Re: [RFC v2 0/4] Introduce MMIO/PIO dispatch file descriptors (ioregionfd)

[Stefan Hajnoczi <stefanha@redhat.com>]

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On Thu, Jan 28, 2021 at 09:32:19PM +0300, Elena Afanasova wrote:
> This patchset introduces a KVM dispatch mechanism which can be used 
> for handling MMIO/PIO accesses over file descriptors without returning 
> from ioctl(KVM_RUN). This allows device emulation to run in another task 
> separate from the vCPU task.
> 
> This is achieved through KVM vm ioctl for registering MMIO/PIO regions and 
> a wire protocol that KVM uses to communicate with a task handling an 
> MMIO/PIO access.

Hi Paolo,
This patch series makes changes to the somewhat tricky x86 MMIO/PIO code
and introduces a new ioctl(KVM_RUN) EINTR case. Please take a look if
you have time!

Reviews from anyone else are appreciated too!

Thanks,
Stefan

> 
> TODOs:
> * Implement KVM_EXIT_IOREGIONFD_FAILURE
> * Add non-x86 arch support
> * Add kvm-unittests
> 
> Elena Afanasova (4):
>   KVM: add initial support for KVM_SET_IOREGION
>   KVM: x86: add support for ioregionfd signal handling
>   KVM: add support for ioregionfd cmds/replies serialization
>   KVM: enforce NR_IOBUS_DEVS limit if kmemcg is disabled
> 
>  arch/x86/kvm/Kconfig          |   1 +
>  arch/x86/kvm/Makefile         |   1 +
>  arch/x86/kvm/x86.c            | 216 ++++++++++++++-
>  include/kvm/iodev.h           |  14 +
>  include/linux/kvm_host.h      |  34 +++
>  include/uapi/linux/ioregion.h |  32 +++
>  include/uapi/linux/kvm.h      |  23 ++
>  virt/kvm/Kconfig              |   3 +
>  virt/kvm/eventfd.c            |  25 ++
>  virt/kvm/eventfd.h            |  14 +
>  virt/kvm/ioregion.c           | 479 ++++++++++++++++++++++++++++++++++
>  virt/kvm/ioregion.h           |  15 ++
>  virt/kvm/kvm_main.c           |  68 ++++-
>  13 files changed, 905 insertions(+), 20 deletions(-)
>  create mode 100644 include/uapi/linux/ioregion.h
>  create mode 100644 virt/kvm/eventfd.h
>  create mode 100644 virt/kvm/ioregion.c
>  create mode 100644 virt/kvm/ioregion.h
> 
> -- 
> 2.25.1
> 

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