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SubjectRe: IRQ behaivour has been changed from v4.14 to v4.15-rc1
On Fri, 29 Dec 2017, Andy Shevchenko wrote:

> On Thu, 2017-12-28 at 22:59 +0100, Thomas Gleixner wrote:
> > On Thu, 28 Dec 2017, Thomas Gleixner wrote:
> > > On Thu, 28 Dec 2017, Andy Shevchenko wrote:
>
> > > > The result w/o above is (full log is available here
> > > > https://pastebin.com
> > > > /J5yaTbM9):
> > >
> > > Ok. Which irqs are related to that ISP thingy?
> > >
> > > Are these interrupts MSI?
>
> Yes, they are MSI.
>
> > And looking at the log, I see that you can load the driver
> > successfully and
> > the trouble starts afterwards when you actually use it.
>
> Correct.
>
> > Can you please enable CONFIG_GENERIC_IRQ_DEBUGFS and after login,
> > check
> > which interrupt is assigned to that atomisp thingy and then provide
> > the
> > output of
> >
> > cat /sys/kernel/debug/irq/irqs/$ATOMISPIRQ
>
> Full log, including output of the above.
>
> https://pastebin.com/4jammqi5

Thanks for the info. Can you please test the patch below?

Thanks,

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
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