Re: [PATCH v7 4/4] arm64/mm: Elide tlbi in contpte_convert() under BBML2

On Thu, Jun 19, 2025 at 08:29:24PM +0100, Catalin Marinas wrote:

On Tue, Jun 17, 2025 at 09:51:04AM +0000, Mikołaj Lenczewski wrote:

quoted

+	if (!system_supports_bbml2_noabort())
+		__flush_tlb_range(&vma, start_addr, addr, PAGE_SIZE, true, 3);
 
 	__set_ptes(mm, start_addr, start_ptep, pte, CONT_PTES);

Eliding the TLBI here is all good but looking at the overall set_ptes(),
why do we bother with unfold+fold for BBML2? Can we not just change
them in place without going through __ptep_get_and_clear()?

Ah, it's unlikely that we'd be able to fold them back if only one pte in
the range was modified, so this optimisation would very rarely/never
trigger. So, for this patch:

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>