > Can you please add 'pci=nomsi' to the 4.15 kernel command line and see
> > > > whether that works?
> > >
> > > It does (emailing from that successful boot as we speak). I'm on a
> > > clean 4.15-rc5 (as in no patches, etc.).
> > >
> > > This was also suggested way at the top of this thread by Dexuan Cui
> > > for 4.15-rc3 (where this exchange started), and it worked back then
> > > too.
> >
> > I missed that part of the conversation. Let me stare into the MSI code
> > again.
> >
> > Thanks,
> >
> > tglx

> diff --git a/arch/x86/include/asm/irq_vectors.h b/arch/x86/include/asm/irq_vectors.h
> index aaf8d28..1e9bd28 100644
> --- a/arch/x86/include/asm/irq_vectors.h
> +++ b/arch/x86/include/asm/irq_vectors.h
> @@ -101,12 +101,8 @@
> #define POSTED_INTR_NESTED_VECTOR 0xf0
> #endif
>
> -/*
> - * Local APIC timer IRQ vector is on a different priority level,
> - * to work around the 'lost local interrupt if more than 2 IRQ
> - * sources per level' errata.
> - */
> -#define LOCAL_TIMER_VECTOR 0xef
> +#define MANAGED_IRQ_SHUTDOWN_VECTOR 0xef
> +#define LOCAL_TIMER_VECTOR 0xee
>
> #define NR_VECTORS 256
>
> diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c
> index f08d44f..7317ba5a 100644
> --- a/arch/x86/kernel/apic/vector.c
> +++ b/arch/x86/kernel/apic/vector.c
> @@ -32,7 +32,8 @@ struct apic_chip_data {
> unsigned int prev_cpu;
> unsigned int irq;
> struct hlist_node clist;
> - u8 move_in_progress : 1;
> + unsigned int move_in_progress : 1,
> + is_managed : 1;
> };
>
> struct irq_domain *x86_vector_domain;
> @@ -152,6 +153,28 @@ static void apic_update_vector(struct irq_data *irqd, unsigned int newvec,
> per_cpu(vector_irq, newcpu)[newvec] = desc;
> }
>
> +static void vector_assign_managed_shutdown(struct irq_data *irqd)
> +{
> + unsigned int cpu = cpumask_first(cpu_online_mask);
> +
> + apic_update_irq_cfg(irqd, MANAGED_IRQ_SHUTDOWN_VECTOR, cpu);
> +}
> +
> +static int reserve_managed_vector(struct irq_data *irqd)
> +{
> + const struct cpumask *affmsk = irq_data_get_affinity_mask(irqd);
> + struct apic_chip_data *apicd = apic_chip_data(irqd);
> + unsigned long flags;
> + int ret;
> +
> + raw_spin_lock_irqsave(&vector_lock, flags);
> + apicd->is_managed = true;
> + ret = irq_matrix_reserve_managed(vector_matrix, affmsk);
> + raw_spin_unlock_irqrestore(&vector_lock, flags);
> + trace_vector_reserve_managed(irqd->irq, ret);
> + return ret;
> +}
> +
> static int allocate_vector(struct irq_data *irqd, const struct cpumask *dest)
> {
> struct apic_chip_data *apicd = apic_chip_data(irqd);
> @@ -211,9 +234,58 @@ static int assign_irq_vector_policy(struct irq_data *irqd,
> return assign_irq_vector(irqd, cpu_online_mask);
> }
>
> +
> +static int assign_irq_vector_any_locked(struct irq_data *irqd)
> +{
> + int node = irq_data_get_node(irqd);
> +
> + if (node != NUMA_NO_NODE) {
> + if (!assign_vector_locked(irqd, cpumask_of_node(node)))
> + return 0;
> + }
> + return assign_vector_locked(irqd, cpu_online_mask);
> +}
> +
> +static int assign_irq_vector_any(struct irq_data *irqd)
> +{
> + unsigned long flags;
> + int ret;
> +
> + raw_spin_lock_irqsave(&vector_lock, flags);
> + ret = assign_irq_vector_any_locked(irqd);
> + raw_spin_unlock_irqrestore(&vector_lock, flags);
> + return ret;
> +}
> +
> +
> +static int assign_managed_vector(struct irq_data *irqd, const struct cpumask *dest)
> +{
> + const struct cpumask *affmsk = irq_data_get_affinity_mask(irqd);
> + struct apic_chip_data *apicd = apic_chip_data(irqd);
> + int vector, cpu;
> +
> + cpumask_and(vector_searchmask, vector_searchmask, affmsk);
> + cpu = cpumask_first(vector_searchmask);
> + if (cpu >= nr_cpu_ids)
> + return -EINVAL;
> + /* set_affinity might call here for nothing */
> + if (apicd->vector && cpumask_test_cpu(apicd->cpu, vector_searchmask))
> + return 0;
> + vector = irq_matrix_alloc_managed(vector_matrix, cpu);
