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Shutemov" Cc: Andy Lutomirski , Thomas Gleixner , Ingo Molnar , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Peter Zijlstra , Ard Biesheuvel , "Paul E. McKenney" , Josh Poimboeuf , Xiongwei Song , Xin Li , "Mike Rapoport (IBM)" , Brijesh Singh , Michael Roth , Tony Luck , Alexey Kardashevskiy , Alexander Shishkin , Jonathan Corbet , Sohil Mehta , Ingo Molnar , Pawan Gupta , Daniel Sneddon , Kai Huang , Sandipan Das , Breno Leitao , Rick Edgecombe , Alexei Starovoitov , Hou Tao , Juergen Gross , Vegard Nossum , Kees Cook , Eric Biggers , Jason Gunthorpe , "Masami Hiramatsu (Google)" , Andrew Morton , Luis Chamberlain , Yuntao Wang , Rasmus Villemoes , Christophe Leroy , Tejun Heo , Changbin Du , Huang Shijie , Geert Uytterhoeven , Namhyung Kim , Arnaldo Carvalho de Melo , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-efi@vger.kernel.org, linux-mm@kvack.org, Yian Chen Subject: Re: [PATCHv6 01/16] x86/cpu: Enumerate the LASS feature bits Message-ID: <20250626160707.GGaF1wK5tW37P6xt0O@fat_crate.local> References: <20250620135325.3300848-1-kirill.shutemov@linux.intel.com> <20250620135325.3300848-2-kirill.shutemov@linux.intel.com> <20250620163504.GCaFWNuI-8QFqAM0yI@fat_crate.local> <6y2iqv6c2idn7yebaec7tyhzl5zcsrwqq4lcsokumlqeophzaf@ljnmxorblgcj> <20250620182943.GDaFWolxhwogB2tTxb@fat_crate.local> <20250623102105.GCaFkqkatFSbyl1YeN@fat_crate.local> <20250626151837.GFaF1kzfLtesXLqaAQ@fat_crate.local> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20250626151837.GFaF1kzfLtesXLqaAQ@fat_crate.local> X-Rspam-User: X-Stat-Signature: j5qexaj9p1zcetd3zoxwe5sgxe3mm3e8 X-Rspamd-Queue-Id: 0F0C41C0012 X-Rspamd-Server: rspam08 X-HE-Tag: 1750954092-99848 X-HE-Meta: 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 P8l6brB2 RKYgDYCFxtgM4qFZ66YcmOkwHJXKJea436ABG X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Jun 26, 2025 at 05:18:37PM +0200, Borislav Petkov wrote: > On Mon, Jun 23, 2025 at 04:42:41PM +0300, Kirill A. Shutemov wrote: > > Due to SLAM, we decided to postpone LAM enabling, until LASS is landed. > > > > I am not sure if we want to add static > > /sys/devices/system/cpu/vulnerabilities/slam with "Mitigation: LASS". > > > > There might be other yet-to-be-discovered speculative attacks that LASS > > mitigates. Security features have to visible to userspace independently of > > known vulnerabilities. > > ... and the fact that a vuln is being mitigated by stating that in > /sys/devices/system/cpu/vulnerabilities/ needs to happen too. > > I'm not talking about LAM enablement - I'm talking about adding a > > SPECTRE_V1_MITIGATION_LASS > > and setting that when X86_FEATURE_LASS is set so that luserspace gets told > that > > "Spectre V1 : Mitigation: LASS" > > or so. > > Makes more sense? I meant this crap, ofc: switch (bug) { case X86_BUG_CPU_MELTDOWN: if (boot_cpu_has(X86_FEATURE_PTI)) return sysfs_emit(buf, "Mitigation: PTI\n"); This should say "Mitigation: LASS" if LASS is enabled... Which begs the question: how do LASS and PTI interact now? -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette