From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Thu, 22 Mar 2018 16:22:35 +0100
Subject: iommu/amd: Split domain id out of amd_iommu_devtable_lock
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git
Git-commit: a537ff56051d8e2b3030c3ca3f37c4688df9cebc
Patch-mainline: Queued in subsystem maintainer repository
References: SLE Realtime Extension

Upstream commit 2bc00180890427dcc092b2f2b0d03c904bcade29

domain_id_alloc() and domain_id_free() is used for id management. Those
two function share a bitmap (amd_iommu_pd_alloc_bitmap) and set/clear
bits based on id allocation. There is no need to share this with
amd_iommu_devtable_lock, it can use its own lock for this operation.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Mike Galbraith <mgalbraith@suse.de>
---
 drivers/iommu/amd_iommu.c |   12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -80,6 +80,7 @@
 #define AMD_IOMMU_PGSIZES	((~0xFFFUL) & ~(2ULL << 38))
 
 static DEFINE_RWLOCK(amd_iommu_devtable_lock);
+static DEFINE_SPINLOCK(pd_bitmap_lock);
 
 /* List of all available dev_data structures */
 static LLIST_HEAD(dev_data_list);
@@ -1637,29 +1638,26 @@ static void del_domain_from_list(struct
 
 static u16 domain_id_alloc(void)
 {
-	unsigned long flags;
 	int id;
 
-	write_lock_irqsave(&amd_iommu_devtable_lock, flags);
+	spin_lock(&pd_bitmap_lock);
 	id = find_first_zero_bit(amd_iommu_pd_alloc_bitmap, MAX_DOMAIN_ID);
 	BUG_ON(id == 0);
 	if (id > 0 && id < MAX_DOMAIN_ID)
 		__set_bit(id, amd_iommu_pd_alloc_bitmap);
 	else
 		id = 0;
-	write_unlock_irqrestore(&amd_iommu_devtable_lock, flags);
+	spin_unlock(&pd_bitmap_lock);
 
 	return id;
 }
 
 static void domain_id_free(int id)
 {
-	unsigned long flags;
-
-	write_lock_irqsave(&amd_iommu_devtable_lock, flags);
+	spin_lock(&pd_bitmap_lock);
 	if (id > 0 && id < MAX_DOMAIN_ID)
 		__clear_bit(id, amd_iommu_pd_alloc_bitmap);
-	write_unlock_irqrestore(&amd_iommu_devtable_lock, flags);
+	spin_unlock(&pd_bitmap_lock);
 }
 
 #define DEFINE_FREE_PT_FN(LVL, FN)				\