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authorSebastian Andrzej Siewior <bigeasy@linutronix.de>2018-03-22 18:22:40 +0300
committerJoerg Roedel <jroedel@suse.de>2018-03-29 11:38:16 +0300
commit993ca6e063a69a0c65ca42ed449b6bc1b3844151 (patch)
tree9a503357e65658e3128f643031fa33d3ae360796 /drivers/iommu
parent2fcc1e8ac4a8514c64f946178fc36c2e30e56a41 (diff)
downloadlinux-993ca6e063a69a0c65ca42ed449b6bc1b3844151.tar.xz
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: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Joerg Roedel <jroedel@suse.de>
Diffstat (limited to 'drivers/iommu')
-rw-r--r--drivers/iommu/amd_iommu.c63
1 files changed, 45 insertions, 18 deletions
diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 11ea2d656be8..c493d345b3ef 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -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;
}