[kvmtool,v2,00/13] Implement reset of virtio devices

Message

Julien Thierry Jan. 10, 2019, 2:12 p.m. UTC

Hi,

This series was developped by Jean-Philippe and is needed for a series
I'll be posting shortly after to load firmwares on arm kvmtool.

Currently, when a guest tries to reset a device, a lot of ressources
aren't reset (threads keep running, virtio queue keep their state, etc).

When the guest only does the reset to initialize the device and there
were no previous users, there is no noticeable issue. But when a guest
has a firmare + Linux, if the firmware uses a virtio device, Linux will
fail to probe that device.

This series aim to properly reset the virtio resources when the guests
requests it.

Reset of net vhost is unsupported for now.

Patch 1 is a bug fix on ioeventfd
Patch 2-6 provide the core support so devices can implement their reset
Patch 7-13 implements the reset for the various virtio devices

Changes since v1[1]:
- Fix build issue by removing reference to VIRTIO_CONFIG_S_NEEDS_RESET

[1] https://marc.info/?l=kvm&m=154392208726108&w=2

Thanks,

Julien

-->

Jean-Philippe Brucker (13):
  ioeventfd: Fix removal of ioeventfd
  virtio: Implement notify_status
  virtio: Add get_vq_count() callback
  virtio: Add get_vq() callback
  virtio: Add exit_vq() callback
  virtio: Add reset() callback
  net/uip: Add exit function
  virtio/net: Clean virtqueue state
  virtio/net: Implement device and virtqueue reset
  virtio/blk: Reset virtqueue
  threadpool: Add cancel() function
  virtio/p9: Implement reset
  virtio/console: Implement reset

 include/kvm/threadpool.h  |   2 +
 include/kvm/uip.h         |   6 ++
 include/kvm/virtio-mmio.h |   1 +
 include/kvm/virtio-pci.h  |   1 +
 include/kvm/virtio.h      |  29 ++++++-
 ioeventfd.c               |   6 +-
 net/uip/core.c            |  17 ++++
 net/uip/dhcp.c            |   6 ++
 net/uip/tcp.c             |  54 ++++++++++---
 net/uip/udp.c             |  41 ++++++++--
 util/threadpool.c         |  25 +++++-
 virtio/9p.c               |  33 +++++++-
 virtio/balloon.c          |  17 +++-
 virtio/blk.c              |  84 ++++++++++++++------
 virtio/console.c          |  49 ++++++++----
 virtio/core.c             |  42 ++++++++++
 virtio/mmio.c             |  52 +++++++++----
 virtio/net.c              | 195 +++++++++++++++++++++++++++++++++-------------
 virtio/pci.c              |  49 ++++++++----
 virtio/rng.c              |  12 ++-
 virtio/scsi.c             |  17 +++-
 21 files changed, 581 insertions(+), 157 deletions(-)

--
1.9.1

Comments

Will Deacon Jan. 22, 2019, 7:07 a.m. UTC | #1

On Thu, Jan 10, 2019 at 02:12:37PM +0000, Julien Thierry wrote:
> This series was developped by Jean-Philippe and is needed for a series
> I'll be posting shortly after to load firmwares on arm kvmtool.
> 
> Currently, when a guest tries to reset a device, a lot of ressources
> aren't reset (threads keep running, virtio queue keep their state, etc).
> 
> When the guest only does the reset to initialize the device and there
> were no previous users, there is no noticeable issue. But when a guest
> has a firmare + Linux, if the firmware uses a virtio device, Linux will
> fail to probe that device.
> 
> This series aim to properly reset the virtio resources when the guests
> requests it.
> 
> Reset of net vhost is unsupported for now.
> 
> Patch 1 is a bug fix on ioeventfd
> Patch 2-6 provide the core support so devices can implement their reset
> Patch 7-13 implements the reset for the various virtio devices

Cheers, I'll pick this up. There's a vague comment in patch 10 about aio
being busted. If that's the case then we should either fix it or remove
it...

Will

Jean-Philippe Brucker Jan. 22, 2019, 11:51 a.m. UTC | #2

On 22/01/2019 07:07, Will Deacon wrote:
> On Thu, Jan 10, 2019 at 02:12:37PM +0000, Julien Thierry wrote:
>> This series was developped by Jean-Philippe and is needed for a series
>> I'll be posting shortly after to load firmwares on arm kvmtool.
>>
>> Currently, when a guest tries to reset a device, a lot of ressources
>> aren't reset (threads keep running, virtio queue keep their state, etc).
>>
>> When the guest only does the reset to initialize the device and there
>> were no previous users, there is no noticeable issue. But when a guest
>> has a firmare + Linux, if the firmware uses a virtio device, Linux will
>> fail to probe that device.
>>
>> This series aim to properly reset the virtio resources when the guests
>> requests it.
>>
>> Reset of net vhost is unsupported for now.
>>
>> Patch 1 is a bug fix on ioeventfd
>> Patch 2-6 provide the core support so devices can implement their reset
>> Patch 7-13 implements the reset for the various virtio devices
> 
> Cheers, I'll pick this up. There's a vague comment in patch 10 about aio
> being busted. If that's the case then we should either fix it or remove
> it...

Thanks! I think my main concern with aio was that the iocb structures
are allocated on the stack, and get trashed after io_submit(). The aio
man says that control block should remain valid until the I/O completes
(which might still apply even if we're using raw iocb instead of aiocb -
I can't find where the kernel copies those buffers). I'll take a better
look and implement reset if possible.

Thanks,
Jean