linux-kernel - [PATCH 04/10] iommu/amd: split irq_lookup_table out of the amd_iommu_devtable

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Date:   Fri, 16 Mar 2018 21:18:30 +0100
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     Joerg Roedel <joro@...tes.org>
Cc:     iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        tglx@...utronix.de,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: [PATCH 04/10] iommu/amd: split irq_lookup_table out of the amd_iommu_devtable_lock

The function get_irq_table() reads/writes irq_lookup_table while holding
the amd_iommu_devtable_lock. It also modifies
amd_iommu_dev_table[].data[2].
set_dte_entry() is using amd_iommu_dev_table[].data[0|1] (under the
domain->lock) so it should be okay. The access to the iommu is
serialized with its own (iommu's) lock.

So split out get_irq_table() out of amd_iommu_devtable_lock's lock. The
new lock is a raw_spin_lock because modify_irte_ga() is called while
desc->lock is held (which is raw).

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
 drivers/iommu/amd_iommu.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 692b2e3b9af1..5191319d9f0a 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -82,6 +82,7 @@
 
 static DEFINE_RWLOCK(amd_iommu_devtable_lock);
 static DEFINE_SPINLOCK(pd_bitmap_lock);
+static DEFINE_RAW_SPINLOCK(iommu_table_lock);
 
 /* List of all available dev_data structures */
 static LLIST_HEAD(dev_data_list);
@@ -3623,7 +3624,7 @@ static struct irq_remap_table *alloc_irq_table(u16 devid, bool ioapic)
 	unsigned long flags;
 	u16 alias;
 
-	write_lock_irqsave(&amd_iommu_devtable_lock, flags);
+	raw_spin_lock_irqsave(&iommu_table_lock, flags);
 
 	iommu = amd_iommu_rlookup_table[devid];
 	if (!iommu)
@@ -3688,7 +3689,7 @@ static struct irq_remap_table *alloc_irq_table(u16 devid, bool ioapic)
 	iommu_completion_wait(iommu);
 
 out_unlock:
-	write_unlock_irqrestore(&amd_iommu_devtable_lock, flags);
+	raw_spin_unlock_irqrestore(&iommu_table_lock, flags);
 
 	return table;
 }
-- 
2.16.2