> + trace_vector_alloc_managed(irqd->irq, vector, vector);
> + if (vector < 0)
> + return vector;
> + apic_update_vector(irqd, vector, cpu);
> + apic_update_irq_cfg(irqd, vector, cpu);
> + return 0;
> +}
> +
> +
> +
> static void clear_irq_vector(struct irq_data *irqd)
> {
> struct apic_chip_data *apicd = apic_chip_data(irqd);
> + bool managed = irqd_affinity_is_managed(irqd);
> unsigned int vector = apicd->vector;
>
> lockdep_assert_held(&vector_lock);
> @@ -240,6 +312,80 @@ static void clear_irq_vector(struct irq_data *irqd)
> hlist_del_init(&apicd->clist);
> }
>
> +static void x86_vector_deactivate(struct irq_domain *dom, struct irq_data *irqd)
> +{
> + struct apic_chip_data *apicd = apic_chip_data(irqd);
> + unsigned long flags;
> +
> + trace_vector_deactivate(irqd->irq, apicd->is_managed,
> + false, false);
> +
> + if (apicd->is_managed)
> + return;
> +
> + raw_spin_lock_irqsave(&vector_lock, flags);
> + clear_irq_vector(irqd);
> + vector_assign_managed_shutdown(irqd);
> + raw_spin_unlock_irqrestore(&vector_lock, flags);
> +}
> +
> +static int activate_managed(struct irq_data *irqd)
> +{
> + const struct cpumask *dest = irq_data_get_affinity_mask(irqd);
> + int ret;
> +
> + cpumask_and(vector_searchmask, dest, cpu_online_mask);
> + if (WARN_ON_ONCE(cpumask_empty(vector_searchmask))) {
> + /* Something in the core code broke! Survive gracefully */
> + pr_err("Managed startup for irq %u, but no CPU\n", irqd->irq);
> + return EINVAL;
> + }
> +
> + ret = assign_managed_vector(irqd, vector_searchmask);
> + /*
> + * This should not happen. The vector reservation got buggered. Handle
> + * it gracefully.
> + */
> + if (WARN_ON_ONCE(ret < 0)) {
> + pr_err("Managed startup irq %u, no vector available\n",
> + irqd->irq);
> + }
> + return ret;
> +}
> +
> +static int x86_vector_activate(struct irq_domain *dom, struct irq_data *irqd,
> + bool early)
> +{
> + struct apic_chip_data *apicd = apic_chip_data(irqd);
> + unsigned long flags;
> + int ret = 0;
> +
> + trace_vector_activate(irqd->irq, apicd->is_managed,
> + false, early);
> +
> + if (!apicd->is_managed)
> + return 0;
> +
> + raw_spin_lock_irqsave(&vector_lock, flags);
> + if (early || irqd_is_managed_and_shutdown(irqd))
> + vector_assign_managed_shutdown(irqd);
> + else
> + ret = activate_managed(irqd);
> + raw_spin_unlock_irqrestore(&vector_lock, flags);
> + return ret;
> +}
> +
> +static void vector_free_reserved_and_managed(struct irq_data *irqd)
> +{
> + const struct cpumask *dest = irq_data_get_affinity_mask(irqd);
> + struct apic_chip_data *apicd = apic_chip_data(irqd);
> +
> + trace_vector_teardown(irqd->irq, apicd->is_managed, false);
> +
> + if (apicd->is_managed)
> + irq_matrix_remove_managed(vector_matrix, dest);
> +}
> +
> static void x86_vector_free_irqs(struct irq_domain *domain,
> unsigned int virq, unsigned int nr_irqs)
> {
> @@ -368,6 +514,8 @@ void x86_vector_debug_show(struct seq_file *m, struct irq_domain *d,
> static const struct irq_domain_ops x86_vector_domain_ops = {
> .alloc = x86_vector_alloc_irqs,
> .free = x86_vector_free_irqs,
> + .activate = x86_vector_activate,
> + .deactivate = x86_vector_deactivate,
> #ifdef CONFIG_GENERIC_IRQ_DEBUGFS
> .debug_show = x86_vector_debug_show,
> #endif
> @@ -577,6 +725,15 @@ static void free_moved_vector(struct apic_chip_data *apicd)
> {
> unsigned int vector = apicd->prev_vector;
> unsigned int cpu = apicd->prev_cpu;
> + bool managed = apicd->is_managed;
> +
> + /*
> + * This should never happen. Managed interrupts are not
> + * migrated except on CPU down, which does not involve the
> + * cleanup vector. But try to keep the accounting correct
> + * nevertheless.
> + */
> + WARN_ON_ONCE(managed);
>
> trace_vector_free_moved(apicd->irq, vector, false);
> irq_matrix_free(vector_matrix, cpu, vector, false);

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