On 24/08/18 12:38, Robin Murphy wrote:
On 24/08/18 07:53, Christoph Hellwig wrote:
We need to take the DMA offset and encryption bit into account when
selecting
a zone. Add a helper that takes those into account and use it.
Signed-off-by: Christoph Hellwig <[email protected]>
---
kernel/dma/direct.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index de87b0282e74..3f8b596ea393 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -58,6 +58,14 @@ static bool dma_coherent_ok(struct device *dev,
phys_addr_t phys, size_t size)
return addr + size - 1 <= dev->coherent_dma_mask;
}
+static bool dma_coherent_below(struct device *dev, u64 mask)
+{
+ dma_addr_t addr = force_dma_unencrypted() ?
+ __phys_to_dma(dev, mask) : phys_to_dma(dev, mask);
+
+ return dev->coherent_dma_mask <= addr;
+}
+
void *dma_direct_alloc(struct device *dev, size_t size, dma_addr_t
*dma_handle,
gfp_t gfp, unsigned long attrs)
{
@@ -70,9 +78,9 @@ void *dma_direct_alloc(struct device *dev, size_t
size, dma_addr_t *dma_handle,
gfp &= ~__GFP_ZERO;
/* GFP_DMA32 and GFP_DMA are no ops without the corresponding
zones: */
- if (dev->coherent_dma_mask <= DMA_BIT_MASK(ARCH_ZONE_DMA_BITS))
+ if (dma_coherent_below(dev, DMA_BIT_MASK(ARCH_ZONE_DMA_BITS)))
gfp |= GFP_DMA;
- if (dev->coherent_dma_mask <= DMA_BIT_MASK(32) && !(gfp & GFP_DMA))
+ if (dma_coherent_below(dev, DMA_BIT_MASK(32) && !(gfp & GFP_DMA)))
gfp |= GFP_DMA32;
again:
@@ -93,14 +101,14 @@ void *dma_direct_alloc(struct device *dev, size_t
size, dma_addr_t *dma_handle,
page = NULL;
if (IS_ENABLED(CONFIG_ZONE_DMA32) &&
- dev->coherent_dma_mask < DMA_BIT_MASK(64) &&
We're effectively changing the "<" into a "<="...
+ dma_coherent_below(dev, DMA_BIT_MASK(64)) &&
...which I think means this check now *always* returns true...
Although on closer inspection that was effectively already the case - we
could never get here if dev->coherent_dma_mask == DMA_BIT_MASK(64),
because dma_coherent_ok() couldn't possibly have returned false in the
first place. So this one was always unnecessary.
Robin.
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