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=-6.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,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 E812CC54E49 for ; Thu, 7 May 2020 21:24:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C4EAA20575 for ; Thu, 7 May 2020 21:24:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="hO1xxG7l" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726750AbgEGVYv (ORCPT ); Thu, 7 May 2020 17:24:51 -0400 Received: from us-smtp-2.mimecast.com ([205.139.110.61]:32859 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726464AbgEGVYu (ORCPT ); Thu, 7 May 2020 17:24:50 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1588886688; 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=+hf8+llPyWbESgzeV9oWGjfToVmGFDxL774OpBs4NOI=; b=hO1xxG7lElaKlNqw8JW+pem8vY1uJBJgtDGUMvJaiS7my9qdTwksfRHeDci3JHfOI5/Hcp SidvvUrlI6aM1HkkXiiIa4JIwhqUhn+137iw+PqLBFx+ryerXtmWJkNTsOQPvHS5BWGYwD SG6nL73t4dEM1kNDe5jWDvygzaGhA1o= Received: from mail-qv1-f70.google.com (mail-qv1-f70.google.com [209.85.219.70]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-366-bWBs8ER0N823d3efUQZpJQ-1; Thu, 07 May 2020 17:24:47 -0400 X-MC-Unique: bWBs8ER0N823d3efUQZpJQ-1 Received: by mail-qv1-f70.google.com with SMTP id bm3so7272144qvb.0 for ; Thu, 07 May 2020 14:24:47 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=+hf8+llPyWbESgzeV9oWGjfToVmGFDxL774OpBs4NOI=; b=GLk+6xACbzD/4u8nKEN/Qy0tSHo1vZCsMDE+Yt+DYyix+qQIsGbgj/DPTKY6+/sqwu bnT3L+DHDCqQ6jseU5rew7kZ18/Rkoz6KUvO7S47qAtpH5KOnLz6/KGKm4yX2caDvVTj JcgyySzR9U6wAsS6FOhuBq7jY7spwCUFjS9S/U5FcxJkCRITrrojWEoRvnmgf8pJ0T4i w0Z3Z6fl2KuUv71ibJwSv3z5rc8GOSaxNbfaF0lSvyG9D+jiyA4XuWjTb+bdmRum8UTH PUoYIC2590NrTCiq/YDs2kbxY9f9vyQpikHkctYfLqcaEOHTXeQMxUOzDr+i91pk4I85 WT9g== X-Gm-Message-State: AGi0PubYmYYmXQ0nqNiNo6DU0V/EV6hWSTYPuH7w1+Ekq2UTfqLZY6Jc D9ocDty7e10nqrlUYM5m2CajPszs0uSzE+2rcd5BPpGl5z1YyTEp2Ki/c9i/Tvg92PlQ/q0gv+5 Lz0uOiw1fmSSoMHZvrk4yxTPp X-Received: by 2002:a05:6214:287:: with SMTP id l7mr15289602qvv.38.1588886686036; Thu, 07 May 2020 14:24:46 -0700 (PDT) X-Google-Smtp-Source: APiQypIYk2Q7XtkMJpVDHjFh9SbqkSsjahcyPlqUXryygjPQkw6M3+HDsdemXyYJU+pQXbjJup5B6w== X-Received: by 2002:a05:6214:287:: with SMTP id l7mr15289582qvv.38.1588886685719; Thu, 07 May 2020 14:24:45 -0700 (PDT) Received: from xz-x1 ([2607:9880:19c0:32::2]) by smtp.gmail.com with ESMTPSA id l2sm5231724qkd.57.2020.05.07.14.24.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 07 May 2020 14:24:44 -0700 (PDT) Date: Thu, 7 May 2020 17:24:43 -0400 From: Peter Xu To: Alex Williamson Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, cohuck@redhat.com, jgg@ziepe.ca Subject: Re: [PATCH v2 1/3] vfio/type1: Support faulting PFNMAP vmas Message-ID: <20200507212443.GO228260@xz-x1> References: <158871401328.15589.17598154478222071285.stgit@gimli.home> <158871568480.15589.17339878308143043906.stgit@gimli.home> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <158871568480.15589.17339878308143043906.stgit@gimli.home> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 05, 2020 at 03:54:44PM -0600, Alex Williamson wrote: > With conversion to follow_pfn(), DMA mapping a PFNMAP range depends on > the range being faulted into the vma. Add support to manually provide > that, in the same way as done on KVM with hva_to_pfn_remapped(). > > Signed-off-by: Alex Williamson > --- > drivers/vfio/vfio_iommu_type1.c | 36 +++++++++++++++++++++++++++++++++--- > 1 file changed, 33 insertions(+), 3 deletions(-) > > diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c > index cc1d64765ce7..4a4cb7cd86b2 100644 > --- a/drivers/vfio/vfio_iommu_type1.c > +++ b/drivers/vfio/vfio_iommu_type1.c > @@ -317,6 +317,32 @@ static int put_pfn(unsigned long pfn, int prot) > return 0; > } > > +static int follow_fault_pfn(struct vm_area_struct *vma, struct mm_struct *mm, > + unsigned long vaddr, unsigned long *pfn, > + bool write_fault) > +{ > + int ret; > + > + ret = follow_pfn(vma, vaddr, pfn); > + if (ret) { > + bool unlocked = false; > + > + ret = fixup_user_fault(NULL, mm, vaddr, > + FAULT_FLAG_REMOTE | > + (write_fault ? FAULT_FLAG_WRITE : 0), > + &unlocked); > + if (unlocked) > + return -EAGAIN; Hi, Alex, IIUC this retry is not needed too because fixup_user_fault() will guarantee the fault-in is done correctly with the valid PTE as long as ret==0, even if unlocked==true. Note: there's another patch just removed the similar retry in kvm: https://lore.kernel.org/kvm/20200416155906.267462-1-peterx@redhat.com/ Thanks, > + > + if (ret) > + return ret; > + > + ret = follow_pfn(vma, vaddr, pfn); > + } > + > + return ret; > +} -- Peter Xu