On Fri, Dec 29, 2017 at 02:09:40PM +0100, Thomas Gleixner wrote:
> On Fri, 29 Dec 2017, 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.
>
> Nice detective work. Unfortunately that's not a real solution ...
>
Oh, of course. It was never intended as a solution, only as
information perhaps enabling someone who knows what they're doing
(unlike myself :) ) to find one.
> Can you try the patch below on top of Linus tree, please?
>
> Thanks,
>
Applied it to 464e1d5 4.15-rc5 just now. it appears to be
trouble-free: booted, logged me in fine, the works.
> tglx
>
> 8<---------------------
> --- a/kernel/irq/msi.c
> +++ b/kernel/irq/msi.c
> @@ -339,6 +339,40 @@ int msi_domain_populate_irqs(struct irq_
> return ret;
> }
>
> +/*
> + * Carefully check whether the device can use reservation mode. If
> + * reservation mode is enabled then the early activation will assign a
> + * dummy vector to the device. If the PCI/MSI device does not support
> + * masking of the entry then this can result in spurious interrupts when
> + * the device driver is not absolutely careful. But even then a malfunction
> + * of the hardware could result in a spurious interrupt on the dummy vector
> + * and render the device unusable. If the entry can be masked then the core
> + * logic will prevent the spurious interrupt and reservation mode can be
> + * used. For now reservation mode is restricted to PCI/MSI.
> + */
> +static bool msi_check_reservation_mode(struct irq_domain *domain,
> + struct msi_domain_info *info,
> + struct device *dev)
> +{
> + struct msi_desc *desc;
> +
> + if (domain->bus_token != DOMAIN_BUS_PCI_MSI)
> + return false;
> +
> + if (!(info->flags & MSI_FLAG_MUST_REACTIVATE))
> + return false;
> +
> + if (IS_ENABLED(CONFIG_PCI_MSI) && pci_msi_ignore_mask)
> + return false;
> +
> + /*
> + * Checking the first MSI descriptor is sufficient. MSIX supports
> + * masking and MSI does so when the maskbit is set.
> + */
> + desc = first_msi_entry(dev);
> + return desc->msi_attrib.is_msix || desc->msi_attrib.maskbit;
> +}
> +
> /**
> * msi_domain_alloc_irqs - Allocate interrupts from a MSI interrupt domain
> * @domain: The domain to allocate from
> @@ -353,9 +387,11 @@ int msi_domain_alloc_irqs(struct irq_dom
> {
> struct msi_domain_info *info = domain->host_data;
> struct msi_domain_ops *ops = info->ops;
> - msi_alloc_info_t arg;
> + struct irq_data *irq_data;
> struct msi_desc *desc;
> + msi_alloc_info_t arg;
> int i, ret, virq;
> + bool can_reserve;
>
> ret = msi_domain_prepare_irqs(domain, dev, nvec, &arg);
> if (ret)
> @@ -385,6 +421,8 @@ int msi_domain_alloc_irqs(struct irq_dom
> if (ops->msi_finish)
> ops->msi_finish(&arg, 0);
>
> + can_reserve = msi_check_reservation_mode(domain, info, dev);
> +
> for_each_msi_entry(desc, dev) {
> virq = desc->irq;
> if (desc->nvec_used == 1)
> @@ -397,17 +435,28 @@ int msi_domain_alloc_irqs(struct irq_dom
> * the MSI entries before the PCI layer enables MSI in the
> * card. Otherwise the card latches a random msi message.
> */
> - if (info->flags & MSI_FLAG_ACTIVATE_EARLY) {
> - struct irq_data *irq_data;
> + if (!(info->flags & MSI_FLAG_ACTIVATE_EARLY))
> + continue;
>
> + irq_data = irq_domain_get_irq_data(domain, desc->irq);
> + if (!can_reserve)
> + irqd_clr_can_reserve(irq_data);
> + ret = irq_domain_activate_irq(irq_data, can_reserve);
> + if (ret)
> + goto cleanup;
> + }
> +
> + /*
> + * If these interrupts use reservation mode clear the activated bit
> + * so request_irq() will assign the final vector.
