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Commit 993ca6e0 authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Joerg Roedel
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iommu/amd: Drop the lock while allocating new irq remap table 



The irq_remap_table is allocated while the iommu_table_lock is held with
interrupts disabled.
>From looking at the call sites, all callers are in the early device
initialisation (apic_bsp_setup(), pci_enable_device(),
pci_enable_msi()) so make sense to drop the lock which also enables
interrupts and try to allocate that memory with GFP_KERNEL instead
GFP_ATOMIC.

Since during the allocation the iommu_table_lock is dropped, we need to
recheck if table exists after the lock has been reacquired. I *think*
that it is impossible that the "devid" entry appears in irq_lookup_table
while the lock is dropped since the same device can only be probed once.
However I check for both cases, just to be sure.

Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
parent 2fcc1e8a

drivers/iommu/amd_iommu.c

+45 −18
Original line number Diff line number Diff line
@@ -3617,6 +3617,30 @@ static struct irq_remap_table *get_irq_table(u16 devid) 
	return table;

}



static struct irq_remap_table *__alloc_irq_table(void)

{

	struct irq_remap_table *table;



	table = kzalloc(sizeof(*table), GFP_KERNEL);

	if (!table)

		return NULL;



	table->table = kmem_cache_alloc(amd_iommu_irq_cache, GFP_KERNEL);

	if (!table->table) {

		kfree(table);

		return NULL;

	}

	raw_spin_lock_init(&table->lock);



	if (!AMD_IOMMU_GUEST_IR_GA(amd_iommu_guest_ir))

		memset(table->table, 0,

		       MAX_IRQS_PER_TABLE * sizeof(u32));

	else

		memset(table->table, 0,

		       (MAX_IRQS_PER_TABLE * (sizeof(u64) * 2)));

	return table;

}



static void set_remap_table_entry(struct amd_iommu *iommu, u16 devid,

				  struct irq_remap_table *table)

{
@@ -3628,6 +3652,7 @@ static void set_remap_table_entry(struct amd_iommu *iommu, u16 devid, 
static struct irq_remap_table *alloc_irq_table(u16 devid)

{

	struct irq_remap_table *table = NULL;

	struct irq_remap_table *new_table = NULL;

	struct amd_iommu *iommu;

	unsigned long flags;

	u16 alias;
@@ -3646,42 +3671,44 @@ static struct irq_remap_table *alloc_irq_table(u16 devid) 
	table = irq_lookup_table[alias];

	if (table) {

		set_remap_table_entry(iommu, devid, table);

		goto out;

		goto out_wait;

	}

	spin_unlock_irqrestore(&iommu_table_lock, flags);



	/* Nothing there yet, allocate new irq remapping table */

	table = kzalloc(sizeof(*table), GFP_ATOMIC);

	if (!table)

		goto out_unlock;

	new_table = __alloc_irq_table();

	if (!new_table)

		return NULL;



	/* Initialize table spin-lock */

	raw_spin_lock_init(&table->lock);

	spin_lock_irqsave(&iommu_table_lock, flags);



	table->table = kmem_cache_alloc(amd_iommu_irq_cache, GFP_ATOMIC);

	if (!table->table) {

		kfree(table);

		table = NULL;

	table = irq_lookup_table[devid];

	if (table)

		goto out_unlock;

	}



	if (!AMD_IOMMU_GUEST_IR_GA(amd_iommu_guest_ir))

		memset(table->table, 0,

		       MAX_IRQS_PER_TABLE * sizeof(u32));

	else

		memset(table->table, 0,

		       (MAX_IRQS_PER_TABLE * (sizeof(u64) * 2)));

	table = irq_lookup_table[alias];

	if (table) {

		set_remap_table_entry(iommu, devid, table);

		goto out_wait;

	}



	table = new_table;

	new_table = NULL;



	set_remap_table_entry(iommu, devid, table);

	if (devid != alias)

		set_remap_table_entry(iommu, alias, table);



out:

out_wait:

	iommu_completion_wait(iommu);



out_unlock:

	spin_unlock_irqrestore(&iommu_table_lock, flags);



	if (new_table) {

		kmem_cache_free(amd_iommu_irq_cache, new_table->table);

		kfree(new_table);

	}

	return table;

}