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Subject[PATCH 1/3] arm64/mm: Simplify SWIOTLB setup in arch_mm_preinit()
From
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>
---
arch/arm64/mm/init.c | 11 ++++-------
1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 97987f850a33..fcc9c05a8fe6 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -336,25 +336,22 @@ 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);
+ bool limited_addressing = 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 (!limited_addressing) {
/*
* 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
--
2.54.0.1032.g2f8565e1d1-goog

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