Re: [PATCH v13 20/24] virt: gunyah: Add proxy-scheduled vCPUs

[Alex Elder <elder@linaro.org>]

On 5/9/23 3:47 PM, Elliot Berman wrote:
> Gunyah allows host virtual machines to schedule guest virtual machines
> and handle their MMIO accesses. vCPUs are presented to the host as a
> Gunyah resource and represented to userspace as a Gunyah VM function.
> 
> Creating the vcpu VM function will create a file descriptor that:
>   - can run an ioctl: GH_VCPU_RUN to schedule the guest vCPU until the
>     next interrupt occurs on the host or when the guest vCPU can no
>     longer be run.
>   - can be mmap'd to share a gh_vcpu_run structure which can look up the
>     reason why GH_VCPU_RUN returned and provide return values for MMIO
>     access.
> 
> Co-developed-by: Prakruthi Deepak Heragu <quic_pheragu@quicinc.com>
> Signed-off-by: Prakruthi Deepak Heragu <quic_pheragu@quicinc.com>
> Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>

To be honest I have spent less time immersed in the VCPU stuff
than I would like.

I have looked through this patch today, though, and with the
exception of a typo I point out, it looks generally good to me.

For now I'm going to give you this; I might take a closer look
at a future date when you have updated your code.

Acked-by: Alex Elder <elder@linaro.org>

> ---
>   Documentation/virt/gunyah/vm-manager.rst |  46 ++-
>   arch/arm64/gunyah/gunyah_hypercall.c     |  28 ++
>   drivers/virt/gunyah/Kconfig              |  11 +
>   drivers/virt/gunyah/Makefile             |   2 +
>   drivers/virt/gunyah/gunyah_vcpu.c        | 468 +++++++++++++++++++++++
>   drivers/virt/gunyah/vm_mgr.c             |   4 +
>   drivers/virt/gunyah/vm_mgr.h             |   1 +
>   include/linux/gunyah.h                   |  24 ++
>   include/uapi/linux/gunyah.h              | 128 +++++++
>   9 files changed, 710 insertions(+), 2 deletions(-)
>   create mode 100644 drivers/virt/gunyah/gunyah_vcpu.c
> 
> diff --git a/Documentation/virt/gunyah/vm-manager.rst b/Documentation/virt/gunyah/vm-manager.rst
> index 3b51bab9d793..6789d13fed14 100644
> --- a/Documentation/virt/gunyah/vm-manager.rst
> +++ b/Documentation/virt/gunyah/vm-manager.rst
> @@ -5,8 +5,7 @@ Virtual Machine Manager
>   =======================
>   
>   The Gunyah Virtual Machine Manager is a Linux driver to support launching
> -virtual machines using Gunyah. It presently supports launching non-proxy
> -scheduled Linux-like virtual machines.
> +virtual machines using Gunyah.
>   
>   Except for some basic information about the location of initial binaries,
>   most of the configuration about a Gunyah virtual machine is described in the
> @@ -98,3 +97,46 @@ GH_VM_START
>   ~~~~~~~~~~~
>   
>   This ioctl starts the VM.
> +
> +GH_VM_ADD_FUNCTION
> +~~~~~~~~~~~~~~~~~~
> +
> +This ioctl registers a Gunyah VM function with the VM manager. The VM function
> +is described with a &struct gh_fn_desc.type and some arguments for that type.
> +Typically, the function is added before the VM starts, but the function doesn't
> +"operate" until the VM starts with `GH_VM_START`_. For example, vCPU ioclts will

s/ioclts/ioctls/

> +all return an error until the VM starts because the vCPUs don't exist until the
> +VM is started. This allows the VMM to set up all the kernel functions needed for
> +the VM *before* the VM starts.
> +
> +.. kernel-doc:: include/uapi/linux/gunyah.h
> +   :identifiers: gh_fn_desc gh_fn_type
> +

. . .