Messages in this thread Patch in this message |  | | Date | Wed, 3 Jun 2026 15:27:52 +0300 | | From | Mike Rapoport <> | | Subject | Re: [PATCH 1/3] arm64/mm: Simplify SWIOTLB setup in arch_mm_preinit() |
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Hi,
On Wed, Jun 03, 2026 at 11:05:20AM +0000, Mostafa Saleh wrote: > 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) {
Can realm_world() coexist with limited_addressing? Then the size adjustment is still required.
I'd also make this more explicit:
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 > -- > 2.54.0.1032.g2f8565e1d1-goog >
-- Sincerely yours, Mike.
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