Re: [PATCH v3] arm64: hugetlb: enable __HAVE_ARCH_FLUSH_HUGETLB_TLB_RANGE

[Catalin Marinas <catalin.marinas@arm.com>]

On Tue, Aug 01, 2023 at 09:56:16PM +0800, Kefeng Wang wrote:
> +#define __HAVE_ARCH_FLUSH_HUGETLB_TLB_RANGE
> +static inline void flush_hugetlb_tlb_range(struct vm_area_struct *vma,
> +					   unsigned long start,
> +					   unsigned long end)
> +{
> +	unsigned long stride = huge_page_size(hstate_vma(vma));
> +
> +	switch (stride) {
> +#ifndef __PAGETABLE_PMD_FOLDED
> +	case PUD_SIZE:
> +		flush_pud_tlb_range(vma, start, end);
> +		break;
> +#endif
> +	case PMD_SIZE:
> +		flush_pmd_tlb_range(vma, start, end);
> +		break;
> +	default:
> +		__flush_tlb_range(vma, start, end, PAGE_SIZE, false, 0);
> +	}
> +}

I think we should be consistent and either use __flush_tlb_range()
everywhere or flush_p*d_tlb_range() together with flush_tlb_range().
Maybe using __flush_tlb_range() for the pmd/pud is not too bad, smaller
patch.

That said, I'd avoid the #ifndef and just go for an if/else statement:

	if (stride == PMD_SIZE)
		__flush_tlb_range(vma, start, end, stride, false, 2);
	else if (stride == PUD_SIZE)
		__flush_tlb_range(vma, start, end, stride, false, 1);
	else
		__flush_tlb_range(vma, start, end, PAGE_SIZE, 0);

With the pmd folded, the P*D_SIZE is the same and the compiler should
eliminate the second branch.

-- 
Catalin