Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [RFC v3 0/2] kvm "fake DAX" device flushing
To:     Pankaj Gupta <pagupta@redhat.com>, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org, qemu-devel@nongnu.org,
        linux-nvdimm@ml01.01.org
Cc:     jack@suse.cz, stefanha@redhat.com, dan.j.williams@intel.com,
        riel@surriel.com, haozhong.zhang@intel.com, nilal@redhat.com,
        kwolf@redhat.com, pbonzini@redhat.com, ross.zwisler@intel.com,
        xiaoguangrong.eric@gmail.com, hch@infradead.org, mst@redhat.com,
        niteshnarayanlal@hotmail.com, lcapitulino@redhat.com,
        imammedo@redhat.com, eblake@redhat.com
References: <20180713075232.9575-1-pagupta@redhat.com>
From:   David Hildenbrand <david@redhat.com>
Openpgp: preference=signencrypt
Autocrypt: addr=david@redhat.com; prefer-encrypt=mutual; keydata=
 xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ
 dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL
 QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp
 XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK
 Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9
 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt
 WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc
 UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv
 jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb
 B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk
 ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwX4EEwECACgFAljj9eoCGwMFCQlmAYAGCwkI
 BwMCBhUIAgkKCwQWAgMBAh4BAheAAAoJEE3eEPcA/4Na5IIP/3T/FIQMxIfNzZshIq687qgG
 8UbspuE/YSUDdv7r5szYTK6KPTlqN8NAcSfheywbuYD9A4ZeSBWD3/NAVUdrCaRP2IvFyELj
 xoMvfJccbq45BxzgEspg/bVahNbyuBpLBVjVWwRtFCUEXkyazksSv8pdTMAs9IucChvFmmq3
 jJ2vlaz9lYt/lxN246fIVceckPMiUveimngvXZw21VOAhfQ+/sofXF8JCFv2mFcBDoa7eYob
 s0FLpmqFaeNRHAlzMWgSsP80qx5nWWEvRLdKWi533N2vC/EyunN3HcBwVrXH4hxRBMco3jvM
 m8VKLKao9wKj82qSivUnkPIwsAGNPdFoPbgghCQiBjBe6A75Z2xHFrzo7t1jg7nQfIyNC7ez
 MZBJ59sqA9EDMEJPlLNIeJmqslXPjmMFnE7Mby/+335WJYDulsRybN+W5rLT5aMvhC6x6POK
 z55fMNKrMASCzBJum2Fwjf/VnuGRYkhKCqqZ8gJ3OvmR50tInDV2jZ1DQgc3i550T5JDpToh
 dPBxZocIhzg+MBSRDXcJmHOx/7nQm3iQ6iLuwmXsRC6f5FbFefk9EjuTKcLMvBsEx+2DEx0E
 UnmJ4hVg7u1PQ+2Oy+Lh/opK/BDiqlQ8Pz2jiXv5xkECvr/3Sv59hlOCZMOaiLTTjtOIU7Tq
 7ut6OL64oAq+zsFNBFXLn5EBEADn1959INH2cwYJv0tsxf5MUCghCj/CA/lc/LMthqQ773ga
 uB9mN+F1rE9cyyXb6jyOGn+GUjMbnq1o121Vm0+neKHUCBtHyseBfDXHA6m4B3mUTWo13nid
 0e4AM71r0DS8+KYh6zvweLX/LL5kQS9GQeT+QNroXcC1NzWbitts6TZ+IrPOwT1hfB4WNC+X
 2n4AzDqp3+ILiVST2DT4VBc11Gz6jijpC/KI5Al8ZDhRwG47LUiuQmt3yqrmN63V9wzaPhC+
 xbwIsNZlLUvuRnmBPkTJwwrFRZvwu5GPHNndBjVpAfaSTOfppyKBTccu2AXJXWAE1Xjh6GOC
 8mlFjZwLxWFqdPHR1n2aPVgoiTLk34LR/bXO+e0GpzFXT7enwyvFFFyAS0Nk1q/7EChPcbRb
 hJqEBpRNZemxmg55zC3GLvgLKd5A09MOM2BrMea+l0FUR+PuTenh2YmnmLRTro6eZ/qYwWkC
 u8FFIw4pT0OUDMyLgi+GI1aMpVogTZJ70FgV0pUAlpmrzk/bLbRkF3TwgucpyPtcpmQtTkWS
 gDS50QG9DR/1As3LLLcNkwJBZzBG6PWbvcOyrwMQUF1nl4SSPV0LLH63+BrrHasfJzxKXzqg
 rW28CTAE2x8qi7e/6M/+XXhrsMYG+uaViM7n2je3qKe7ofum3s4vq7oFCPsOgwARAQABwsFl
 BBgBAgAPBQJVy5+RAhsMBQkJZgGAAAoJEE3eEPcA/4NagOsP/jPoIBb/iXVbM+fmSHOjEshl
 KMwEl/m5iLj3iHnHPVLBUWrXPdS7iQijJA/VLxjnFknhaS60hkUNWexDMxVVP/6lbOrs4bDZ
 NEWDMktAeqJaFtxackPszlcpRVkAs6Msn9tu8hlvB517pyUgvuD7ZS9gGOMmYwFQDyytpepo
 YApVV00P0u3AaE0Cj/o71STqGJKZxcVhPaZ+LR+UCBZOyKfEyq+ZN311VpOJZ1IvTExf+S/5
 lqnciDtbO3I4Wq0ArLX1gs1q1XlXLaVaA3yVqeC8E7kOchDNinD3hJS4OX0e1gdsx/e6COvy
