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=-4.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 D0CEEC41604 for ; Tue, 6 Oct 2020 16:24:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7B5B0206D4 for ; Tue, 6 Oct 2020 16:24:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="O3SddyB+" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726123AbgJFQYP (ORCPT ); Tue, 6 Oct 2020 12:24:15 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:20860 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725925AbgJFQYP (ORCPT ); Tue, 6 Oct 2020 12:24:15 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1602001453; 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: in-reply-to:in-reply-to:references:references; bh=iTFHZeHpRZeGDIriRmYC9dE/HIjQlj5bWS/e7+7rp/E=; b=O3SddyB+A2VK5+zQpjKhvxDfYYugSf4oyoutjvTHT/RiT8qciFO/aSSPB0YKHP0/SQFz4G T6rADt0ip2xCbLHMA6Yy82fWeJe5H5NOIvLSJ9yV0Y4+/tI16wcLbqoPRpSx5Hv+sHmjCc na21JXbdc5sLJNflzs8Zo1FYacJHxKM= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-281-cMA5fL7OM1m8t7Ty_6lYIg-1; Tue, 06 Oct 2020 12:24:12 -0400 X-MC-Unique: cMA5fL7OM1m8t7Ty_6lYIg-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id E54C018829D5; Tue, 6 Oct 2020 16:24:10 +0000 (UTC) Received: from horse.redhat.com (ovpn-117-72.rdu2.redhat.com [10.10.117.72]) by smtp.corp.redhat.com (Postfix) with ESMTP id 5D2A61A835; Tue, 6 Oct 2020 16:24:07 +0000 (UTC) Received: by horse.redhat.com (Postfix, from userid 10451) id E76F5220AD7; Tue, 6 Oct 2020 12:24:06 -0400 (EDT) Date: Tue, 6 Oct 2020 12:24:06 -0400 From: Vivek Goyal To: Sean Christopherson Cc: Vitaly Kuznetsov , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, virtio-fs-list , pbonzini@redhat.com Subject: Re: [PATCH v4] kvm,x86: Exit to user space in case page fault error Message-ID: <20201006162406.GE5306@redhat.com> References: <20201002211314.GE24460@linux.intel.com> <20201005153318.GA4302@redhat.com> <20201005161620.GC11938@linux.intel.com> <20201006134629.GB5306@redhat.com> <877ds38n6r.fsf@vitty.brq.redhat.com> <20201006141501.GC5306@redhat.com> <874kn78l2z.fsf@vitty.brq.redhat.com> <20201006150817.GD5306@redhat.com> <871rib8ji1.fsf@vitty.brq.redhat.com> <20201006161200.GB17610@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201006161200.GB17610@linux.intel.com> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 06, 2020 at 09:12:00AM -0700, Sean Christopherson wrote: > On Tue, Oct 06, 2020 at 05:24:54PM +0200, Vitaly Kuznetsov wrote: > > Vivek Goyal writes: > > > So you will have to report token (along with -EFAULT) to user space. So this > > > is basically the 3rd proposal which is extension of kvm API and will > > > report say HVA/GFN also to user space along with -EFAULT. > > > > Right, I meant to say that guest kernel has full register state of the > > userspace process which caused APF to get queued and instead of trying > > to extract it in KVM and pass to userspace in case of a (later) failure > > we limit KVM api change to contain token or GFN only and somehow keep > > the rest in the guest. This should help with TDX/SEV-ES. > > Whatever gets reported to userspace should be identical with and without > async page faults, i.e. it definitely shouldn't have token information. > > Note, TDX doesn't allow injection exceptions, so reflecting a #PF back > into the guest is not an option. Nor do I think that's "correct" > behavior (see everyone's objections to using #PF for APF fixed). I.e. the > event should probably be an IRQ. I am not sure if IRQ for "Page not Present" works. Will it have some conflicts/issues with other high priority interrupts which can get injected before "Page not present". Vivek