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=-0.8 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 D5757C28CF8 for ; Sat, 13 Oct 2018 16:10:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 906AD20835 for ; Sat, 13 Oct 2018 16:10:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=intel-com.20150623.gappssmtp.com header.i=@intel-com.20150623.gappssmtp.com header.b="YOL18WEI" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 906AD20835 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726831AbeJMXsI (ORCPT ); Sat, 13 Oct 2018 19:48:08 -0400 Received: from mail-ot1-f66.google.com ([209.85.210.66]:38875 "EHLO mail-ot1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726417AbeJMXsI (ORCPT ); Sat, 13 Oct 2018 19:48:08 -0400 Received: by mail-ot1-f66.google.com with SMTP id l1so15139657otj.5 for ; Sat, 13 Oct 2018 09:10:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=intel-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=1rUm75vsj2T3ZwwUEwJjSXUa/a61Y8S155/Y4IOfsEg=; b=YOL18WEIzI48IFjuX+LN0oYP7r/rIK24Le2MOrDJQNVTY6KWL2bKLs1kcSnUdyC9mw kfv/zSqV9CoSK2O32AxY53OdqQPLPOe0sGtqzBCCtkZ9/CU+pYbpCIM4k+pNp2A4TDPX C/4LjmjsVdhZCXHy+eTASqsKyKKZBB7zjS3xU8kd/n8dG3kK64D4L65HYxuqw1rY/6RA OV8Xw1mo9LAIFPQIhgifOGxs8mzC3jL4IfAHC4MXs0/kqT3vyZzAhrqaaFocUs+In0dy 9hZI4C0v0r6LNMFV1uRf5SZ2Pa+oi1lNQPyOyqD8iOyJSip+t+8YFd0lSb4XKvfh6H3I QVkQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=1rUm75vsj2T3ZwwUEwJjSXUa/a61Y8S155/Y4IOfsEg=; b=jSkt0po3ZiZByVLU89Y1tqNl6RUZuYhA38qF/9J9mLfqIh6AZb/HasBgNVm8oGr0+4 QMzkdpCxNwxTJUm3Ho37x2mONz8hkPNIW51nKc7CseE9v5Vx8njWEM7O1U8OBP5xpHcA 3cFvVbcbpgI7qmCwO6/2Zf+d0NiErxBO/Aj9VmEFeeBLCE2YefrCwT6V+R+i6ZxeOFgV LdUq4Pa9dKKfO0AupS+b5ro/UAKLksQ0tYJeYWh0mrOYxoUTtUf77Cs0K7MoqMv2gt2r KmSgS5oF6GYl9WfEujyt1VQUdGaiZhRkbbfJ8rnms/+N+UDWlxT1B1mL7XhnZ0cErVon HzDA== X-Gm-Message-State: ABuFfoiFcBKcytRIPMATnx3T0yBpqivHkMhvf7rHzje0TxX5iDuHVQrr amHOVHILquah4DS0Zom/WqNAS611uUmZVmnDHRwEVw== X-Google-Smtp-Source: ACcGV61o1EUMByc7H2Mz/Fv5yQKaM5cGIb8m9ocoFDu9s/YrqsrX8V2agWnvH72oUz/bwtZTx7n3C31nMT5J2BWPbF0= X-Received: by 2002:a9d:256e:: with SMTP id j43mr6779840otd.367.1539447024538; Sat, 13 Oct 2018 09:10:24 -0700 (PDT) MIME-Version: 1.0 References: <20181013050021.11962-1-pagupta@redhat.com> <20181013050021.11962-3-pagupta@redhat.com> In-Reply-To: <20181013050021.11962-3-pagupta@redhat.com> From: Dan Williams Date: Sat, 13 Oct 2018 09:10:13 -0700 Message-ID: Subject: Re: [PATCH v2 2/2] virtio-pmem: Add virtio pmem driver To: Pankaj Gupta Cc: Linux Kernel Mailing List , KVM list , Qemu Developers , linux-nvdimm , Jan Kara , Stefan Hajnoczi , Rik van Riel , Nitesh Narayan Lal , Kevin Wolf , Paolo Bonzini , zwisler@kernel.org, Vishal L Verma , Dave Jiang , David Hildenbrand , Xiao Guangrong , Christoph Hellwig , "Michael S. Tsirkin" , lcapitulino@redhat.com, Igor Mammedov , Eric Blake Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 12, 2018 at 10:01 PM Pankaj Gupta wrote: > > This patch adds virtio-pmem driver for KVM guest. > > Guest reads the persistent memory range information from > Qemu over VIRTIO and registers it on nvdimm_bus. It also > creates a nd_region object with the persistent memory > range information so that existing 'nvdimm/pmem' driver > can reserve this into system memory map. This way > 'virtio-pmem' driver uses existing functionality of pmem > driver to register persistent memory compatible for DAX > capable filesystems. > > This also provides function to perform guest flush over > VIRTIO from 'pmem' driver when userspace performs flush > on DAX memory range. Before we can move forward with this driver we need additional filesystem enabling to detect when the backing device is fronting DAX pmem or a paravirtualized page cache through virtio-pmem. Any interface that requires fsync() and a round trip to the hypervisor to flush host page cache is not DAX.