linux-kernel - [PATCH kernel v6 16/29] powerpc/iommu: Fix IOMMU ownership control functions

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Message-Id: <1426234057-16165-17-git-send-email-aik@ozlabs.ru>
Date:	Fri, 13 Mar 2015 19:07:24 +1100
From:	Alexey Kardashevskiy <aik@...abs.ru>
To:	linuxppc-dev@...ts.ozlabs.org
Cc:	Alexey Kardashevskiy <aik@...abs.ru>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>,
	Alex Williamson <alex.williamson@...hat.com>,
	kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH kernel v6 16/29] powerpc/iommu: Fix IOMMU ownership control functions

This adds missing locks in iommu_take_ownership()/
iommu_release_ownership().

This marks all pages busy in iommu_table::it_map in order to catch
errors if there is an attempt to use this table while ownership over it
is taken.

This only clears TCE content if there is no page marked busy in it_map.
Clearing must be done outside of the table locks as iommu_clear_tce()
called from iommu_clear_tces_and_put_pages() does this.

Signed-off-by: Alexey Kardashevskiy <aik@...abs.ru>
---
Changes:
v5:
* do not store bit#0 value, it has to be set for zero-based table
anyway
* removed test_and_clear_bit
---
 arch/powerpc/kernel/iommu.c | 26 ++++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c
index 8358631..df888a7 100644
--- a/arch/powerpc/kernel/iommu.c
+++ b/arch/powerpc/kernel/iommu.c
@@ -1052,17 +1052,28 @@ EXPORT_SYMBOL_GPL(iommu_tce_build);
 
 static int iommu_table_take_ownership(struct iommu_table *tbl)
 {
-	unsigned long sz = (tbl->it_size + 7) >> 3;
+	unsigned long flags, i, sz = (tbl->it_size + 7) >> 3;
+	int ret = 0;
+
+	spin_lock_irqsave(&tbl->large_pool.lock, flags);
+	for (i = 0; i < tbl->nr_pools; i++)
+		spin_lock(&tbl->pools[i].lock);
 
 	if (tbl->it_offset == 0)
 		clear_bit(0, tbl->it_map);
 
 	if (!bitmap_empty(tbl->it_map, tbl->it_size)) {
 		pr_err("iommu_tce: it_map is not empty");
-		return -EBUSY;
+		ret = -EBUSY;
+		if (tbl->it_offset == 0)
+			set_bit(0, tbl->it_map);
+	} else {
+		memset(tbl->it_map, 0xff, sz);
 	}
 
-	memset(tbl->it_map, 0xff, sz);
+	for (i = 0; i < tbl->nr_pools; i++)
+		spin_unlock(&tbl->pools[i].lock);
+	spin_unlock_irqrestore(&tbl->large_pool.lock, flags);
 
 	return 0;
 }
@@ -1095,7 +1106,11 @@ EXPORT_SYMBOL_GPL(iommu_take_ownership);
 
 static void iommu_table_release_ownership(struct iommu_table *tbl)
 {
-	unsigned long sz = (tbl->it_size + 7) >> 3;
+	unsigned long flags, i, sz = (tbl->it_size + 7) >> 3;
+
+	spin_lock_irqsave(&tbl->large_pool.lock, flags);
+	for (i = 0; i < tbl->nr_pools; i++)
+		spin_lock(&tbl->pools[i].lock);
 
 	memset(tbl->it_map, 0, sz);
 
@@ -1103,6 +1118,9 @@ static void iommu_table_release_ownership(struct iommu_table *tbl)
 	if (tbl->it_offset == 0)
 		set_bit(0, tbl->it_map);
 
+	for (i = 0; i < tbl->nr_pools; i++)
+		spin_unlock(&tbl->pools[i].lock);
+	spin_unlock_irqrestore(&tbl->large_pool.lock, flags);
 }
 
 extern void iommu_release_ownership(struct iommu_table_group *table_group)
-- 
2.0.0

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