linux-kernel - Re: [PATCH v3] Linux VM workaround for Knights Landing A/D leak

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <6128C99E-3FAA-4925-B68C-16B36178E00B@gmail.com>
Date:	Thu, 16 Jun 2016 09:43:01 -0700
From:	Nadav Amit <nadav.amit@...il.com>
To:	Lukasz Anaczkowski <lukasz.anaczkowski@...el.com>
Cc:	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>, ak@...ux.intel.com,
	kirill.shutemov@...ux.intel.com, mhocko@...e.com,
	akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org, harish.srinivasappa@...el.com,
	lukasz.odzioba@...el.com, grzegorz.andrejczuk@...el.com,
	lukasz.daniluk@...el.com
Subject: Re: [PATCH v3] Linux VM workaround for Knights Landing A/D leak


Lukasz Anaczkowski <lukasz.anaczkowski@...el.com> wrote:

> From: Andi Kleen <ak@...ux.intel.com>
> 
> +void fix_pte_leak(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
> +{
> +	if (cpumask_any_but(mm_cpumask(mm), smp_processor_id()) < nr_cpu_ids) {
> +		trace_tlb_flush(TLB_LOCAL_SHOOTDOWN, TLB_FLUSH_ALL);
This tracing seems incorrect since you don’t perform a local flush.
I don’t think you need any tracing - native_flush_tlb_others will do it for you.

> +		flush_tlb_others(mm_cpumask(mm), mm, addr,
> +				 addr + PAGE_SIZE);
> +		mb();
Why do you need the memory barrier?

Regards,
Nadav