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Sat, 03 Oct 2026 16:09:42 +0000 Date: Sat, 03 Oct 2026 17:12:50 +0100 Message-ID: <87mrsu3gql.wl-maz@kernel.org> From: Marc Zyngier To: Kristina =?UTF-8?B?TWFydMWhZW5rbw==?= Cc: linux-arm-kernel@lists.infradead.org, linux-acpi@vger.kernel.org, kvmarm@lists.linux.dev, linux-efi@vger.kernel.org, Catalin Marinas , Will Deacon , Mark Rutland , Ryan Roberts , David Hildenbrand , Lorenzo Stoakes , Linu Cherian , Anshuman Khandual , Lorenzo Pieralisi , Hanjun Guo , Sudeep Holla , Oliver Upton , Fuad Tabba , Joey Gouly , Steffen Eiden , Suzuki K Poulose , Zenghui Yu , Ard Biesheuvel , Ilias Apalodimas Subject: Re: [RFC 00/12] arm64: Add support for TLBI domains In-Reply-To: <20261001110655.461473-1-kristina.martsenko@arm.com> References: <20261001110655.461473-1-kristina.martsenko@arm.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/30.1 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: kristina.martsenko@arm.com, linux-arm-kernel@lists.infradead.org, linux-acpi@vger.kernel.org, kvmarm@lists.linux.dev, linux-efi@vger.kernel.org, catalin.marinas@arm.com, will@kernel.org, mark.rutland@arm.com, ryan.roberts@arm.com, david@kernel.org, ljs@kernel.org, linu.cherian@arm.com, anshuman.khandual@arm.com, lpieralisi@kernel.org, guohanjun@huawei.com, sudeep.holla@kernel.org, oupton@kernel.org, fuad.tabba@linux.dev, joey.gouly@arm.com, seiden@linux.ibm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, ardb@kernel.org, ilias.apalodimas@linaro.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Kristina, On Thu, 01 Oct 2026 12:06:43 +0100, Kristina Mart=C5=A1enko wrote: [...] > * It's also possible to use TLBI domains to limit a KVM guest's TLB > invalidations to CPUs where the guest has run. I'll try to include th= at in > the next version. This series only disables domains for guests. My take on this is that just like MPAM, it makes little sense to expose this to guests. As long as the L0 hypervisor has the means that to scope TLBIs to the relevant domains (subset of CPUs to start with, but hopefully SMMUs eventually), we're good. > * With this series a long-running process may eventually run on all CPU= s and > just issue broadcast TLBIs. It may be worth periodically reducing the= set > of CPUs but it's not clear when. I had a think about that some time ago, and thought that you were sure to be sub-optimal when the number of CPUs you have run on is greater than the number of threads in your process. But I'm sure there are better heuristics! ;-) Thanks, M. --=20 Jazz isn't dead. It just smells funny.