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

[Salil Mehta via <qemu-devel@nongnu.org>]

> 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
Salil