linux-kernel - Re: [PATCH v3 6/7] riscv: add a data fence for CMODX in the kernel mode

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] [day] [month] [year] [list]

Message-ID: <Z9B8vgdTq1M9r3_k@andrea>
Date: Tue, 11 Mar 2025 19:11:10 +0100
From: Andrea Parri <parri.andrea@...il.com>
To: Björn Töpel <bjorn@...nel.org>
Cc: Andy Chiu <andybnac@...il.com>,
	Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>, linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org, bjorn@...osinc.com,
	puranjay12@...il.com, alexghiti@...osinc.com,
	yongxuan.wang@...ive.com, greentime.hu@...ive.com,
	nick.hu@...ive.com, nylon.chen@...ive.com, tommy.wu@...ive.com,
	eric.lin@...ive.com, viccent.chen@...ive.com, zong.li@...ive.com,
	samuel.holland@...ive.com
Subject: Re: [PATCH v3 6/7] riscv: add a data fence for CMODX in the kernel
 mode

On Tue, Mar 11, 2025 at 03:53:36PM +0100, Björn Töpel wrote:
> Andrea Parri <parri.andrea@...il.com> writes:
> 
> >> FWIW, the for S-IMSIC the write is already writel(), so we'll have the
> >> text patching and IPI ordered. Regardless, there's more than one flavor
> >> of IPI on RISC-V!
> >
> > AFAIU, this writel() is intended to order the insertion (and the initialization)
> > of the CSD object before the MMIO writes; so, the "right fix" seems to turn the
> > "other flavors" into using a writel() or providing a similar ordering guarantee.
> 
> Yes, that's probably the right approach, or maybe follow-up!
> 
> > As a bonus, such change should address/fix all current and future occurrences of
> > the message-passing scenario in question (the patch addressed the occurrence in
> > flush_icache_all(), but there appears to be a similar one in flush_icache_mm()).
> 
> Indeed. I wonder if the SBI remote fence.i needs it?

Ah!  So I am not alone: AFAICT, that remains a matter of discussions with your SEE
team/developers.  :-|

  Andrea