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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CE16BC7EE23 for ; Thu, 1 Jun 2023 22:43:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231600AbjFAWnf (ORCPT ); Thu, 1 Jun 2023 18:43:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51418 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229524AbjFAWnd (ORCPT ); Thu, 1 Jun 2023 18:43:33 -0400 Received: from out-18.mta0.migadu.com (out-18.mta0.migadu.com [91.218.175.18]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 76D9A136 for ; Thu, 1 Jun 2023 15:43:31 -0700 (PDT) Date: Thu, 1 Jun 2023 22:43:24 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1685659409; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=OwwcO93XUsSL6ykN5XfObGDM2dVn0PA2p876+g1yYcU=; b=K2WfBTvSAHfrUiKalALQGQq2zayiZCV9KlBLhF4Krhjs82D/jAE3o9JTggvR2fvpxbqIq3 NQnh6Hu5F7XLykhAGbO5ynhU5yErAcvseO1npOikikhhj4kqPakjdnTqiphYCT7mVbu57A CHD07ERWGhSRfFVZKVuSj34pCzcY0cE= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Oliver Upton To: Anish Moorthy Cc: Sean Christopherson , David Matlack , pbonzini@redhat.com, maz@kernel.org, jthoughton@google.com, bgardon@google.com, ricarkol@google.com, axelrasmussen@google.com, peterx@redhat.com, kvm@vger.kernel.org, kvmarm@lists.linux.dev Subject: Re: [PATCH v3 00/22] Improve scalability of KVM + userfaultfd live migration via annotated memory faults. Message-ID: References: <20230412213510.1220557-1-amoorthy@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Tue, May 23, 2023 at 10:49:04AM -0700, Anish Moorthy wrote: > On Wed, May 10, 2023 at 4:44 PM Anish Moorthy wrote: > > > > On Wed, May 10, 2023 at 3:35 PM Sean Christopherson wrote: > > > > > > Yeah, when I speed read the series, several of the conversions stood out as being > > > "wrong". My (potentially unstated) idea was that KVM would only signal > > > KVM_EXIT_MEMORY_FAULT when the -EFAULT could be traced back to a user access, > > > i.e. when the fault _might_ be resolvable by userspace. > > > > Sean, besides direct_map which other patches did you notice as needing > > to be dropped/marked as unrecoverable errors? > > I tried going through on my own to try and identify the incorrect > annotations: here's my read. > > Correct (or can easily be corrected) > ----------------------------------------------- > - user_mem_abort > Incorrect as is: the annotations in patch 19 are incorrect, as they > cover an error-on-no-slot case and one more I don't fully understand: That other case is a wart we endearingly refer to as MTE (Memory Tagging Extension). You theoretically _could_ pop out an annotated exit here, as userspace likely messed up the mapping (like PROT_MTE missing). But I'm perfectly happy letting someone complain about it before we go out of our way to annotate that one. So feel free to drop. -- Thanks, Oliver