linux-kernel

Open Source and information security mailing list archives

Message-ID: <SN6PR04MB4527810F605C8ADE388E958286400@SN6PR04MB4527.namprd04.prod.outlook.com>
Date:   Tue, 19 Mar 2019 23:49:16 +0000
From:   Chaitanya Kulkarni <Chaitanya.Kulkarni@....com>
To:     Keith Busch <kbusch@...nel.org>,
        Maxim Levitsky <mlevitsk@...hat.com>
CC:     Fam Zheng <fam@...hon.net>, Keith Busch <keith.busch@...el.com>,
        Sagi Grimberg <sagi@...mberg.me>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        Wolfram Sang <wsa@...-dreams.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Liang Cunming <cunming.liang@...el.com>,
        Nicolas Ferre <nicolas.ferre@...rochip.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-nvme@...ts.infradead.org" <linux-nvme@...ts.infradead.org>,
        "David S . Miller" <davem@...emloft.net>,
        Jens Axboe <axboe@...com>,
        Alex Williamson <alex.williamson@...hat.com>,
        Kirti Wankhede <kwankhede@...dia.com>,
        Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Liu Changpeng <changpeng.liu@...el.com>,
        "Paul E . McKenney " <paulmck@...ux.ibm.com>,
        Amnon Ilan <ailan@...hat.com>, Christoph Hellwig <hch@....de>,
        John Ferlan <jferlan@...hat.com>
Subject: Re: your mail

Hi Keith,
On 03/19/2019 08:21 AM, Keith Busch wrote:
> On Tue, Mar 19, 2019 at 04:41:07PM +0200, Maxim Levitsky wrote:
>>    -> Share the NVMe device between host and guest.
>>       Even in fully virtualized configurations,
>>       some partitions of nvme device could be used by guests as block devices
>>       while others passed through with nvme-mdev to achieve balance between
>>       all features of full IO stack emulation and performance.
>>
>>    -> NVME-MDEV is a bit faster due to the fact that in-kernel driver
>>       can send interrupts to the guest directly without a context
>>       switch that can be expensive due to meltdown mitigation.
>>
>>    -> Is able to utilize interrupts to get reasonable performance.
>>       This is only implemented
>>       as a proof of concept and not included in the patches,
>>       but interrupt driven mode shows reasonable performance
>>
>>    -> This is a framework that later can be used to support NVMe devices
>>       with more of the IO virtualization built-in
>>       (IOMMU with PASID support coupled with device that supports it)
>
> Would be very interested to see the PASID support. You wouldn't even
> need to mediate the IO doorbells or translations if assigning entire
> namespaces, and should be much faster than the shadow doorbells.
>
> I think you should send 6/9 "nvme/pci: init shadow doorbell after each
> reset" separately for immediate inclusion.
>
> I like the idea in principle, but it will take me a little time to get
> through reviewing your implementation. I would have guessed we could
> have leveraged something from the existing nvme/target for the mediating
> controller register access and admin commands. Maybe even start with
> implementing an nvme passthrough namespace target type (we currently
> have block and file).

I have the code for the NVMeOf target passthru-ctrl, I think we can use 
that as it is if you are looking for the passthru for NVMeOF.

I'll post patch-series based on the latest code base soon.
>
> _______________________________________________
> Linux-nvme mailing list
> Linux-nvme@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-nvme
>

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives