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Subject[PATCH 1/2] iommu/amd: Add align parameter to alloc_irq_index()
Date
From: Joerg Roedel <jroedel@suse.de>

For multi-MSI IRQ ranges the IRQ index needs to be aligned
to the power-of-two of the requested IRQ count. Extend the
alloc_irq_index() function to allow such an allocation.

Reported-by: Thomas Gleixner <tglx@linutronix.de>
Fixes: 2b324506341cb ('iommu/amd: Add routines to manage irq remapping tables')
Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
drivers/iommu/amd_iommu.c | 22 ++++++++++++++--------
1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 51f8215..2d4ee25 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -3660,11 +3660,11 @@ static struct irq_remap_table *get_irq_table(u16 devid, bool ioapic)
return table;
}

-static int alloc_irq_index(u16 devid, int count)
+static int alloc_irq_index(u16 devid, int count, bool align)
{
struct irq_remap_table *table;
+ int index, c, alignment = 1;
unsigned long flags;
- int index, c;
struct amd_iommu *iommu = amd_iommu_rlookup_table[devid];

if (!iommu)
@@ -3674,16 +3674,22 @@ static int alloc_irq_index(u16 devid, int count)
if (!table)
return -ENODEV;

+ if (align)
+ alignment = roundup_pow_of_two(count);
+
spin_lock_irqsave(&table->lock, flags);

/* Scan table for free entries */
- for (c = 0, index = table->min_index;
+ for (index = ALIGN(table->min_index, alignment), c = 0;
index < MAX_IRQS_PER_TABLE;
- ++index) {
- if (!iommu->irte_ops->is_allocated(table, index))
+ index++) {
+ if (!iommu->irte_ops->is_allocated(table, index)) {
c += 1;
- else
- c = 0;
+ } else {
+ c = 0;
+ index = ALIGN(index, alignment);
+ continue;
+ }

if (c == count) {
for (; c != 0; --c)
@@ -4096,7 +4102,7 @@ static int irq_remapping_alloc(struct irq_domain *domain, unsigned int virq,
else
ret = -ENOMEM;
} else {
- index = alloc_irq_index(devid, nr_irqs);
+ index = alloc_irq_index(devid, nr_irqs, false);
}
if (index < 0) {
pr_warn("Failed to allocate IRTE\n");
--
2.7.4
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