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bh=2AR3jHJ/sExRco1cYv+OP7+KalJq3WrRTcrLTTSrVjQ=; b=ZU4ZoumYZrWfLri6WoUYdJwdT3Z28ZwKW8/JHnU32NcDh+xHlO8SKT9xCrnxV760HE5MdC hmgfk7/+AQIedNSFFxjRAF+WQnmvzVXuFqlL8AiOZM5fu3O3xUVwjgUUfE4QHrOhYlBXV6 SGMdNeJlKTeKHBtYKlJfv3mB0cx+yOE= 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-500-uRQfMTCgPJGjdv59EW6uVw-1; Wed, 28 Apr 2021 01:55:55 -0400 X-MC-Unique: uRQfMTCgPJGjdv59EW6uVw-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id E01E3803622; Wed, 28 Apr 2021 05:55:54 +0000 (UTC) Received: from wangxiaodeMacBook-Air.local (ovpn-13-59.pek2.redhat.com [10.72.13.59]) by smtp.corp.redhat.com (Postfix) with ESMTP id 945E560CC6; Wed, 28 Apr 2021 05:55:48 +0000 (UTC) Subject: Re: [PATCH RFC 0/1] To add HMP interface to dump PCI MSI-X table/PBA To: Dongli Zhang , "Dr. David Alan Gilbert" References: <20210423044713.3403-1-dongli.zhang@oracle.com> <25113515-5c1d-c557-d0cc-04bfacecb6ee@redhat.com> <8aad1273-5c17-a2d7-46cd-eb149c6c57b8@oracle.com> <37e7aa41-5c87-3276-67f6-b5bd64dde7ea@redhat.com> <3e4cfcf2-c4b9-028a-4d06-22b1e9a23455@oracle.com> From: Jason Wang Message-ID: <279945e6-4bd0-2157-1973-6e44ce97b359@redhat.com> Date: Wed, 28 Apr 2021 13:55:47 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.10.0 MIME-Version: 1.0 In-Reply-To: <3e4cfcf2-c4b9-028a-4d06-22b1e9a23455@oracle.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=jasowang@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Received-SPF: pass client-ip=170.10.133.124; envelope-from=jasowang@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -29 X-Spam_score: -3.0 X-Spam_bar: --- X-Spam_report: (-3.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.218, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: berrange@redhat.com, ehabkost@redhat.com, mst@redhat.com, joe.jin@oracle.com, qemu-devel@nongnu.org, pbonzini@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" 在 2021/4/28 下午1:10, Dongli Zhang 写道: > Hi Jason, > > On 4/27/21 7:31 PM, Jason Wang wrote: >> 在 2021/4/27 下午4:53, Dr. David Alan Gilbert 写道: >>> * Dongli Zhang (dongli.zhang@oracle.com) wrote: >>>> On 4/22/21 11:01 PM, Jason Wang wrote: >>>>> 在 2021/4/23 下午12:47, Dongli Zhang 写道: >>>>>> This is inspired by the discussion with Jason on below patchset. >>>>>> >>>>>> https://urldefense.com/v3/__https://lists.gnu.org/archive/html/qemu-devel/2021-03/msg09020.html__;!!GqivPVa7Brio!KbGQZW5lq3JZ60k12NuWZ6Th1lT6AwmBTF0pBgoWUKKQ4-2UhdW57PtvXUN5XQnZ2NU$ >>>>>> >>>>>> >>>>>> The new HMP command is introduced to dump the MSI-X table and PBA. >>>>>> >>>>>> Initially, I was going to add new option to "info pci". However, as the >>>>>> number of entries is not determined and the output of MSI-X table is much >>>>>> more similar to the output of hmp_info_tlb()/hmp_info_mem(), this patch >>>>>> adds interface for only HMP. >>>>>> >>>>>> The patch is tagged with RFC because I am looking for suggestions on: >>>>>> >>>>>> 1. Is it fine to add new "info msix " command? >>>>> I wonder the reason for not simply reusing "info pci"? >>>> The "info pci" will show PCI data for all devices and it does not accept any >>>> argument to print for a specific device. >>>> >>>> In addition, the "info pci" relies on qmp_query_pci(), where this patch will not >>>> implement the interface for QMP considering the number of MSI-X entries is not >>>> determined. >>>> >>>> Suppose we have 10 NVMe (emulated by QEMU with default number of queues), we >>>> will have about 600+ lines of output. >>>  From an HMP perspective I'm happy, so: >>> >>> Acked-by: Dr. David Alan Gilbert >>> >>> but since I don't know much about MSI I'd like to see Jason's reply. >> >> I think we'd better have more information, e.g the device can optionally report >> how the MSI-X vector is used. >> >> Virtio-pci could be the first user for this. > As discussed in another thread, you were talking about to print MSIMessage. > > However, I prefer to print the raw data as I think the user of this interface > should be able to understand it as MSI-X messages. > > For instance, below is the data printed by "info msix". Just to clarify, I meant e.g for virtio-pci device, we can let it to print the mapping between vq and msix vectors: vq[0].msix_vector = 0 vq[1].msix_vector = 1 config.msix_vector = 2 ... But this could be added on top if you wish. Does this make sense? Thanks > > 0xfee01004 0x00000000 0x00000022 0x00000000 > 0xfee02004 0x00000000 0x00000023 0x00000000 > 0xfee01004 0x00000000 0x00000023 0x00000000 > 0xfee01004 0x00000000 0x00000021 0x00000000 > 0xfee02004 0x00000000 0x00000022 0x00000000 > 0x00000000 0x00000000 0x00000000 0x00000001 > 0x00000000 0x00000000 0x00000000 0x00000001 > > The 1st column is Message Lower Address. > > The 2nd column is Message Upper Address. > > The 3rd column is Message Data. > > The 4th column is Vector Control. > > In my opinion, this is equivalent to MSIMessage. > > 26 struct MSIMessage { > 27 uint64_t address; --> column 1 and 2 > 28 uint32_t data; --> column 3 > 29 }; > > > We use the similar way to read from Linux OS, e,g., given the address of MSI-X > cap, here is how we read from OS side. > > # busybox devmem 0xc1001000 32 > 0xFEE00000 > # busybox devmem 0xc1001004 32 > 0x00000000 > # busybox devmem 0xc1001008 32 > 0x00004049 > # busybox devmem 0xc100100c 32 > 0x00000000 > > Thank you very much! > > Dongli Zhang > >> >>> Adding an optional option to 'info pci' to limit to one device would be easy >>> though; that bit is probably easier than adding a new command. >> >> One interesting point is that MSI could be extended for other bus, (e.g MMIO). >> So "info msi" should be better I guess. >> >> >>> Figuring out the QMP representation of your entries might be harder - >>> and if this is strictly for debug, probably not worth it? >> >> I think so. >> >> Thanks >> >> >>> Dave >>> >>> >>>> Dongli Zhang >>>> >>>>>> 2. Is there any issue with output format? >>>>> If it's not for QMP, I guess it's not a part of ABI so it should be fine. >>>>> >>>>> >>>>>> 3. Is it fine to add only for HMP, but not QMP? >>>>> I think so. >>>>> >>>>> Thanks >>>>> >>>>> >>>>>> Thank you very much! >>>>>> >>>>>> Dongli Zhang >>>>>> >>>>>> >>>>>>