 qNg5aL5n0Kl4fcVqM0LdIhsubVs4eiNCa5XMSYpXmVi3HAuFyg9dN+x8thSwI836FoMASwOl
 C7tHsTjnSGufB+D7F7ZBT61BffNBBIm1KdMxcxqLUVXpBQHHlGkbwI+3Ye+nE6HmZH7IwLwV
 W+Ajl7oYF+jeKaH4DZFtgLYGLtZ1LDwKPjX7VAsa4Yx7S5+EBAaZGxK510MjIx6SGrZWBrrV
 TEvdV00F2MnQoeXKzD7O4WFbL55hhyGgfWTHwZ457iN9SgYi1JLPqWkZB0JRXIEtjd4JEQcx
 +8Umfre0Xt4713VxMygW0PnQt5aSQdMD58jHFxTk092mU+yIHj5LeYgvwSgZN4airXk5yRXl
 SE+xAvmumFBY
Organization: Red Hat GmbH
Message-ID: <1328e543-0276-8f33-1744-8baa053023c4@redhat.com>
Date:   Tue, 28 Aug 2018 14:13:24 +0200
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101
 Thunderbird/52.9.1
MIME-Version: 1.0
In-Reply-To: <20180713075232.9575-1-pagupta@redhat.com>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 13.07.2018 09:52, Pankaj Gupta wrote:
> This is RFC V3 for 'fake DAX' flushing interface sharing
> for review. This patchset has two parts:
> 
> - Guest virtio-pmem driver
>   Guest driver reads persistent memory range from paravirt device 
>   and registers with 'nvdimm_bus'. 'nvdimm/pmem' driver uses this 
>   information to allocate persistent memory range. Also, we have 
>   implemented guest side of VIRTIO flushing interface.
> 
> - Qemu virtio-pmem device
>   It exposes a persistent memory range to KVM guest which at host 
>   side is file backed memory and works as persistent memory device. 
>   In addition to this it provides virtio device handling of flushing 
>   interface. KVM guest performs Qemu side asynchronous sync using 
>   this interface.
> 
> Changes from RFC v2:
> - Add flush function in the nd_region in place of switching
>   on a flag - Dan & Stefan
> - Add flush completion function with proper locking and wait
>   for host side flush completion - Stefan & Dan
> - Keep userspace API in uapi header file - Stefan, MST
> - Use LE fields & New device id - MST
> - Indentation & spacing suggestions - MST & Eric
> - Remove extra header files & add licensing - Stefan
> 
> Changes from RFC v1:
> - Reuse existing 'pmem' code for registering persistent 
>   memory and other operations instead of creating an entirely 
>   new block driver.
> - Use VIRTIO driver to register memory information with 
>   nvdimm_bus and create region_type accordingly. 
> - Call VIRTIO flush from existing pmem driver.
> 
> Details of project idea for 'fake DAX' flushing interface is 
> shared [2] & [3].
> 
> Pankaj Gupta (2):
>    Add virtio-pmem guest driver
>    pmem: device flush over VIRTIO
> 
> [1] https://marc.info/?l=linux-mm&m=150782346802290&w=2
> [2] https://www.spinics.net/lists/kvm/msg149761.html
> [3] https://www.spinics.net/lists/kvm/msg153095.html  
> 
>  drivers/nvdimm/nd.h              |    1 
>  drivers/nvdimm/pmem.c            |    4 
>  drivers/nvdimm/region_devs.c     |   24 +++-
>  drivers/virtio/Kconfig           |    9 +
>  drivers/virtio/Makefile          |    1 
>  drivers/virtio/virtio_pmem.c     |  190 +++++++++++++++++++++++++++++++++++++++
>  include/linux/libnvdimm.h        |    5 -
>  include/linux/virtio_pmem.h      |   44 +++++++++
>  include/uapi/linux/virtio_ids.h  |    1 
>  include/uapi/linux/virtio_pmem.h |   40 ++++++++
>  10 files changed, 310 insertions(+), 9 deletions(-)
> 

Hi Pankaj,

do you have a branch for the QEMU part somewhere available? I want to
see how this works with MemoryDevice changes.

-- 

Thanks,

David / dhildenb