* Re: [RFC v2 01/13] mm: export zap_page_range() for driver use
@ 2020-12-23 6:32 Yongji Xie
2020-12-23 8:13 ` Christoph Hellwig
0 siblings, 1 reply; 5+ messages in thread
From: Yongji Xie @ 2020-12-23 6:32 UTC (permalink / raw)
To: Christoph Hellwig
Cc: Michael S. Tsirkin, Jason Wang, Stefan Hajnoczi, sgarzare,
Parav Pandit, akpm, Randy Dunlap, Matthew Wilcox, viro, axboe,
bcrl, corbet, virtualization, netdev, kvm, linux-aio,
linux-fsdevel, linux-mm
On Tue, Dec 22, 2020 at 11:44 PM Christoph Hellwig <hch@infradead.org> wrote:
>
> On Tue, Dec 22, 2020 at 10:52:09PM +0800, Xie Yongji wrote:
> > Export zap_page_range() for use in VDUSE.
>
> Err, no. This has absolutely no business being used by drivers.
Now I want to map/unmap some pages in an userland vma dynamically. The
vm_insert_page() is being used for mapping. In the unmapping case, it
looks like the zap_page_range() does what I want. So I export it.
Otherwise, we need some ways to notify userspace to trigger it with
madvise(MADV_DONTNEED), which might not be able to meet all our needs.
For example, unmapping some pages in a memory shrinker function.
So I'd like to know what's the limitation to use zap_page_range() in a
module. And if we can't use it in a module, is there any acceptable
way to achieve that?
Thanks.
Yongji
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [RFC v2 01/13] mm: export zap_page_range() for driver use
2020-12-23 6:32 [RFC v2 01/13] mm: export zap_page_range() for driver use Yongji Xie
@ 2020-12-23 8:13 ` Christoph Hellwig
2020-12-23 14:21 ` [External] " Yongji Xie
0 siblings, 1 reply; 5+ messages in thread
From: Christoph Hellwig @ 2020-12-23 8:13 UTC (permalink / raw)
To: Yongji Xie
Cc: Christoph Hellwig, Michael S. Tsirkin, Jason Wang,
Stefan Hajnoczi, sgarzare, Parav Pandit, akpm, Randy Dunlap,
Matthew Wilcox, viro, axboe, bcrl, corbet, virtualization,
netdev, kvm, linux-aio, linux-fsdevel, linux-mm
On Wed, Dec 23, 2020 at 02:32:07PM +0800, Yongji Xie wrote:
> Now I want to map/unmap some pages in an userland vma dynamically. The
> vm_insert_page() is being used for mapping. In the unmapping case, it
> looks like the zap_page_range() does what I want. So I export it.
> Otherwise, we need some ways to notify userspace to trigger it with
> madvise(MADV_DONTNEED), which might not be able to meet all our needs.
> For example, unmapping some pages in a memory shrinker function.
>
> So I'd like to know what's the limitation to use zap_page_range() in a
> module. And if we can't use it in a module, is there any acceptable
> way to achieve that?
I think the anser is: don't play funny games with unmapped outside of
munmap. Especially as synchronization is very hard to get right.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [External] Re: [RFC v2 01/13] mm: export zap_page_range() for driver use
2020-12-23 8:13 ` Christoph Hellwig
@ 2020-12-23 14:21 ` Yongji Xie
0 siblings, 0 replies; 5+ messages in thread
From: Yongji Xie @ 2020-12-23 14:21 UTC (permalink / raw)
To: Christoph Hellwig
Cc: Michael S. Tsirkin, Jason Wang, Stefan Hajnoczi, sgarzare,
Parav Pandit, akpm, Randy Dunlap, Matthew Wilcox, viro, axboe,
bcrl, corbet, virtualization, netdev, kvm, linux-aio,
linux-fsdevel, linux-mm
On Wed, Dec 23, 2020 at 4:13 PM Christoph Hellwig <hch@infradead.org> wrote:
>
> On Wed, Dec 23, 2020 at 02:32:07PM +0800, Yongji Xie wrote:
> > Now I want to map/unmap some pages in an userland vma dynamically. The
> > vm_insert_page() is being used for mapping. In the unmapping case, it
> > looks like the zap_page_range() does what I want. So I export it.
> > Otherwise, we need some ways to notify userspace to trigger it with
> > madvise(MADV_DONTNEED), which might not be able to meet all our needs.
> > For example, unmapping some pages in a memory shrinker function.
> >
> > So I'd like to know what's the limitation to use zap_page_range() in a
> > module. And if we can't use it in a module, is there any acceptable
> > way to achieve that?
>
> I think the anser is: don't play funny games with unmapped outside of
> munmap. Especially as synchronization is very hard to get right.
OK, I will try to let userspace do this.
