dma-direct: refine dma_direct_alloc zone selection

We need to take the DMA offset and encryption bit into account when
selecting a zone.  User the opportunity to factor out the zone
selection into a helper for reuse.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>

1 files changed, 21 insertions, 10 deletions

diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index f32b33cfa331..e78548397a92 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -69,6 +69,22 @@ u64 dma_direct_get_required_mask(struct device *dev)
         return (1ULL << (fls64(max_dma) - 1)) * 2 - 1;
 }
 
+static gfp_t __dma_direct_optimal_gfp_mask(struct device *dev, u64 dma_mask,
+                u64 *phys_mask)
+{
+        if (force_dma_unencrypted())
+                *phys_mask = __dma_to_phys(dev, dma_mask);
+        else
+                *phys_mask = dma_to_phys(dev, dma_mask);
+
+        /* GFP_DMA32 and GFP_DMA are no ops without the corresponding zones: */
+        if (*phys_mask <= DMA_BIT_MASK(ARCH_ZONE_DMA_BITS))
+                return GFP_DMA;
+        if (*phys_mask <= DMA_BIT_MASK(32))
+                return GFP_DMA32;
+        return 0;
+}
+
 static bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size)
 {
         return phys_to_dma_direct(dev, phys) + size - 1 <=
@@ -81,17 +97,13 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size,
         unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
         int page_order = get_order(size);
         struct page *page = NULL;
+        u64 phys_mask;
         void *ret;
 
         /* we always manually zero the memory once we are done: */
         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))
-                gfp |= GFP_DMA;
-        if (dev->coherent_dma_mask <= DMA_BIT_MASK(32) && !(gfp & GFP_DMA))
-                gfp |= GFP_DMA32;
-
+        gfp |= __dma_direct_optimal_gfp_mask(dev, dev->coherent_dma_mask,
+                        &phys_mask);
 again:
         /* CMA can be used only in the context which permits sleeping */
         if (gfpflags_allow_blocking(gfp)) {
@@ -110,15 +122,14 @@ again:
                 page = NULL;
 
                 if (IS_ENABLED(CONFIG_ZONE_DMA32) &&
-                    dev->coherent_dma_mask < DMA_BIT_MASK(64) &&
+                    phys_mask < DMA_BIT_MASK(64) &&
                     !(gfp & (GFP_DMA32 | GFP_DMA))) {
                         gfp |= GFP_DMA32;
                         goto again;
                 }
 
                 if (IS_ENABLED(CONFIG_ZONE_DMA) &&
-                    dev->coherent_dma_mask < DMA_BIT_MASK(32) &&
-                    !(gfp & GFP_DMA)) {
+                    phys_mask < DMA_BIT_MASK(32) && !(gfp & GFP_DMA)) {
                         gfp = (gfp & ~GFP_DMA32) | GFP_DMA;
                         goto again;
                 }