[patch V2 26/31] genirq/msi: Make interrupt allocation less convoluted

Thomas Gleixner
2021-12-06T22:53:12Z

There is no real reason to do several loops over the MSI descriptors
instead of just doing one loop. In case of an error everything is undone
anyway so it does not matter whether it's a partial or a full rollback.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
.clang-format | 1
include/linux/msi.h | 6 --
kernel/irq/msi.c | 129 +++++++++++++++++++++++++++-------------------------
3 files changed, 69 insertions(+), 67 deletions(-)

--- a/.clang-format
+++ b/.clang-format
@@ -216,7 +216,6 @@ ExperimentalAutoDetectBinPacking: false
- 'for_each_migratetype_order'
- 'for_each_msi_entry'
- 'for_each_msi_entry_safe'
- - 'for_each_msi_vector'
- 'for_each_net'
- 'for_each_net_continue_reverse'
- 'for_each_netdev'
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -223,12 +223,6 @@ struct msi_desc *msi_next_desc(struct de
list_for_each_entry((desc), dev_to_msi_list((dev)), list)
#define for_each_msi_entry_safe(desc, tmp, dev) \
list_for_each_entry_safe((desc), (tmp), dev_to_msi_list((dev)), list)
-#define for_each_msi_vector(desc, __irq, dev) \
- for_each_msi_entry((desc), (dev)) \
- if ((desc)->irq) \
- for (__irq = (desc)->irq; \
- __irq < ((desc)->irq + (desc)->nvec_used); \
- __irq++)

#ifdef CONFIG_IRQ_MSI_IOMMU
static inline const void *msi_desc_get_iommu_cookie(struct msi_desc *desc)
--- a/kernel/irq/msi.c
+++ b/kernel/irq/msi.c
@@ -856,23 +856,74 @@ static int msi_handle_pci_fail(struct ir
return allocated ? allocated : -ENOSPC;
}

+#define VIRQ_CAN_RESERVE 0x01
+#define VIRQ_ACTIVATE 0x02
+#define VIRQ_NOMASK_QUIRK 0x04
+
+static int msi_init_virq(struct irq_domain *domain, int virq, unsigned int vflags)
+{
+ struct irq_data *irqd = irq_domain_get_irq_data(domain, virq);
+ int ret;
+
+ if (!(vflags & VIRQ_CAN_RESERVE)) {
+ irqd_clr_can_reserve(irqd);
+ if (vflags & VIRQ_NOMASK_QUIRK)
+ irqd_set_msi_nomask_quirk(irqd);
+ }
+
+ if (!(vflags & VIRQ_ACTIVATE))
+ return 0;
+
+ ret = irq_domain_activate_irq(irqd, vflags & VIRQ_CAN_RESERVE);
+ if (ret)
+ return ret;
+ /*
+ * If the interrupt uses reservation mode, clear the activated bit
+ * so request_irq() will assign the final vector.
+ */
+ if (vflags & VIRQ_CAN_RESERVE)
+ irqd_clr_activated(irqd);
+ return 0;
+}
+
int __msi_domain_alloc_irqs(struct irq_domain *domain, struct device *dev,
int nvec)
{
struct msi_domain_info *info = domain->host_data;
struct msi_domain_ops *ops = info->ops;
- struct irq_data *irq_data;
- struct msi_desc *desc;
msi_alloc_info_t arg = { };
+ unsigned int vflags = 0;
+ struct msi_desc *desc;
int allocated = 0;
int i, ret, virq;
- bool can_reserve;

ret = msi_domain_prepare_irqs(domain, dev, nvec, &arg);
if (ret)
return ret;

- for_each_msi_entry(desc, dev) {
+ /*
+ * This flag is set by the PCI layer as we need to activate
+ * 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)
+ vflags |= VIRQ_ACTIVATE;
+
+ /*
+ * Interrupt can use a reserved vector and will not occupy
+ * a real device vector until the interrupt is requested.
+ */
+ if (msi_check_reservation_mode(domain, info, dev)) {
+ vflags |= VIRQ_CAN_RESERVE;
+ /*
+ * MSI affinity setting requires a special quirk (X86) when
+ * reservation mode is active.
+ */
+ if (domain->flags & IRQ_DOMAIN_MSI_NOMASK_QUIRK)
+ vflags |= VIRQ_NOMASK_QUIRK;
+ }
+
+ msi_for_each_desc(desc, dev, MSI_DESC_NOTASSOCIATED) {
ops->set_desc(&arg, desc);

virq = __irq_domain_alloc_irqs(domain, -1, desc->nvec_used,
@@ -884,49 +935,12 @@ int __msi_domain_alloc_irqs(struct irq_d
for (i = 0; i < desc->nvec_used; i++) {
irq_set_msi_desc_off(virq, i, desc);
irq_debugfs_copy_devname(virq + i, dev);
+ ret = msi_init_virq(domain, virq + i, vflags);
+ if (ret)
+ return ret;
}
allocated++;
}
-
- can_reserve = msi_check_reservation_mode(domain, info, dev);
-
- /*
- * This flag is set by the PCI layer as we need to activate
- * 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))
- goto skip_activate;
-
- for_each_msi_vector(desc, i, dev) {
- if (desc->irq == i) {
- virq = desc->irq;
- dev_dbg(dev, "irq [%d-%d] for MSI\n",
- virq, virq + desc->nvec_used - 1);
- }
-
- irq_data = irq_domain_get_irq_data(domain, i);
- if (!can_reserve) {
- irqd_clr_can_reserve(irq_data);
- if (domain->flags & IRQ_DOMAIN_MSI_NOMASK_QUIRK)
- irqd_set_msi_nomask_quirk(irq_data);
- }
- ret = irq_domain_activate_irq(irq_data, can_reserve);
- if (ret)
- return ret;
- }
-
-skip_activate:
- /*
- * If these interrupts use reservation mode, clear the activated bit
- * so request_irq() will assign the final vector.
- */
- if (can_reserve) {
- for_each_msi_vector(desc, i, dev) {
- irq_data = irq_domain_get_irq_data(domain, i);
- irqd_clr_activated(irq_data);
- }
- }
return 0;
}

@@ -1004,26 +1018,21 @@ int msi_domain_alloc_irqs(struct irq_dom

void __msi_domain_free_irqs(struct irq_domain *domain, struct device *dev)
{
- struct irq_data *irq_data;
+ struct irq_data *irqd;
struct msi_desc *desc;
int i;

- for_each_msi_vector(desc, i, dev) {
- irq_data = irq_domain_get_irq_data(domain, i);
- if (irqd_is_activated(irq_data))
- irq_domain_deactivate_irq(irq_data);
- }
-
- for_each_msi_entry(desc, dev) {
- /*
- * We might have failed to allocate an MSI early
- * enough that there is no IRQ associated to this
- * entry. If that's the case, don't do anything.
- */
- if (desc->irq) {
- irq_domain_free_irqs(desc->irq, desc->nvec_used);
- desc->irq = 0;
+ /* Only handle MSI entries which have an interrupt associated */
+ msi_for_each_desc(desc, dev, MSI_DESC_ASSOCIATED) {
+ /* Make sure all interrupts are deactivated */
+ for (i = 0; i < desc->nvec_used; i++) {
+ irqd = irq_domain_get_irq_data(domain, desc->irq + i);
+ if (irqd && irqd_is_activated(irqd))
+ irq_domain_deactivate_irq(irqd);
}
+
+ irq_domain_free_irqs(desc->irq, desc->nvec_used);
+ desc->irq = 0;
}
}