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| author | Jisheng Zhang <jszhang@kernel.org> | 2024-03-25 12:00:36 +0100 |
|---|---|---|
| committer | Palmer Dabbelt <palmer@rivosinc.com> | 2024-04-30 19:35:45 +0200 |
| commit | dcb2743d1e701fc1a986c187adc11f6148316d21 (patch) | |
| tree | 33263065e01dc2f7af6fda2665cabb2cf903399c /arch/riscv/mm | |
| parent | riscv: Annotate pgtable_l{4,5}_enabled with __ro_after_init (diff) | |
| download | linux-dcb2743d1e701fc1a986c187adc11f6148316d21.tar.xz linux-dcb2743d1e701fc1a986c187adc11f6148316d21.zip | |
riscv: mm: still create swiotlb buffer for kmalloc() bouncing if required
After commit f51f7a0fc2f4 ("riscv: enable DMA_BOUNCE_UNALIGNED_KMALLOC
for !dma_coherent"), for non-coherent platforms with less than 4GB
memory, we rely on users to pass "swiotlb=mmnn,force" kernel parameters
to enable DMA bouncing for unaligned kmalloc() buffers. Now let's go
further: If no bouncing needed for ZONE_DMA, let kernel automatically
allocate 1MB swiotlb buffer per 1GB of RAM for kmalloc() bouncing on
non-coherent platforms, so that no need to pass "swiotlb=mmnn,force"
any more.
The math of "1MB swiotlb buffer per 1GB of RAM for kmalloc() bouncing"
is taken from arm64. Users can still force smaller swiotlb buffer by
passing "swiotlb=mmnn".
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/r/20240325110036.1564-1-jszhang@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Diffstat (limited to 'arch/riscv/mm')
| -rw-r--r-- | arch/riscv/mm/init.c | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c index 8631b33368ec..2574f6a3b0e7 100644 --- a/arch/riscv/mm/init.c +++ b/arch/riscv/mm/init.c @@ -161,11 +161,25 @@ static void print_vm_layout(void) { } void __init mem_init(void) { + bool swiotlb = max_pfn > PFN_DOWN(dma32_phys_limit); #ifdef CONFIG_FLATMEM BUG_ON(!mem_map); #endif /* CONFIG_FLATMEM */ - swiotlb_init(max_pfn > PFN_DOWN(dma32_phys_limit), SWIOTLB_VERBOSE); + if (IS_ENABLED(CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC) && !swiotlb && + dma_cache_alignment != 1) { + /* + * If no bouncing needed for ZONE_DMA, allocate 1MB swiotlb + * buffer per 1GB of RAM for kmalloc() bouncing on + * non-coherent platforms. + */ + unsigned long size = + DIV_ROUND_UP(memblock_phys_mem_size(), 1024); + swiotlb_adjust_size(min(swiotlb_size_or_default(), size)); + swiotlb = true; + } + + swiotlb_init(swiotlb, SWIOTLB_VERBOSE); memblock_free_all(); print_vm_layout(); |