Messages in this thread Patch in this message | ![/](/images/icornerl.gif) | | From | Jia He <> | Subject | [PATCH v3 2/2] dma-mapping: fix dma_addressing_limited() if dma_range_map can't cover all system RAM | Date | Mon, 16 Oct 2023 12:52:54 +0000 |
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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: Jia He <justin.he@arm.com> --- kernel/dma/mapping.c | 49 ++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 47 insertions(+), 2 deletions(-)
diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c index 5bfe782f9a7f..9889d1d25a7f 100644 --- a/kernel/dma/mapping.c +++ b/kernel/dma/mapping.c @@ -7,6 +7,7 @@ */ #include <linux/memblock.h> /* for max_pfn */ #include <linux/acpi.h> +#include <linux/dma-direct.h> /* for bus_dma_region */ #include <linux/dma-map-ops.h> #include <linux/export.h> #include <linux/gfp.h> @@ -793,6 +794,47 @@ int dma_set_coherent_mask(struct device *dev, u64 mask) } EXPORT_SYMBOL(dma_set_coherent_mask); +/* + * To check whether all ram resource ranges are covered by dma range map + * Returns 0 when continuous 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; + struct device *dev = (struct device *)data; + struct bus_dma_region *bdr = NULL; + const struct bus_dma_region *m; + + 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 = (struct bus_dma_region *)m; + break; + } + } + if (!bdr) + return 1; + + start_pfn = PFN_DOWN(bdr->cpu_start) + PFN_DOWN(bdr->size); + } + + return 0; +} + +static bool all_ram_in_dma_range_map(struct device *dev) +{ + if (!dev->dma_range_map) + return 1; + + return !walk_system_ram_range(0, PFN_DOWN(ULONG_MAX) + 1, dev, + check_ram_in_range_map); +} + /** * dma_addressing_limited - return if the device is addressing limited * @dev: device to check @@ -803,8 +845,11 @@ 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); + if (min_not_zero(dma_get_mask(dev), dev->bus_dma_limit) < + dma_get_required_mask(dev)) + return true; + + return !all_ram_in_dma_range_map(dev); } EXPORT_SYMBOL(dma_addressing_limited); -- 2.25.1
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