linux-kernel - Re: [PATCH 08/11] x86/mm: enable broadcast TLB invalidation for multi-threaded processes

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Message-Id: <08542B0E-71E2-4DC5-8C9F-5C09F0376A50@gmail.com>
Date: Thu, 26 Dec 2024 01:32:58 +0200
From: Nadav Amit <nadav.amit@...il.com>
To: Rik van Riel <riel@...riel.com>
Cc: the arch/x86 maintainers <x86@...nel.org>,
 Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
 kernel-team@...a.com,
 Dave Hansen <dave.hansen@...ux.intel.com>,
 luto@...nel.org,
 peterz@...radead.org,
 Thomas Gleixner <tglx@...utronix.de>,
 Ingo Molnar <mingo@...hat.com>,
 Borislav Petkov <bp@...en8.de>,
 "H. Peter Anvin" <hpa@...or.com>,
 Andrew Morton <akpm@...ux-foundation.org>,
 "open list:MEMORY MANAGEMENT" <linux-mm@...ck.org>
Subject: Re: [PATCH 08/11] x86/mm: enable broadcast TLB invalidation for
 multi-threaded processes

> 
> 
> On 23 Dec 2024, at 4:55, Rik van Riel <riel@...riel.com> wrote:
> 
> @@ -1049,9 +1341,12 @@ void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
> 	 * a local TLB flush is needed. Optimize this use-case by calling
> 	 * flush_tlb_func_local() directly in this case.
> 	 */
> -	if (cpumask_any_but(mm_cpumask(mm), cpu) < nr_cpu_ids) {
> +	if (IS_ENABLED(CONFIG_CPU_SUP_AMD) && mm->context.broadcast_asid) {
> +		broadcast_tlb_flush(info);
> 

I think broadcast_asid is defined within an ifdef, so the IS_ENABLED() here
would not save you from having to use ifdef.