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genirq: Use a maple tree for interrupt descriptor management 

The current implementation uses a static bitmap for interrupt descriptor
allocation and a radix tree to pointer store the pointer for lookup.

However, the size of the bitmap is constrained by the build time macro
MAX_SPARSE_IRQS, which may not be sufficient to support high-end servers,
particularly those with GICv4.1 hardware, which require a large interrupt
space to cover LPIs and vSGIs.

Replace the bitmap and the radix tree with a maple tree, which not only
stores pointers for lookup, but also provides a mechanism to find free
ranges. That removes the build time hardcoded upper limit.

Signed-off-by: Shanker Donthineni <sdonthineni@nvidia.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20230519134902.1495562-4-sdonthineni@nvidia.com
This commit is contained in:
Shanker Donthineni 2023-05-19 08:49:02 -05:00 committed by Thomas Gleixner
parent 5e630aa8d9
commit 721255b982
2 changed files with 33 additions and 26 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
kernel/irq/internals.h
View File

@ -12,7 +12,7 @@
#include <linux/sched/clock.h>
#ifdef CONFIG_SPARSE_IRQ
# define MAX_SPARSE_IRQS (NR_IRQS + 8196)
# define MAX_SPARSE_IRQS INT_MAX
#else
# define MAX_SPARSE_IRQS NR_IRQS
#endif

57
kernel/irq/irqdesc.c
View File

@ -12,8 +12,7 @@
#include <linux/export.h>
#include <linux/interrupt.h>
#include <linux/kernel_stat.h>
#include <linux/radix-tree.h>
#include <linux/bitmap.h>
#include <linux/maple_tree.h>
#include <linux/irqdomain.h>
#include <linux/sysfs.h>
@ -131,17 +130,39 @@ int nr_irqs = NR_IRQS;
EXPORT_SYMBOL_GPL(nr_irqs);
static DEFINE_MUTEX(sparse_irq_lock);
static DECLARE_BITMAP(allocated_irqs, MAX_SPARSE_IRQS);
static struct maple_tree sparse_irqs = MTREE_INIT_EXT(sparse_irqs,
MT_FLAGS_ALLOC_RANGE |
MT_FLAGS_LOCK_EXTERN |
MT_FLAGS_USE_RCU,
sparse_irq_lock);
static int irq_find_free_area(unsigned int from, unsigned int cnt)
{
return bitmap_find_next_zero_area(allocated_irqs, MAX_SPARSE_IRQS,
from, cnt, 0);
MA_STATE(mas, &sparse_irqs, 0, 0);
if (mas_empty_area(&mas, from, MAX_SPARSE_IRQS, cnt))
return -ENOSPC;
return mas.index;
}
static unsigned int irq_find_at_or_after(unsigned int offset)
{
return find_next_bit(allocated_irqs, nr_irqs, offset);
unsigned long index = offset;
struct irq_desc *desc = mt_find(&sparse_irqs, &index, nr_irqs);
return desc ? irq_desc_get_irq(desc) : nr_irqs;
}
static void irq_insert_desc(unsigned int irq, struct irq_desc *desc)
{
MA_STATE(mas, &sparse_irqs, irq, irq);
WARN_ON(mas_store_gfp(&mas, desc, GFP_KERNEL) != 0);
}
static void delete_irq_desc(unsigned int irq)
{
MA_STATE(mas, &sparse_irqs, irq, irq);
mas_erase(&mas);
}
#ifdef CONFIG_SPARSE_IRQ
@ -355,26 +376,14 @@ static void irq_sysfs_del(struct irq_desc *desc) {}
#endif /* CONFIG_SYSFS */
static RADIX_TREE(irq_desc_tree, GFP_KERNEL);
static void irq_insert_desc(unsigned int irq, struct irq_desc *desc)
{
radix_tree_insert(&irq_desc_tree, irq, desc);
}
struct irq_desc *irq_to_desc(unsigned int irq)
{
return radix_tree_lookup(&irq_desc_tree, irq);
return mtree_load(&sparse_irqs, irq);
}
#ifdef CONFIG_KVM_BOOK3S_64_HV_MODULE
EXPORT_SYMBOL_GPL(irq_to_desc);
#endif
static void delete_irq_desc(unsigned int irq)
{
radix_tree_delete(&irq_desc_tree, irq);
}
#ifdef CONFIG_SMP
static void free_masks(struct irq_desc *desc)
{
@ -517,7 +526,6 @@ static int alloc_descs(unsigned int start, unsigned int cnt, int node,
irq_sysfs_add(start + i, desc);
irq_add_debugfs_entry(start + i, desc);
}
bitmap_set(allocated_irqs, start, cnt);
return start;
err:
@ -557,7 +565,6 @@ int __init early_irq_init(void)
for (i = 0; i < initcnt; i++) {
desc = alloc_desc(i, node, 0, NULL, NULL);
set_bit(i, allocated_irqs);
irq_insert_desc(i, desc);
}
return arch_early_irq_init();
@ -612,6 +619,7 @@ static void free_desc(unsigned int irq)
raw_spin_lock_irqsave(&desc->lock, flags);
desc_set_defaults(irq, desc, irq_desc_get_node(desc), NULL, NULL);
raw_spin_unlock_irqrestore(&desc->lock, flags);
delete_irq_desc(irq);
}
static inline int alloc_descs(unsigned int start, unsigned int cnt, int node,
@ -624,8 +632,8 @@ static inline int alloc_descs(unsigned int start, unsigned int cnt, int node,
struct irq_desc *desc = irq_to_desc(start + i);
desc->owner = owner;
irq_insert_desc(start + i, desc);
}
bitmap_set(allocated_irqs, start, cnt);
return start;
}
@ -637,7 +645,7 @@ static int irq_expand_nr_irqs(unsigned int nr)
void irq_mark_irq(unsigned int irq)
{
mutex_lock(&sparse_irq_lock);
bitmap_set(allocated_irqs, irq, 1);
irq_insert_desc(irq, irq_desc + irq);
mutex_unlock(&sparse_irq_lock);
}
@ -781,7 +789,6 @@ void irq_free_descs(unsigned int from, unsigned int cnt)
for (i = 0; i < cnt; i++)
free_desc(from + i);
bitmap_clear(allocated_irqs, from, cnt);
mutex_unlock(&sparse_irq_lock);
}
EXPORT_SYMBOL_GPL(irq_free_descs);
@ -844,7 +851,7 @@ EXPORT_SYMBOL_GPL(__irq_alloc_descs);
* irq_get_next_irq - get next allocated irq number
* @offset: where to start the search
*
* Returns next irq number at or after offset or nr_irqs if none is found.
* Returns next irq number after offset or nr_irqs if none is found.
*/
unsigned int irq_get_next_irq(unsigned int offset)
{