From: Stefan Hajnoczi <stefanha@redhat.com>
To: 侯英乐 <houyingle@sudoinfotech.com>
Cc: jasowang <jasowang@redhat.com>,
David Hildenbrand <david@redhat.com>,
virtio-comment <virtio-comment@lists.oasis-open.org>,
Christoph Hellwig <hch@lst.de>, Keith Busch <kbusch@kernel.org>,
Kevin Wolf <kwolf@redhat.com>,
Klaus Jensen <k.jensen@samsung.com>,
sgarzare <sgarzare@redhat.com>,
"Michael S. Tsirkin" <mst@redhat.com>,
Alex Williamson <alex.williamson@redhat.com>
Subject: Re: Re: [virtio-comment] About adding a new device type virtio-nvme
Date: Wed, 18 Jan 2023 09:08:36 -0500 [thread overview]
Message-ID: <Y8f9ZLgPP2Ou9qWP@fedora> (raw)
In-Reply-To: <CB1D0D0BB5D3E5E6+2023011810151168808928@sudoinfotech.com>
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On Wed, Jan 18, 2023 at 10:15:12AM +0800, 侯英乐 wrote:
> On Tue, 17 Jan 2023 10:34:09 -0500, Stefan wrote:
>
> >On Tue, Jan 17, 2023 at 05:41:57PM +0800, 侯英乐 wrote:
> >> On Tue, 17 Jan 2023 09:32:05 +0100，David wrote：
> >> >On 17.01.23 03:04, 侯英乐 wrote:
> >>
> >>
> >>
> >> >> virtio-nvme advantages :
> >> >> 1) live migration
> >> >> 2) support remote storage
> >>
> >>
> >>
> >> >At least 1) is an implementation detail in the NVME implementation in
> >> >the hypervisor. I suspect 2) in a similar way, or is there a fundamental
> >> >issue with that?
> >>
> >>
> >>
> >> >One problematic thing about the NVME implementation in QEMU is that it
> >> >will pin (via vfio) all guest RAM. Could that be avoided using
> >> >virtio-NVME, or what exactly would be the difference between virtio-nvme
> >> >and ordinary NVME?
> >>
> >>
> >>
> >> In the virtualization scenario where devices are offload to hardware：
> >>
> >>
> >> NVME：
> >> ---------------------------------------------------------------------------------------------------------------------
> >> _____________________________________________________________________________
> >> | ___________________________________________________________ |
> >> | | _____________________________________________________ | |
> >> | | | | | |
> >> | | | __________________________________ | | |
> >> | | | | ______ | | | | ______
> >> | | | User | | Mem |-----------------------|----|-|----|-----> | |
> >> | | | | |______| SPDK | | | | (gVA) |______|
> >> | | | | (gVA) | | | | | |
> >> | | | |______|___________________________| | | | | |
> >> | | |--GuestOS----------|--------------------------------| | | | |
> >> | | | ______\/__________________________ | | | | |
> >> | | VM | | VFIO | | | | | |
> >> | User | | Kernel |___________ __________________| | | | | |
> >> | | | | vfio-pci | | | | | | | |
> >> | | | | (gIOVA) | | vfio_iommu_type1 | | | | | |
> >> Software | | | |______|____|___|__________________| | | | | |
> >> | | |___________________|________________________________| | | | |
> >> | | ___________________|________________________________ | | | |
> >> | | | ______|____ __________________ | | | \/ \/
> >> | | | | \/ | | | | | | ______
> >> | | | | NVME | | vIOMMU | | | | | |
> >> | | | QEMU | Instance | | --|----|-|----|-----> |______|
> >> | | | | (gIOVA) | | (gIOVA-->gPA) | | | | (gPA) | |
> >> | | | |_____|_____| |__________________| | | | | |
> >> | | |__________________|_________________________________| | | | |
> >> | |_______________________|___________________________________| | | |
> >> |---HostOS---------------------------|----------------------------------------| | |
> >> | _______________________|___________________________________ | | |
> >> | | | | | | |
> >> | | | VFIO | | | |
> >> | Kernel |_______________________|_____ _________________________| | | |
> >> | | \/ | | | | | |
> >> | | vfio-pci | | vfio_iommu_type1 | | | |
> >> | | | | | | | | |
> >> | |_______________________|_____|___|_________________________| | | |
> >> |____________________________________|________________________________________| | |
> >> -----------------------------------------------|-------------------------------------------------|----|--------------
> >> ____________________________________\/____ _________________________ ___\/___\/___________
> >> | | | | | | | | | |
> >> Hardware | | | DMA (gIOVA) --|---|-> IOMMU --|---------|->|______| |
> >> | | |_____________________________| | (gIOVA-->hPA) | (hPA) | Physical Memory |
> >> | DPU | | |_________________________| |_____________________|
> >> | | NVME-of |
> >> | |__________________________________|
> >> | | |
> >> |___________________________|______________|
> >> --------------------------------------|------------------------------------------------------------------------------
> >> | TCP (RDMA, and so on)
> >> ______________v__________
> >> | |
> >> Remote storage | |
> >> | Network Storage |
> >> | |
> >> |_________________________|
> >>
> >> ---------------------------------------------------------------------------------------------------------------------
> >>
> >>
> >> It is difficult to implement PCIe passthrough live migration.
