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Message-Id: <1433486126-23551-14-git-send-email-aik@ozlabs.ru>
Date: Fri, 5 Jun 2015 16:35:05 +1000
From: Alexey Kardashevskiy <aik@...abs.ru>
To: linuxppc-dev@...ts.ozlabs.org
Cc: Alexey Kardashevskiy <aik@...abs.ru>,
Alex Williamson <alex.williamson@...hat.com>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
David Gibson <david@...son.dropbear.id.au>,
Gavin Shan <gwshan@...ux.vnet.ibm.com>,
Paul Mackerras <paulus@...ba.org>,
Wei Yang <weiyang@...ux.vnet.ibm.com>,
linux-kernel@...r.kernel.org
Subject: [PATCH kernel v12 13/34] powerpc/powernv: Do not set "read" flag if direction==DMA_NONE
Normally a bitmap from the iommu_table is used to track what TCE entry
is in use. Since we are going to use iommu_table without its locks and
do xchg() instead, it becomes essential not to put bits which are not
implied in the direction flag as the old TCE value (more precisely -
the permission bits) will be used to decide whether to put the page or not.
This adds iommu_direction_to_tce_perm() (its counterpart is there already)
and uses it for powernv's pnv_tce_build().
Signed-off-by: Alexey Kardashevskiy <aik@...abs.ru>
Reviewed-by: David Gibson <david@...son.dropbear.id.au>
Reviewed-by: Gavin Shan <gwshan@...ux.vnet.ibm.com>
---
Changes:
v9:
* added comment why we must put only valid permission bits
---
arch/powerpc/include/asm/iommu.h | 1 +
arch/powerpc/kernel/iommu.c | 15 +++++++++++++++
arch/powerpc/platforms/powernv/pci.c | 7 +------
3 files changed, 17 insertions(+), 6 deletions(-)
diff --git a/arch/powerpc/include/asm/iommu.h b/arch/powerpc/include/asm/iommu.h
index e94a5e3..d91bd69 100644
--- a/arch/powerpc/include/asm/iommu.h
+++ b/arch/powerpc/include/asm/iommu.h
@@ -200,6 +200,7 @@ extern int iommu_take_ownership(struct iommu_table *tbl);
extern void iommu_release_ownership(struct iommu_table *tbl);
extern enum dma_data_direction iommu_tce_direction(unsigned long tce);
+extern unsigned long iommu_direction_to_tce_perm(enum dma_data_direction dir);
#endif /* __KERNEL__ */
#endif /* _ASM_IOMMU_H */
diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c
index 0019c80..ac2f959 100644
--- a/arch/powerpc/kernel/iommu.c
+++ b/arch/powerpc/kernel/iommu.c
@@ -866,6 +866,21 @@ void iommu_free_coherent(struct iommu_table *tbl, size_t size,
}
}
+unsigned long iommu_direction_to_tce_perm(enum dma_data_direction dir)
+{
+ switch (dir) {
+ case DMA_BIDIRECTIONAL:
+ return TCE_PCI_READ | TCE_PCI_WRITE;
+ case DMA_FROM_DEVICE:
+ return TCE_PCI_WRITE;
+ case DMA_TO_DEVICE:
+ return TCE_PCI_READ;
+ default:
+ return 0;
+ }
+}
+EXPORT_SYMBOL_GPL(iommu_direction_to_tce_perm);
+
#ifdef CONFIG_IOMMU_API
/*
* SPAPR TCE API
diff --git a/arch/powerpc/platforms/powernv/pci.c b/arch/powerpc/platforms/powernv/pci.c
index bca2aeb..b7ea245 100644
--- a/arch/powerpc/platforms/powernv/pci.c
+++ b/arch/powerpc/platforms/powernv/pci.c
@@ -576,15 +576,10 @@ static int pnv_tce_build(struct iommu_table *tbl, long index, long npages,
unsigned long uaddr, enum dma_data_direction direction,
struct dma_attrs *attrs, bool rm)
{
- u64 proto_tce;
+ u64 proto_tce = iommu_direction_to_tce_perm(direction);
__be64 *tcep, *tces;
u64 rpn;
- proto_tce = TCE_PCI_READ; // Read allowed
-
- if (direction != DMA_TO_DEVICE)
- proto_tce |= TCE_PCI_WRITE;
-
tces = tcep = ((__be64 *)tbl->it_base) + index - tbl->it_offset;
rpn = __pa(uaddr) >> tbl->it_page_shift;
--
2.4.0.rc3.8.gfb3e7d5
--
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