Re: [PATCH v1 0/5] target/arm: Handle psci calls in userspace

[Shaoqin Huang]

Hi Salil,

On 6/26/23 21:42, Salil Mehta wrote:
> > From: Shaoqin Huang <shahuang@redhat.com>
> > Sent: Monday, June 26, 2023 7:49 AM
> > To: qemu-devel@nongnu.org; qemu-arm@nongnu.org
> > Cc: oliver.upton@linux.dev; Salil Mehta <salil.mehta@huawei.com>;
> > james.morse@arm.com; gshan@redhat.com; Shaoqin Huang <shahuang@redhat.com>;
> > Cornelia Huck <cohuck@redhat.com>; kvm@vger.kernel.org; Michael S. Tsirkin
> > <mst@redhat.com>; Paolo Bonzini <pbonzini@redhat.com>; Peter Maydell
> > <peter.maydell@linaro.org>
> > Subject: [PATCH v1 0/5] target/arm: Handle psci calls in userspace
> >
> > The userspace SMCCC call filtering[1] provides the ability to forward the SMCCC
> > calls to the userspace. The vCPU hotplug[2] would be the first legitimate use
> > case to handle the psci calls in userspace, thus the vCPU hotplug can deny the
> > PSCI_ON call if the vCPU is not present now.
> >
> > This series try to enable the userspace SMCCC call filtering, thus can handle
> > the SMCCC call in userspace. The first enabled SMCCC call is psci call, by using
> > the new added option 'user-smccc', we can enable handle psci calls in userspace.
> >
> > qemu-system-aarch64 -machine virt,user-smccc=on
> >
> > This series reuse the qemu implementation of the psci handling, thus the
> > handling process is very simple. But when handling psci in userspace when using
> > kvm, the reset vcpu process need to be taking care, the detail is included in
> > the patch05.
>
> This change in intended for VCPU Hotplug and we are duplicating the code
> we are working on. Unless this change is also intended for any other
> feature I would request you to defer this.

Thanks for sharing me the information. I'm not intended for merging this 
series, but discuss something about the VCPU Hotplug, since I'm also 
following the work of vCPU Hotplug.

Just curious, what is your plan to update a new version of VCPU Hotplug 
which is based on the userspace SMCCC filtering?

Thanks,
Shaoqin

> Thanks
> Salil

--
Shaoqin