>
>
>
>
> >Linux commit 115dcec65f61d53e25e1bed5e380468b30f98b14 ("vfio: Define
> >device migration protocol v2") defines the VFIO migration API and it's
> >implemented by several drivers in the kernel.
>
>
> Yes, this commit supports VFIO live migration, but the feature is a work in progress,
> recent submission: https://lore.kernel.org/all/20230116141135.12021-10-avihaih@nvidia.com/
>
>
> >Can you explain the difficulty of implementing PCIe passthrough live
> >migration in more detail?
>
> VFIO live migration requires IOMMU to support dirty page tracking. Currently,
> no IOMMU device supports this feature. So, VFIO live migration will take a long time.
> Detailed information reference：https://www.qemu.org/docs/master/devel/vfio-migration.html
Can physical devices can do their own dirty page tracking in the
meantime since they know which pages are being written to?
I have CCed Alex Williamson regarding VFIO.
Stefan
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next prev parent reply other threads:[~2023-01-18 14:08 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-11 3:21 [virtio-comment] About adding a new device type virtio-nvme 侯英乐
2023-01-11 15:16 ` Stefan Hajnoczi
2023-01-17 2:04 ` 侯英乐
2023-01-17 8:32 ` David Hildenbrand
2023-01-17 9:30 ` 侯英乐
[not found] ` <202301171730174296359@sudoinfotech.com>
2023-01-17 9:41 ` 侯英乐
2023-01-17 15:34 ` Stefan Hajnoczi
2023-01-17 15:47 ` David Hildenbrand
2023-01-18 2:38 ` 侯英乐
2023-01-18 2:15 ` 侯英乐
2023-01-18 14:08 ` Stefan Hajnoczi [this message]
2023-01-19 8:31 ` 侯英乐
2023-01-18 14:14 ` Stefan Hajnoczi
2023-01-19 3:40 ` Jason Wang
2023-01-19 16:59 ` Stefan Hajnoczi
2023-01-19 9:03 ` 侯英乐
2023-01-19 17:03 ` Stefan Hajnoczi
2023-01-19 3:38 ` Jason Wang
2023-01-19 7:22 ` 侯英乐
2023-01-17 16:01 ` Stefan Hajnoczi
[not found] ` <20230117162114.GA24976@lst.de>
2023-01-17 16:53 ` Stefan Hajnoczi
2023-01-18 11:22 ` Michael S. Tsirkin
2023-01-18 2:49 ` 侯英乐
2023-02-05 12:33 ` Michael S. Tsirkin
2023-02-09 3:28 ` 侯英乐
2023-02-17 3:01 ` Parav Pandit
2023-01-19 11:42 ` Michael S. Tsirkin
2023-01-29 3:32 ` 侯英乐
2023-01-30 20:30 ` Stefan Hajnoczi
2023-01-17 17:19 ` Max Gurtovoy
2023-01-18 3:23 ` 侯英乐
2023-01-18 10:09 ` Max Gurtovoy
2023-01-18 11:12 ` Michael S. Tsirkin
2023-01-18 11:27 ` Max Gurtovoy
2023-01-18 13:29 ` Michael S. Tsirkin
2023-01-19 10:19 ` 侯英乐
2023-01-19 10:33 ` Max Gurtovoy
2023-01-19 11:02 ` 侯英乐
2023-01-19 17:15 ` Stefan Hajnoczi
2023-01-18 10:28 ` Michael S. Tsirkin
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