[Patch V2 05/13] genirq/msi: Provide and use msi_domain_set_default_info_flags()
From: Megha Dey <hidden>
Date: 2021-02-26 20:23:20
Also in:
linux-iommu, linux-pci, lkml
Subsystem:
irq domains (irq number mapping library), irq subsystem, pci subsystem, the rest · Maintainers:
Thomas Gleixner, Bjorn Helgaas, Linus Torvalds
From: Thomas Gleixner <redacted> MSI interrupts have some common flags which should be set not only for PCI/MSI interrupts. Move the PCI/MSI flag setting into a common function so it can be reused. Reviewed-by: Tony Luck <tony.luck@intel.com> Signed-off-by: Thomas Gleixner <redacted> Signed-off-by: Megha Dey <redacted> --- drivers/pci/msi.c | 7 +------ include/linux/msi.h | 1 + kernel/irq/msi.c | 24 ++++++++++++++++++++++++ 3 files changed, 26 insertions(+), 6 deletions(-)
diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 3162f88..20d2512 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c@@ -1492,12 +1492,7 @@ struct irq_domain *pci_msi_create_irq_domain(struct fwnode_handle *fwnode, if (info->flags & MSI_FLAG_USE_DEF_CHIP_OPS) pci_msi_domain_update_chip_ops(info); - info->flags |= MSI_FLAG_ACTIVATE_EARLY; - if (IS_ENABLED(CONFIG_GENERIC_IRQ_RESERVATION_MODE)) - info->flags |= MSI_FLAG_MUST_REACTIVATE; - - /* PCI-MSI is oneshot-safe */ - info->chip->flags |= IRQCHIP_ONESHOT_SAFE; + msi_domain_set_default_info_flags(info); domain = msi_create_irq_domain(fwnode, info, parent); if (!domain)
diff --git a/include/linux/msi.h b/include/linux/msi.h
index f3e54d2..f6e52de 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h@@ -454,6 +454,7 @@ int platform_msi_domain_alloc(struct irq_domain *domain, unsigned int virq, void platform_msi_domain_free(struct irq_domain *domain, unsigned int virq, unsigned int nvec); void *platform_msi_get_host_data(struct irq_domain *domain); +void msi_domain_set_default_info_flags(struct msi_domain_info *info); #endif /* CONFIG_GENERIC_MSI_IRQ_DOMAIN */ #ifdef CONFIG_PCI_MSI_IRQ_DOMAIN
diff --git a/kernel/irq/msi.c b/kernel/irq/msi.c
index b338d62..c54316d 100644
--- a/kernel/irq/msi.c
+++ b/kernel/irq/msi.c@@ -70,6 +70,30 @@ void get_cached_msi_msg(unsigned int irq, struct msi_msg *msg) EXPORT_SYMBOL_GPL(get_cached_msi_msg); #ifdef CONFIG_GENERIC_MSI_IRQ_DOMAIN +void msi_domain_set_default_info_flags(struct msi_domain_info *info) +{ + /* Required so that a device latches a valid MSI message on startup */ + info->flags |= MSI_FLAG_ACTIVATE_EARLY; + + /* + * Interrupt reservation mode allows to stear the MSI message of an + * inactive device to a special (usually spurious interrupt) target. + * This allows to prevent interrupt vector exhaustion e.g. on x86. + * But (PCI)MSI interrupts are activated early - see above - so the + * interrupt request/startup sequence would not try to allocate a + * usable vector which means that the device interrupts would end + * up on the special vector and issue spurious interrupt messages. + * Setting the reactivation flag ensures that when the interrupt + * is requested the activation is invoked again so that a real + * vector can be allocated. + */ + if (IS_ENABLED(CONFIG_GENERIC_IRQ_RESERVATION_MODE)) + info->flags |= MSI_FLAG_MUST_REACTIVATE; + + /* MSI is oneshot-safe at least in theory */ + info->chip->flags |= IRQCHIP_ONESHOT_SAFE; +} + static inline void irq_chip_write_msi_msg(struct irq_data *data, struct msi_msg *msg) {
--
2.7.4