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arm64/mm: Simplify SWIOTLB setup in arch_mm_preinit()

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At the moment, arch_mm_preinit() checks if the system has limited
addressing or is running under CCA to enable SWIOTLB, only after to
be forced to true anyway if it was false due to
CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC being unconditionally true for
arm64.

Simplify this logic, by making it clear that SWIOTLB is always used
but its size depends on the address layout of the system.

Signed-off-by: Mostafa Saleh <smostafa@google.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
Tested-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Mostafa Saleh
2026-06-03 11:05:20 +00:00
committed by Will Deacon
parent 24f55f511b
commit 442d366cc1
1 changed files with 3 additions and 7 deletions
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10
arch/arm64/mm/init.c
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@@ -336,25 +336,21 @@ void __init arch_setup_zero_pages(void)
void __init arch_mm_preinit(void)
{
unsigned int flags = SWIOTLB_VERBOSE;
bool swiotlb = max_pfn > PFN_DOWN(arm64_dma_phys_limit);
if (is_realm_world()) {
swiotlb = true;
flags |= SWIOTLB_FORCE;
}
if (IS_ENABLED(CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC) && !swiotlb) {
} else if (max_pfn <= PFN_DOWN(arm64_dma_phys_limit)) {
/*
* If no bouncing needed for ZONE_DMA, reduce the swiotlb
* buffer for kmalloc() bouncing to 1MB per 1GB of RAM.
*/
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, flags);
swiotlb_init(true, flags);
/*
* Check boundaries twice: Some fundamental inconsistencies can be