dma-direct: implement complete bus_dma_mask handling

Instead of rejecting devices with a too small bus_dma_mask we can handle
by taking the bus dma_mask into account for allocations and bounce
buffering decisions.

Signed-off-by: Christoph Hellwig <hch@lst.de>

1 files changed, 11 insertions, 10 deletions

diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index e78548397a92..60c433b880e0 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -44,10 +44,11 @@ check_addr(struct device *dev, dma_addr_t dma_addr, size_t size,
                         return false;
                 }
 
-                if (*dev->dma_mask >= DMA_BIT_MASK(32)) {
+                if (*dev->dma_mask >= DMA_BIT_MASK(32) || dev->bus_dma_mask) {
                         dev_err(dev,
-                                "%s: overflow %pad+%zu of device mask %llx\n",
-                                caller, &dma_addr, size, *dev->dma_mask);
+                                "%s: overflow %pad+%zu of device mask %llx bus mask %llx\n",
+                                caller, &dma_addr, size,
+                                *dev->dma_mask, dev->bus_dma_mask);
                 }
                 return false;
         }
@@ -66,12 +67,18 @@ u64 dma_direct_get_required_mask(struct device *dev)
 {
         u64 max_dma = phys_to_dma_direct(dev, (max_pfn - 1) << PAGE_SHIFT);
 
+        if (dev->bus_dma_mask && dev->bus_dma_mask < max_dma)
+                max_dma = dev->bus_dma_mask;
+
         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 (dev->bus_dma_mask && dev->bus_dma_mask < dma_mask)
+                dma_mask = dev->bus_dma_mask;
+
         if (force_dma_unencrypted())
                 *phys_mask = __dma_to_phys(dev, dma_mask);
         else
@@ -88,7 +95,7 @@ static gfp_t __dma_direct_optimal_gfp_mask(struct device *dev, u64 dma_mask,
 static bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size)
 {
         return phys_to_dma_direct(dev, phys) + size - 1 <=
-                        dev->coherent_dma_mask;
+                        min_not_zero(dev->coherent_dma_mask, dev->bus_dma_mask);
 }
 
 void *dma_direct_alloc_pages(struct device *dev, size_t size,
@@ -292,12 +299,6 @@ int dma_direct_supported(struct device *dev, u64 mask)
         if (mask < phys_to_dma(dev, DMA_BIT_MASK(32)))
                 return 0;
 #endif
-        /*
-         * Upstream PCI/PCIe bridges or SoC interconnects may not carry
-         * as many DMA address bits as the device itself supports.
-         */
-        if (dev->bus_dma_mask && mask > dev->bus_dma_mask)
-                return 0;
         return 1;
 }