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x86/MSI: Support multiple MSIs in presense of IRQ remapping

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The MSI specification has several constraints in comparison with
MSI-X, most notable of them is the inability to configure MSIs
independently. As a result, it is impossible to dispatch
interrupts from different queues to different CPUs. This is
largely devalues the support of multiple MSIs in SMP systems.

Also, a necessity to allocate a contiguous block of vector
numbers for devices capable of multiple MSIs might cause a
considerable pressure on x86 interrupt vector allocator and
could lead to fragmentation of the interrupt vectors space.

This patch overcomes both drawbacks in presense of IRQ remapping
and lets devices take advantage of multiple queues and per-IRQ
affinity assignments.

Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Matthew Wilcox <willy@linux.intel.com>
Cc: Jeff Garzik <jgarzik@pobox.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/c8bd86ff56b5fc118257436768aaa04489ac0a4c.1353324359.git.agordeev@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Alexander Gordeev
2012-11-19 16:01:29 +01:00
committed by Ingo Molnar
parent 4cca6ea04d
commit 51906e779f
3 changed files with 162 additions and 42 deletions
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34
kernel/irq/chip.c
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@@ -89,6 +89,29 @@ int irq_set_handler_data(unsigned int irq, void *data)
}
EXPORT_SYMBOL(irq_set_handler_data);
/**
* irq_set_msi_desc_off - set MSI descriptor data for an irq at offset
* @irq_base: Interrupt number base
* @irq_offset: Interrupt number offset
* @entry: Pointer to MSI descriptor data
*
* Set the MSI descriptor entry for an irq at offset
*/
int irq_set_msi_desc_off(unsigned int irq_base, unsigned int irq_offset,
struct msi_desc *entry)
{
unsigned long flags;
struct irq_desc *desc = irq_get_desc_lock(irq_base + irq_offset, &flags, IRQ_GET_DESC_CHECK_GLOBAL);
if (!desc)
return -EINVAL;
desc->irq_data.msi_desc = entry;
if (entry && !irq_offset)
entry->irq = irq_base;
irq_put_desc_unlock(desc, flags);
return 0;
}
/**
* irq_set_msi_desc - set MSI descriptor data for an irq
* @irq: Interrupt number
@@ -98,16 +121,7 @@ EXPORT_SYMBOL(irq_set_handler_data);
*/
int irq_set_msi_desc(unsigned int irq, struct msi_desc *entry)
{
unsigned long flags;
struct irq_desc *desc = irq_get_desc_lock(irq, &flags, IRQ_GET_DESC_CHECK_GLOBAL);
if (!desc)
return -EINVAL;
desc->irq_data.msi_desc = entry;
if (entry)
entry->irq = irq;
irq_put_desc_unlock(desc, flags);
return 0;
return irq_set_msi_desc_off(irq, 0, entry);
}
/**