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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-47fd45a0d7csm2395968f8f.35.2026.07.31.02.14.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 31 Jul 2026 02:14:26 -0700 (PDT) Date: Fri, 31 Jul 2026 10:14:25 +0100 From: David Laight To: Peter Zijlstra Cc: Borislav Petkov , Rik van Riel , Dave Hansen , Andy Lutomirski , Thomas Gleixner , Ingo Molnar , x86@kernel.org, linux-kernel@vger.kernel.org, kernel-team@meta.com Subject: Re: [PATCH] add tlbi=off to disable INVLPGB Message-ID: <20260731101425.3cdf139b@pumpkin> In-Reply-To: <20260731084656.GF776954@noisy.programming.kicks-ass.net> References: <20260729204341.3eb0b5ea@fangorn> <20260730014412.GEamqsbL46iteL25as@fat_crate.local> <20260730103227.GC751831@noisy.programming.kicks-ass.net> <20260730162318.GAamt6ds0siEVGwWlw@fat_crate.local> <20260730173104.GB776954@noisy.programming.kicks-ass.net> <20260730182439.GCamuW53V0HJHXNRqF@fat_crate.local> <20260731084656.GF776954@noisy.programming.kicks-ass.net> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Fri, 31 Jul 2026 10:46:56 +0200 Peter Zijlstra wrote: > On Thu, Jul 30, 2026 at 11:24:39AM -0700, Borislav Petkov wrote: > > On Thu, Jul 30, 2026 at 07:31:04PM +0200, Peter Zijlstra wrote: > > > But also, nah: > > > > > > https://support.arm.com/documentation/dui0802/b/A64-General-Instructions/TLBI > > > > > > "TLBI - TLB invalidate operation." > > > > Yap, that's what I meant. > > > > > tlbi={ipi,broadcast} > > > > > > Anyway, INVLPGB stands for INVaLidate PaGe Broadcast, ain'ted that hard > > > :-) Also, you know who to complain to for that instruction :-) > > > > Too late for that. :) > > > > "tlbi=broadcast" is a bit much to type: imagine you're hunched over some box > > in the server room, like Spiderman, crouching between racks and balancing the > > keyboard on some old pile of cables... :-P > > There is IPMI and other fancy remote management stuff these days. There > is no reason to suffer hearing loss for entering server rooms anymore > :-) The real problem is typing while wearing ski gloves... David > > > So how about shorter: > > > > "tlbi=bcast" > > "tlbi=ipi" > > > > ? > > > > We probably won't need to write "bcast" at all, actually, because that would > > be the default. So "tlbi=ipi" only. Yeah, that's good. > > Didn't we have a case where INVLPGB was disabled due to firmware or > something? I was thinking tlbi=broadcast could be used to force enable > it or something. > > Anyway, if that case don't exist, then yeah. >