powerpc/iommu: Fix multiple issues with IOMMU pools code

There are a number of issues in the recent IOMMU pools code:

- On a preempt kernel we might switch CPUs in the middle of building
  a scatter gather list. When this happens the handle hint passed in
  no longer falls within the local CPU's pool. Check for this and
  fall back to the pool hint.

- We were missing a spin_unlock/spin_lock in one spot where we
  switch pools.

- We need to provide locking around dart_tlb_invalidate_all and
  dart_tlb_invalidate_one now that the global lock is gone.

Reported-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
CC: <stable@kernel.org> [v3.6]

1 files changed, 12 insertions, 0 deletions

diff --git a/arch/powerpc/sysdev/dart_iommu.c b/arch/powerpc/sysdev/dart_iommu.c
index 8ef63a01e34..bd968a43a48 100644
--- a/arch/powerpc/sysdev/dart_iommu.c
+++ b/arch/powerpc/sysdev/dart_iommu.c
@@ -73,11 +73,16 @@ static int dart_is_u4;
 
 #define DBG(...)
 
+static DEFINE_SPINLOCK(invalidate_lock);
+
 static inline void dart_tlb_invalidate_all(void)
 {
         unsigned long l = 0;
         unsigned int reg, inv_bit;
         unsigned long limit;
+        unsigned long flags;
+
+        spin_lock_irqsave(&invalidate_lock, flags);
 
         DBG("dart: flush\n");
 
@@ -110,12 +115,17 @@ retry:
                         panic("DART: TLB did not flush after waiting a long "
                               "time. Buggy U3 ?");
         }
+
+        spin_unlock_irqrestore(&invalidate_lock, flags);
 }
 
 static inline void dart_tlb_invalidate_one(unsigned long bus_rpn)
 {
         unsigned int reg;
         unsigned int l, limit;
+        unsigned long flags;
+
+        spin_lock_irqsave(&invalidate_lock, flags);
 
         reg = DART_CNTL_U4_ENABLE | DART_CNTL_U4_IONE |
                 (bus_rpn & DART_CNTL_U4_IONE_MASK);
@@ -137,6 +147,8 @@ wait_more:
                         panic("DART: TLB did not flush after waiting a long "
                               "time. Buggy U4 ?");
         }
+
+        spin_unlock_irqrestore(&invalidate_lock, flags);
 }
 
 static void dart_flush(struct iommu_table *tbl)