Thanks,
Yongji
^ permalink raw reply [flat|nested] 5+ messages in thread
* [RFC v2 00/13] Introduce VDUSE - vDPA Device in Userspace
@ 2020-12-22 14:52 Xie Yongji
2020-12-22 14:52 ` [RFC v2 01/13] mm: export zap_page_range() for driver use Xie Yongji
0 siblings, 1 reply; 5+ messages in thread
From: Xie Yongji @ 2020-12-22 14:52 UTC (permalink / raw)
To: mst, jasowang, stefanha, sgarzare, parav, akpm, rdunlap, willy,
viro, axboe, bcrl, corbet
Cc: virtualization, netdev, kvm, linux-aio, linux-fsdevel, linux-mm
This series introduces a framework, which can be used to implement
vDPA Devices in a userspace program. The work consist of two parts:
control path forwarding and data path offloading.
In the control path, the VDUSE driver will make use of message
mechnism to forward the config operation from vdpa bus driver
to userspace. Userspace can use read()/write() to receive/reply
those control messages.
In the data path, the core is mapping dma buffer into VDUSE
daemon's address space, which can be implemented in different ways
depending on the vdpa bus to which the vDPA device is attached.
In virtio-vdpa case, we implements a MMU-based on-chip IOMMU driver with
bounce-buffering mechanism to achieve that. And in vhost-vdpa case, the dma
buffer is reside in a userspace memory region which can be shared to the
VDUSE userspace processs via transferring the shmfd.
The details and our user case is shown below:
------------------------ ------------------------- ----------------------------------------------
| Container | | QEMU(VM) | | VDUSE daemon |
| --------- | | ------------------- | | ------------------------- ---------------- |
| |dev/vdx| | | |/dev/vhost-vdpa-x| | | | vDPA device emulation | | block driver | |
------------+----------- -----------+------------ -------------+----------------------+---------
| | | |
| | | |
------------+---------------------------+----------------------------+----------------------+---------
| | block device | | vhost device | | vduse driver | | TCP/IP | |
| -------+-------- --------+-------- -------+-------- -----+---- |
| | | | | |
| ----------+---------- ----------+----------- -------+------- | |
| | virtio-blk driver | | vhost-vdpa driver | | vdpa device | | |
| ----------+---------- ----------+----------- -------+------- | |
| | virtio bus | | | |
| --------+----+----------- | | | |
| | | | | |
| ----------+---------- | | | |
| | virtio-blk device | | | | |
| ----------+---------- | | | |
| | | | | |
| -----------+----------- | | | |
| | virtio-vdpa driver | | | | |
| -----------+----------- | | | |
| | | | vdpa bus | |
| -----------+----------------------+---------------------------+------------ | |
| ---+--- |
-----------------------------------------------------------------------------------------| NIC |------
---+---
|
---------+---------
| Remote Storages |
-------------------
We make use of it to implement a block device connecting to
our distributed storage, which can be used both in containers and
VMs. Thus, we can have an unified technology stack in this two cases.
To test it with null-blk:
$ qemu-storage-daemon \
--chardev socket,id=charmonitor,path=/tmp/qmp.sock,server,nowait \
--monitor chardev=charmonitor \
--blockdev driver=host_device,cache.direct=on,aio=native,filename=/dev/nullb0,node-name=disk0 \
--export vduse-blk,id=test,node-name=disk0,writable=on,vduse-id=1,num-queues=16,queue-size=128
The qemu-storage-daemon can be found at https://github.com/bytedance/qemu/tree/vduse
Future work:
- Improve performance (e.g. zero copy implementation in datapath)
- Config interrupt support
- Userspace library (find a way to reuse device emulation code in qemu/rust-vmm)
This is now based on below series:
https://lore.kernel.org/netdev/20201112064005.349268-1-parav@nvidia.com/
V1 to V2:
- Add vhost-vdpa support
- Add some documents
- Based on the vdpa management tool
- Introduce a workqueue for irq injection
- Replace interval tree with array map to store the iova_map
Xie Yongji (13):
mm: export zap_page_range() for driver use
eventfd: track eventfd_signal() recursion depth separately in different cases
eventfd: Increase the recursion depth of eventfd_signal()
