From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 9504FC7EE29 for ; Fri, 9 Jun 2023 07:44:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Subject:Cc:To:From:Message-ID:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=KHbG3tVejpypjitiPyxUjU8vYgu4ODhneZRti6oHfHY=; b=ErIvEnZWTFQxgT +SOCGnGi3HAlKY9tb2v9D1A+Z+0KSbGjMjlq9T9caNbzj3YUDq3hbKSJqc+qxwGPleZpJlxZbFjjQ faodb3cipYgaNkRWcX7zgQH0NreNzV1+LdgA5KznZuH8IwnlHVZIaZn3sopH+OlvM5RHNMUARQEw1 LdlPz2whcMJrCvDnInxI07/+Hkv6Ziq4SNxJKYHiyMFNzT+3ObnPB83y2QNXDXrpDJZLkkwv+1xlD Y6XZ+287rl19oOh5qHZSWPBo4Bqw211BB4a7GdbvGLkju6C6de8cBLvpQuVMJMr66cycJ9oIU+B0y CjaOqVorP4Va7hMybI1w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1q7Wn9-00C5Mn-1z; Fri, 09 Jun 2023 07:44:15 +0000 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1q7Wn7-00C5MN-0m for linux-arm-kernel@lists.infradead.org; Fri, 09 Jun 2023 07:44:14 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 93FD164C48; Fri, 9 Jun 2023 07:44:12 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EF07FC433D2; Fri, 9 Jun 2023 07:44:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1686296652; bh=9W3yv9+UNkGc7TPUGVsDpkL0Oq0BCL1BMC/LGHkAQrI=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=GWJjBNaxOl0nAfFeFajFeE+8px32MH9qlNYNJPa9GWHTP1w7IYEPDyyKS3sfc2kV1 f7OQFMjKASqcumwyhqvPNb+C8ByDmpWYZFMmZK8TGf7dr6EfX3uEd124xIbNuXkiJI G2h01u18NoVzmi74HN/UroV95kF4izIuboveyPdrPFAACilc530XHZC75LaBfkX2Fn s3lPY38SZWNv3MVexW7Szg6amonZxi9zZCHZPcNEU9jDCIqK+/KbpNs73Jz67+9N5v LsijJM77KHf0Ou5eTNEobtv8iO5WnjnthBOrTCMoNo77acDil0Dab5jWyyHDpkECGz FOiFwh75T8Iig== Received: from 152.5.30.93.rev.sfr.net ([93.30.5.152] helo=wait-a-minute.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1q7Wn3-0040E7-Je; Fri, 09 Jun 2023 08:44:09 +0100 Date: Fri, 09 Jun 2023 08:44:07 +0100 Message-ID: <878rctnkqg.wl-maz@kernel.org> From: Marc Zyngier To: Chun-Tse Shao Cc: linux-kernel@vger.kernel.org, yuzhao@google.com, oliver.upton@linux.dev, James Morse , Suzuki K Poulose , Zenghui Yu , Catalin Marinas , Will Deacon , Ben Gardon , Gavin Shan , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev Subject: Re: [PATCH v1 3/3] KVM: arm64: Using rcu_read_lock() for kvm_pgtable_stage2_mkyoung() In-Reply-To: <20230608220558.39094-4-ctshao@google.com> References: <20230608220558.39094-1-ctshao@google.com> <20230608220558.39094-4-ctshao@google.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/28.2 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") X-SA-Exim-Connect-IP: 93.30.5.152 X-SA-Exim-Rcpt-To: ctshao@google.com, linux-kernel@vger.kernel.org, yuzhao@google.com, oliver.upton@linux.dev, james.morse@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, catalin.marinas@arm.com, will@kernel.org, bgardon@google.com, gshan@redhat.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230609_004413_323973_FCC01158 X-CRM114-Status: GOOD ( 15.05 ) 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, 08 Jun 2023 23:05:41 +0100, Chun-Tse Shao wrote: > > Access bit is RCU safe and can be set without taking kvm->mmu_lock(). Please explain why. What happens when the page tables are *not* RCU controlled, such as in the pKVM case? > Replacing existing kvm->mmu_lock() with rcu_read_lock() for better > performance. Please define "better performance", quote workloads, figures, HW setup and point to a reproducer. Please add a cover letter to your patch series explaining the context this happens in. Also, I'm getting increasingly annoyed by the lack of coordination between seamingly overlapping patch series (this, Yu's, Anish's and Vipin's), all from a single company. Surely you can talk to each other and devise a coordinated approach? Thanks, M. -- Without deviation from the norm, progress is not possible. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel