Re: [PATCH v1 12/16] arm64/mm: Support huge pte-mapped pages in vmap

On 2/13/25 14:39, Ryan Roberts wrote:

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+#define arch_vmap_pte_range_map_size arch_vmap_pte_range_map_size
+static inline unsigned long arch_vmap_pte_range_map_size(unsigned long addr,
+						unsigned long end, u64 pfn,
+						unsigned int max_page_shift)
+{
+	if (max_page_shift < CONT_PTE_SHIFT)
+		return PAGE_SIZE;
+
+	if (end - addr < CONT_PTE_SIZE)
+		return PAGE_SIZE;
+
+	if (!IS_ALIGNED(addr, CONT_PTE_SIZE))
+		return PAGE_SIZE;
+
+	if (!IS_ALIGNED(PFN_PHYS(pfn), CONT_PTE_SIZE))
+		return PAGE_SIZE;
+
+	return CONT_PTE_SIZE;

A small nit:

Should the rationale behind picking CONT_PTE_SIZE be added here as an in code
comment or something in the function - just to make things bit clear.

I'm not sure what other size we would pick?

The suggestion was to add a small comment in the above helper function explaining
the rationale for various conditions in there while returning either PAGE_SIZE or
CONT_PTE_SIZE to improve readability etc.

OK I've added the following:

/*
 * If the block is at least CONT_PTE_SIZE in size, and is naturally
 * aligned in both virtual and physical space, then we can pte-map the
 * block using the PTE_CONT bit for more efficient use of the TLB.
 */

Sounds good, thanks !