> + */
> + if (can_reserve) {
> + for_each_msi_entry(desc, dev) {
> irq_data = irq_domain_get_irq_data(domain, desc->irq);
> - ret = irq_domain_activate_irq(irq_data, true);
> - if (ret)
> - goto cleanup;
> - if (info->flags & MSI_FLAG_MUST_REACTIVATE)
> - irqd_clr_activated(irq_data);
> + irqd_clr_activated(irq_data);
> }
> }
> +
> return 0;
>
> cleanup:
> --- a/arch/x86/kernel/apic/vector.c
> +++ b/arch/x86/kernel/apic/vector.c
> @@ -184,6 +184,7 @@ static void reserve_irq_vector_locked(st
> irq_matrix_reserve(vector_matrix);
> apicd->can_reserve = true;
> apicd->has_reserved = true;
> + irqd_set_can_reserve(irqd);
> trace_vector_reserve(irqd->irq, 0);
> vector_assign_managed_shutdown(irqd);
> }
> @@ -368,8 +369,18 @@ static int activate_reserved(struct irq_
> int ret;
>
> ret = assign_irq_vector_any_locked(irqd);
> - if (!ret)
> + if (!ret) {
> apicd->has_reserved = false;
> + /*
> + * Core might have disabled reservation mode after
> + * allocating the irq descriptor. Ideally this should
> + * happen before allocation time, but that would require
> + * completely convoluted ways of transporting that
> + * information.
> + */
> + if (!irqd_can_reserve(irqd))
> + apicd->can_reserve = false;
> + }
> return ret;
> }
>
> @@ -478,6 +489,7 @@ static bool vector_configure_legacy(unsi
> } else {
> /* Release the vector */
> apicd->can_reserve = true;
> + irqd_set_can_reserve(irqd);
> clear_irq_vector(irqd);
> realloc = true;
> }
> --- a/include/linux/irq.h
> +++ b/include/linux/irq.h
> @@ -212,6 +212,7 @@ struct irq_data {
> * mask. Applies only to affinity managed irqs.
> * IRQD_SINGLE_TARGET - IRQ allows only a single affinity target
> * IRQD_DEFAULT_TRIGGER_SET - Expected trigger already been set
> + * IRQD_CAN_RESERVE - Can use reservation mode
> */
> enum {
> IRQD_TRIGGER_MASK = 0xf,
> @@ -233,6 +234,7 @@ enum {
> IRQD_MANAGED_SHUTDOWN = (1 << 23),
> IRQD_SINGLE_TARGET = (1 << 24),
> IRQD_DEFAULT_TRIGGER_SET = (1 << 25),
> + IRQD_CAN_RESERVE = (1 << 26),
> };
>
> #define __irqd_to_state(d) ACCESS_PRIVATE((d)->common, state_use_accessors)
> @@ -377,6 +379,21 @@ static inline bool irqd_is_managed_and_s
> return __irqd_to_state(d) & IRQD_MANAGED_SHUTDOWN;
> }
>
> +static inline void irqd_set_can_reserve(struct irq_data *d)
> +{
> + __irqd_to_state(d) |= IRQD_CAN_RESERVE;
> +}
> +
> +static inline void irqd_clr_can_reserve(struct irq_data *d)
> +{
> + __irqd_to_state(d) &= ~IRQD_CAN_RESERVE;
> +}
> +
> +static inline bool irqd_can_reserve(struct irq_data *d)
> +{
> + return __irqd_to_state(d) & IRQD_CAN_RESERVE;
> +}
> +
> #undef __irqd_to_state
>
> static inline irq_hw_number_t irqd_to_hwirq(struct irq_data *d)
> --- a/kernel/irq/debugfs.c
> +++ b/kernel/irq/debugfs.c
> @@ -113,6 +113,7 @@ static const struct irq_bit_descr irqdat
> BIT_MASK_DESCR(IRQD_SETAFFINITY_PENDING),
> BIT_MASK_DESCR(IRQD_AFFINITY_MANAGED),
> BIT_MASK_DESCR(IRQD_MANAGED_SHUTDOWN),
> + BIT_MASK_DESCR(IRQD_CAN_RESERVE),
>
> BIT_MASK_DESCR(IRQD_FORWARDED_TO_VCPU),
>
> --- a/arch/x86/kernel/apic/apic_flat_64.c
> +++ b/arch/x86/kernel/apic/apic_flat_64.c
> @@ -151,7 +151,7 @@ static struct apic apic_flat __ro_after_
> .apic_id_valid = default_apic_id_valid,
> .apic_id_registered = flat_apic_id_registered,
>
> - .irq_delivery_mode = dest_LowestPrio,
> + .irq_delivery_mode = dest_Fixed,
> .irq_dest_mode = 1, /* logical */
>
> .disable_esr = 0,
> --- a/arch/x86/kernel/apic/apic_noop.c
> +++ b/arch/x86/kernel/apic/apic_noop.c
> @@ -110,7 +110,7 @@ struct apic apic_noop __ro_after_init =
> .apic_id_valid = default_apic_id_valid,
> .apic_id_registered = noop_apic_id_registered,
>
> - .irq_delivery_mode = dest_LowestPrio,
> + .irq_delivery_mode = dest_Fixed,
> /* logical delivery broadcast to all CPUs: */
> .irq_dest_mode = 1,
>
> --- a/arch/x86/kernel/apic/msi.c
> +++ b/arch/x86/kernel/apic/msi.c
> @@ -39,17 +39,13 @@ static void irq_msi_compose_msg(struct i
> ((apic->irq_dest_mode == 0) ?
