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 X-Spam-Level: X-Spam-Status: No, score=-11.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 47AF3C43460 for ; Tue, 6 Apr 2021 13:49:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 18EC061241 for ; Tue, 6 Apr 2021 13:49:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344735AbhDFNt5 (ORCPT ); Tue, 6 Apr 2021 09:49:57 -0400 Received: from mail.kernel.org ([198.145.29.99]:35298 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232452AbhDFNty (ORCPT ); Tue, 6 Apr 2021 09:49:54 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id ABADD61241; Tue, 6 Apr 2021 13:49:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1617716986; bh=givtkE6w970XJqu87v0fdB35fYmge8p/pZlS2XlOWOQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ifTuBDBoh0Jwrue0jexOqECLiomd89qyNNgwZJRXFFUlGV6Sp6sRouovNUfPw/NS2 iaE9x7d7uivsvUF6dcEf0R/SIQ43DK/odMMI0Tq9i+OqRREcBIKi8w464+kRcnSMdk Rho+oltZ+ED54HrzL514jSzYanR170Xq0w/BtC5k9oH8EMXcFBzJSXHeHA+hW3aBxn qBM9H5oIdWbmprLJRMiDbx8uR5jMZqFVks4YVrFVyC7SgVvF1YV23gA6RF1lD1d+o8 7qGJx1yDJ0ghe4IOgm17qNc7NwvmObgpecDipY37uzbYLUyj9KFZmnNPZRr4TFGz1P KhRvYMqHq9FrA== Date: Tue, 6 Apr 2021 09:49:45 -0400 From: Sasha Levin To: Paolo Bonzini Cc: Greg Kroah-Hartman , linux-kernel@vger.kernel.org, stable@vger.kernel.org, Peter Feiner , Ben Gardon Subject: Re: [PATCH 5.10 096/126] KVM: x86/mmu: Use atomic ops to set SPTEs in TDP MMU map Message-ID: References: <20210405085031.040238881@linuxfoundation.org> <20210405085034.229578703@linuxfoundation.org> <98478382-23f8-57af-dc17-23c7d9899b9a@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <98478382-23f8-57af-dc17-23c7d9899b9a@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 06, 2021 at 08:09:26AM +0200, Paolo Bonzini wrote: >On 05/04/21 10:54, Greg Kroah-Hartman wrote: >>From: Ben Gardon >> >>[ Upstream commit 9a77daacc87dee9fd63e31243f21894132ed8407 ] >> >>To prepare for handling page faults in parallel, change the TDP MMU >>page fault handler to use atomic operations to set SPTEs so that changes >>are not lost if multiple threads attempt to modify the same SPTE. >> >>Reviewed-by: Peter Feiner >>Signed-off-by: Ben Gardon >> >Whoa no, you have included basically a whole new feature, except for >the final patch that actually enables the feature. The whole new MMU Right, we would usually grab dependencies rather than modifying the patch. It means we diverge less with upstream, and custom backports tend to be buggier than just grabbing dependencies. >is still not meant to be used in production and development is still >happening as of 5.13. Unrelated to this disucssion, but how are folks supposed to know which feature can and which feature can't be used in production? If it's a released kernel, in theory anyone can pick up 5.12 and use it in production. >Were all these patches (82-97) included just to enable patch 98 ("KVM: >x86/mmu: Ensure TLBs are flushed for TDP MMU during NX zapping")? >Same for 105-120 in 5.11. Yup. Is there anything wrong with those patches? -- Thanks, Sasha