vdpa: Remove the restriction that only supports virtio-net devices
vdpa: Pass the netlink attributes to ops.dev_add()
vduse: Introduce VDUSE - vDPA Device in Userspace
vduse: support get/set virtqueue state
vdpa: Introduce process_iotlb_msg() in vdpa_config_ops
vduse: Add support for processing vhost iotlb message
vduse: grab the module's references until there is no vduse device
vduse/iova_domain: Support reclaiming bounce pages
vduse: Add memory shrinker to reclaim bounce pages
vduse: Introduce a workqueue for irq injection
Documentation/driver-api/vduse.rst | 91 ++
Documentation/userspace-api/ioctl/ioctl-number.rst | 1 +
drivers/vdpa/Kconfig | 8 +
drivers/vdpa/Makefile | 1 +
drivers/vdpa/vdpa.c | 2 +-
drivers/vdpa/vdpa_sim/vdpa_sim.c | 3 +-
drivers/vdpa/vdpa_user/Makefile | 5 +
drivers/vdpa/vdpa_user/eventfd.c | 229 ++++
drivers/vdpa/vdpa_user/eventfd.h | 48 +
drivers/vdpa/vdpa_user/iova_domain.c | 517 ++++++++
drivers/vdpa/vdpa_user/iova_domain.h | 103 ++
drivers/vdpa/vdpa_user/vduse.h | 59 +
drivers/vdpa/vdpa_user/vduse_dev.c | 1373 ++++++++++++++++++++
drivers/vhost/vdpa.c | 34 +-
fs/aio.c | 3 +-
fs/eventfd.c | 20 +-
include/linux/eventfd.h | 5 +-
include/linux/vdpa.h | 11 +-
include/uapi/linux/vdpa.h | 1 +
include/uapi/linux/vduse.h | 119 ++
mm/memory.c | 1 +
21 files changed, 2598 insertions(+), 36 deletions(-)
create mode 100644 Documentation/driver-api/vduse.rst
create mode 100644 drivers/vdpa/vdpa_user/Makefile
create mode 100644 drivers/vdpa/vdpa_user/eventfd.c
create mode 100644 drivers/vdpa/vdpa_user/eventfd.h
create mode 100644 drivers/vdpa/vdpa_user/iova_domain.c
create mode 100644 drivers/vdpa/vdpa_user/iova_domain.h
create mode 100644 drivers/vdpa/vdpa_user/vduse.h
create mode 100644 drivers/vdpa/vdpa_user/vduse_dev.c
create mode 100644 include/uapi/linux/vduse.h
--
2.11.0
^ permalink raw reply [flat|nested] 5+ messages in thread* [RFC v2 01/13] mm: export zap_page_range() for driver use
2020-12-22 14:52 [RFC v2 00/13] Introduce VDUSE - vDPA Device in Userspace Xie Yongji
@ 2020-12-22 14:52 ` Xie Yongji
2020-12-22 15:44 ` Christoph Hellwig
0 siblings, 1 reply; 5+ messages in thread
From: Xie Yongji @ 2020-12-22 14:52 UTC (permalink / raw)
To: mst, jasowang, stefanha, sgarzare, parav, akpm, rdunlap, willy,
viro, axboe, bcrl, corbet
Cc: virtualization, netdev, kvm, linux-aio, linux-fsdevel, linux-mm
Export zap_page_range() for use in VDUSE.
Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
---
mm/memory.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/mm/memory.c b/mm/memory.c
index 7d608765932b..edd2d6497bb3 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1542,6 +1542,7 @@ void zap_page_range(struct vm_area_struct *vma, unsigned long start,
mmu_notifier_invalidate_range_end(&range);
tlb_finish_mmu(&tlb, start, range.end);
}
+EXPORT_SYMBOL(zap_page_range);
/**
* zap_page_range_single - remove user pages in a given range
--
2.11.0
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [RFC v2 01/13] mm: export zap_page_range() for driver use
2020-12-22 14:52 ` [RFC v2 01/13] mm: export zap_page_range() for driver use Xie Yongji
@ 2020-12-22 15:44 ` Christoph Hellwig
0 siblings, 0 replies; 5+ messages in thread
From: Christoph Hellwig @ 2020-12-22 15:44 UTC (permalink / raw)
To: Xie Yongji
Cc: mst, jasowang, stefanha, sgarzare, parav, akpm, rdunlap, willy,
viro, axboe, bcrl, corbet, virtualization, netdev, kvm,
linux-aio, linux-fsdevel, linux-mm
On Tue, Dec 22, 2020 at 10:52:09PM +0800, Xie Yongji wrote:
> Export zap_page_range() for use in VDUSE.
Err, no. This has absolutely no business being used by drivers.
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2020-12-23 14:22 UTC | newest]
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2020-12-23 6:32 [RFC v2 01/13] mm: export zap_page_range() for driver use Yongji Xie
2020-12-23 8:13 ` Christoph Hellwig
2020-12-23 14:21 ` [External] " Yongji Xie
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2020-12-22 14:52 [RFC v2 00/13] Introduce VDUSE - vDPA Device in Userspace Xie Yongji
2020-12-22 14:52 ` [RFC v2 01/13] mm: export zap_page_range() for driver use Xie Yongji
2020-12-22 15:44 ` Christoph Hellwig
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