[patch 08/10] PCI/MSI: Provide pci_msi_domain_supports_expand()

Thomas Gleixner
2021-11-27T01:33:54Z

Not all irq domain implementations can support runtime MSI-X vector
expansion as they assume zero based allocations or have other
restrictions.

The legacy PCI allocation functions are not suited for runtime vector
expansion either.

Add a function which allows to query whether runtime MSI-X vector expansion
is supported or not.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
drivers/pci/msi/irqdomain.c | 29 +++++++++++++++++++++++------
include/linux/msi.h | 2 ++
2 files changed, 25 insertions(+), 6 deletions(-)

--- a/drivers/pci/msi/irqdomain.c
+++ b/drivers/pci/msi/irqdomain.c
@@ -8,12 +8,18 @@

#include "msi.h"

+static struct irq_domain *pci_get_msi_domain(struct pci_dev *dev)
+{
+ struct irq_domain *domain = dev_get_msi_domain(&dev->dev);
+
+ return domain && irq_domain_is_hierarchy(domain) ? domain : NULL;
+}
+
int pci_msi_setup_msi_irqs(struct pci_dev *dev, struct msi_range *range, int type)
{
- struct irq_domain *domain;
+ struct irq_domain *domain = pci_get_msi_domain(dev);

- domain = dev_get_msi_domain(&dev->dev);
- if (domain && irq_domain_is_hierarchy(domain))
+ if (domain)
return msi_domain_alloc_irqs_descs_locked(domain, &dev->dev, range);

return pci_msi_legacy_setup_msi_irqs(dev, range->ndesc, type);
@@ -21,15 +27,26 @@ int pci_msi_setup_msi_irqs(struct pci_de

void pci_msi_teardown_msi_irqs(struct pci_dev *dev, struct msi_range *range)
{
- struct irq_domain *domain;
+ struct irq_domain *domain = pci_get_msi_domain(dev);

- domain = dev_get_msi_domain(&dev->dev);
- if (domain && irq_domain_is_hierarchy(domain))
+ if (domain)
msi_domain_free_irqs_descs_locked(domain, &dev->dev, range);
else
pci_msi_legacy_teardown_msi_irqs(dev);
}

+bool pci_msi_domain_supports_expand(struct pci_dev *dev)
+{
+ struct irq_domain *domain = pci_get_msi_domain(dev);
+ struct msi_domain_info *info;
+
+ if (!domain)
+ return false;
+
+ info = domain->host_data;
+ return info->flags & MSI_FLAG_CAN_EXPAND;
+}
+
/**
* pci_msi_domain_write_msg - Helper to write MSI message to PCI config space
* @irq_data: Pointer to interrupt data of the MSI interrupt
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -552,11 +552,13 @@ struct irq_domain *pci_msi_create_irq_do
u32 pci_msi_domain_get_msi_rid(struct irq_domain *domain, struct pci_dev *pdev);
struct irq_domain *pci_msi_get_device_domain(struct pci_dev *pdev);
bool pci_dev_has_special_msi_domain(struct pci_dev *pdev);
+bool pci_msi_domain_supports_expand(struct pci_dev *dev);
#else
static inline struct irq_domain *pci_msi_get_device_domain(struct pci_dev *pdev)
{
return NULL;
}
+static inline bool pci_msi_domain_supports_expand(struct pci_dev *dev) { return false; }
#endif /* CONFIG_PCI_MSI_IRQ_DOMAIN */

#endif /* LINUX_MSI_H */