Commit a409d960 authored by Jia He's avatar Jia He Committed by Christoph Hellwig
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dma-mapping: fix dma_addressing_limited() if dma_range_map can't cover all system RAM 



There is an unusual case that the range map covers right up to the top
of system RAM, but leaves a hole somewhere lower down. Then it prevents
the nvme device dma mapping in the checking path of phys_to_dma() and
causes the hangs at boot.

E.g. On an Armv8 Ampere server, the dsdt ACPI table is:
 Method (_DMA, 0, Serialized)  // _DMA: Direct Memory Access
            {
                Name (RBUF, ResourceTemplate ()
                {
                    QWordMemory (ResourceConsumer, PosDecode, MinFixed,
MaxFixed, Cacheable, ReadWrite,
                        0x0000000000000000, // Granularity
                        0x0000000000000000, // Range Minimum
                        0x00000000FFFFFFFF, // Range Maximum
                        0x0000000000000000, // Translation Offset
                        0x0000000100000000, // Length
                        ,, , AddressRangeMemory, TypeStatic)
                    QWordMemory (ResourceConsumer, PosDecode, MinFixed,
MaxFixed, Cacheable, ReadWrite,
                        0x0000000000000000, // Granularity
                        0x0000006010200000, // Range Minimum
                        0x000000602FFFFFFF, // Range Maximum
                        0x0000000000000000, // Translation Offset
                        0x000000001FE00000, // Length
                        ,, , AddressRangeMemory, TypeStatic)
                    QWordMemory (ResourceConsumer, PosDecode, MinFixed,
MaxFixed, Cacheable, ReadWrite,
                        0x0000000000000000, // Granularity
                        0x00000060F0000000, // Range Minimum
                        0x00000060FFFFFFFF, // Range Maximum
                        0x0000000000000000, // Translation Offset
                        0x0000000010000000, // Length
                        ,, , AddressRangeMemory, TypeStatic)
                    QWordMemory (ResourceConsumer, PosDecode, MinFixed,
MaxFixed, Cacheable, ReadWrite,
                        0x0000000000000000, // Granularity
                        0x0000007000000000, // Range Minimum
                        0x000003FFFFFFFFFF, // Range Maximum
                        0x0000000000000000, // Translation Offset
                        0x0000039000000000, // Length
                        ,, , AddressRangeMemory, TypeStatic)
                })

But the System RAM ranges are:
cat /proc/iomem |grep -i ram
90000000-91ffffff : System RAM
92900000-fffbffff : System RAM
880000000-fffffffff : System RAM
8800000000-bff5990fff : System RAM
bff59d0000-bff5a4ffff : System RAM
bff8000000-bfffffffff : System RAM
So some RAM ranges are out of dma_range_map.

Fix it by checking whether each of the system RAM resources can be
properly encompassed within the dma_range_map.

Signed-off-by: default avatarJia He <justin.he@arm.com>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
parent 8ae0e970

kernel/dma/direct.c

+40 −0
Original line number Diff line number Diff line
@@ -587,6 +587,46 @@ int dma_direct_supported(struct device *dev, u64 mask) 
	return mask >= phys_to_dma_unencrypted(dev, min_mask);

}



/*

 * To check whether all ram resource ranges are covered by dma range map

 * Returns 0 when further check is needed

 * Returns 1 if there is some RAM range can't be covered by dma_range_map

 */

static int check_ram_in_range_map(unsigned long start_pfn,

				  unsigned long nr_pages, void *data)

{

	unsigned long end_pfn = start_pfn + nr_pages;

	const struct bus_dma_region *bdr = NULL;

	const struct bus_dma_region *m;

	struct device *dev = data;



	while (start_pfn < end_pfn) {

		for (m = dev->dma_range_map; PFN_DOWN(m->size); m++) {

			unsigned long cpu_start_pfn = PFN_DOWN(m->cpu_start);



			if (start_pfn >= cpu_start_pfn &&

			    start_pfn - cpu_start_pfn < PFN_DOWN(m->size)) {

				bdr = m;

				break;

			}

		}

		if (!bdr)

			return 1;



		start_pfn = PFN_DOWN(bdr->cpu_start) + PFN_DOWN(bdr->size);

	}



	return 0;

}



bool dma_direct_all_ram_mapped(struct device *dev)

{

	if (!dev->dma_range_map)

		return true;

	return !walk_system_ram_range(0, PFN_DOWN(ULONG_MAX) + 1, dev,

				      check_ram_in_range_map);

}



size_t dma_direct_max_mapping_size(struct device *dev)

{

	/* If SWIOTLB is active, use its maximum mapping size */

kernel/dma/direct.h

+1 −0
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ int dma_direct_mmap(struct device *dev, struct vm_area_struct *vma, 
bool dma_direct_need_sync(struct device *dev, dma_addr_t dma_addr);

int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl, int nents,

		enum dma_data_direction dir, unsigned long attrs);

bool dma_direct_all_ram_mapped(struct device *dev);

size_t dma_direct_max_mapping_size(struct device *dev);



#if defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_DEVICE) || \

kernel/dma/mapping.c

+9 −2
Original line number Diff line number Diff line
@@ -803,8 +803,15 @@ EXPORT_SYMBOL(dma_set_coherent_mask); 
 */

bool dma_addressing_limited(struct device *dev)

{

	return min_not_zero(dma_get_mask(dev), dev->bus_dma_limit) <

			    dma_get_required_mask(dev);

	const struct dma_map_ops *ops = get_dma_ops(dev);



	if (min_not_zero(dma_get_mask(dev), dev->bus_dma_limit) <

			 dma_get_required_mask(dev))

		return true;



	if (unlikely(ops))

		return false;

	return !dma_direct_all_ram_mapped(dev);

}

EXPORT_SYMBOL_GPL(dma_addressing_limited);