> MSI_ADDR_DEST_MODE_PHYSICAL :
> MSI_ADDR_DEST_MODE_LOGICAL) |
> - ((apic->irq_delivery_mode != dest_LowestPrio) ?
> - MSI_ADDR_REDIRECTION_CPU :
> - MSI_ADDR_REDIRECTION_LOWPRI) |
> + MSI_ADDR_REDIRECTION_CPU |
> MSI_ADDR_DEST_ID(cfg->dest_apicid);
>
> msg->data =
> MSI_DATA_TRIGGER_EDGE |
> MSI_DATA_LEVEL_ASSERT |
> - ((apic->irq_delivery_mode != dest_LowestPrio) ?
> - MSI_DATA_DELIVERY_FIXED :
> - MSI_DATA_DELIVERY_LOWPRI) |
> + MSI_DATA_DELIVERY_FIXED |
> MSI_DATA_VECTOR(cfg->vector);
> }
>
> --- a/arch/x86/kernel/apic/probe_32.c
> +++ b/arch/x86/kernel/apic/probe_32.c
> @@ -105,7 +105,7 @@ static struct apic apic_default __ro_aft
> .apic_id_valid = default_apic_id_valid,
> .apic_id_registered = default_apic_id_registered,
>
> - .irq_delivery_mode = dest_LowestPrio,
> + .irq_delivery_mode = dest_Fixed,
> /* logical delivery broadcast to all CPUs: */
> .irq_dest_mode = 1,
>
> --- a/arch/x86/kernel/apic/x2apic_cluster.c
> +++ b/arch/x86/kernel/apic/x2apic_cluster.c
> @@ -184,7 +184,7 @@ static struct apic apic_x2apic_cluster _
> .apic_id_valid = x2apic_apic_id_valid,
> .apic_id_registered = x2apic_apic_id_registered,
>
> - .irq_delivery_mode = dest_LowestPrio,
> + .irq_delivery_mode = dest_Fixed,
> .irq_dest_mode = 1, /* logical */
>
> .disable_esr = 0,
> --- a/drivers/pci/host/pci-hyperv.c
> +++ b/drivers/pci/host/pci-hyperv.c
> @@ -985,9 +985,7 @@ static u32 hv_compose_msi_req_v1(
> int_pkt->wslot.slot = slot;
> int_pkt->int_desc.vector = vector;
> int_pkt->int_desc.vector_count = 1;
> - int_pkt->int_desc.delivery_mode =
> - (apic->irq_delivery_mode == dest_LowestPrio) ?
> - dest_LowestPrio : dest_Fixed;
> + int_pkt->int_desc.delivery_mode = dest_Fixed;
>
> /*
> * Create MSI w/ dummy vCPU set, overwritten by subsequent retarget in
> @@ -1008,9 +1006,7 @@ static u32 hv_compose_msi_req_v2(
> int_pkt->wslot.slot = slot;
> int_pkt->int_desc.vector = vector;
> int_pkt->int_desc.vector_count = 1;
> - int_pkt->int_desc.delivery_mode =
> - (apic->irq_delivery_mode == dest_LowestPrio) ?
> - dest_LowestPrio : dest_Fixed;
> + int_pkt->int_desc.delivery_mode = dest_Fixed;
>
> /*
> * Create MSI w/ dummy vCPU set targeting just one vCPU, overwritten
