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Thu, 07 Mar 2024 15:22:02 -0800 (PST) MIME-Version: 1.0 References: <20240307133916.3782068-1-yosryahmed@google.com> <20240307133916.3782068-2-yosryahmed@google.com> In-Reply-To: From: Yosry Ahmed Date: Thu, 7 Mar 2024 15:21:26 -0800 Message-ID: Subject: Re: [RFC PATCH 1/3] x86/mm: fix LAM cr3 mask inconsistency during context switch To: Dave Hansen Cc: Andrew Morton , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Peter Zijlstra , Andy Lutomirski , "Kirill A. Shutemov" , x86@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: 05AFE140013 X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: 3884bpftb6fcgdkhqxkx5y48s1iacwdj X-HE-Tag: 1709853723-359370 X-HE-Meta: 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 cEmmsLBh w7XFRZWktp1lso1RMRPGhMUlvrNMmaTVmPef5zaKQXEVVEz+DNKwiUnqldQtezYGcOgMiOz4EvikKAbkNlwrWmYMEhmxqatE+cZ8Xz9pXVzS1qhJnriQeSYH8GR34+0njK0fJmdoyM/CIscIaWPtPTqO1wZLrdz5XHCkEURv4xi5wKnpkomYmL1OVMX/iWKgfby0XUPO/Y08rMeHcI8KTum00vw== 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: > > The "set_" naming bugs me in both of the sites that get modified here. > > I'd be with a new name that fits better, if we can think of one. > > Is it because it's not clear we are updating cpu_tlbstate (in which case > I think update_cpu_tlbstate_lam() is an improvement), or is it because > the function returns a value now? If the latter we can put "return" in > the name somewhere, or keep the function void and pass in an output > parameter. Or we can avoid returning a value from the helper and avoid passing an mm. The callers would be more verbose, they'll have to call mm_lam_cr3_mask() and mm_untag_mask() and pass the results into the helper (set_tlbstate_lam_mode() or update_cpu_tlbstate_lam()). Another advantage of this is that we can move the READ_ONCE to switch_mm_irqs_off() and keep the comment here. WDYT?