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genirq/irqdomain: Provide IRQ_DOMAIN_FLAG_MSI_PARENT

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The new PCI/IMS (Interrupt Message Store) functionality is allowing
hardware vendors to provide implementation specific storage for the MSI
messages. This can be device memory and also host/guest memory, e.g. in
queue memory which is shared with the hardware.

This requires device specific MSI interrupt domains, which cannot be
achieved by expanding the existing PCI/MSI interrupt domain concept which is
a global interrupt domain shared by all PCI devices on a particular (IOMMU)
segment:

                                         |--- device 1
     [Vector]---[Remapping]---[PCI/MSI]--|...
                                         |--- device N

This works because the PCI/MSI[-X] space is uniform, but falls apart with
PCI/IMS which is implementation defined and must be available along with
PCI/MSI[-X] on the same device.

To support PCI/MSI[-X] plus PCI/IMS on the same device it is required to
rework the PCI/MSI interrupt domain hierarchy concept in the following way:

                              |--- [PCI/MSI] device 1
     [Vector]---[Remapping]---|...
                              |--- [PCI/MSI] device N

That allows in the next step to create multiple interrupt domains per device:


                              |--- [PCI/MSI] device 1
                              |--- [PCI/IMS] device 1
     [Vector]---[Remapping]---|...
                              |--- [PCI/MSI] device N
                              |--- [PCI/IMS] device N

So the domain which previously created the global PCI/MSI domain must now
act as parent domain for the per device domains.

The hierarchy depth is the same as before, but the PCI/MSI domains are then
device specific and not longer global.

Provide IRQ_DOMAIN_FLAG_MSI_PARENT, which allows to identify these parent
domains, along with helpers to query it.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221124230313.690038274@linutronix.de
This commit is contained in:
Thomas Gleixner
2022-11-25 00:24:15 +01:00
parent 6b6941f665
commit b749e6d31c
1 changed files with 14 additions and 0 deletions
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14
include/linux/irqdomain.h
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@@ -189,6 +189,9 @@ enum {
/* Irq domain doesn't translate anything */
IRQ_DOMAIN_FLAG_NO_MAP = (1 << 6),
/* Irq domain is a MSI parent domain */
IRQ_DOMAIN_FLAG_MSI_PARENT = (1 << 8),
/*
* Flags starting from IRQ_DOMAIN_FLAG_NONCORE are reserved
* for implementation specific purposes and ignored by the
@@ -551,6 +554,11 @@ static inline bool irq_domain_is_msi_remap(struct irq_domain *domain)
extern bool irq_domain_hierarchical_is_msi_remap(struct irq_domain *domain);
static inline bool irq_domain_is_msi_parent(struct irq_domain *domain)
{
return domain->flags & IRQ_DOMAIN_FLAG_MSI_PARENT;
}
#else /* CONFIG_IRQ_DOMAIN_HIERARCHY */
static inline int irq_domain_alloc_irqs(struct irq_domain *domain,
unsigned int nr_irqs, int node, void *arg)
@@ -596,6 +604,12 @@ irq_domain_hierarchical_is_msi_remap(struct irq_domain *domain)
{
return false;
}
static inline bool irq_domain_is_msi_parent(struct irq_domain *domain)
{
return false;
}
#endif /* CONFIG_IRQ_DOMAIN_HIERARCHY */
#else /* CONFIG_IRQ_DOMAIN */