Hi,
On Thu, May 20, 2021 at 03:07:02PM +0200, Jean-Philippe Brucker wrote:
As planned during the vCPU hot-add discussions from previous LOD meetings, this prototype lets userspace handle PSCI calls from a guest.
To kick things off I've sent the Linux RFC to the public lists https://lore.kernel.org/kvmarm/20210608154805.216869-1-jean-philippe@linaro....
I've only sent the KVM bits to see if folks are strongly opposed to the idea. I'm guessing the next steps are:
(1) Discuss changes to the PSCI spec with ATG. The spec needs to recognize the new behavior in section 5.6 (and probably elsewhere): A core may be available for power-up or not. The mechanism by which the OS detects if a core can be powered up is IMPLEMENTATION DEFINED (we use ACPI _STA). If the core is not available, CPU_ON returns a new error (I've reused NOT_PRESENT -7 in my patch, to avoid introducing a new error code in PSCI).
(2) Send a new RFC for Qemu, which includes Salil's RFC + the additional PSCI support.
(3) Send the changes for Linux guests, both for ACPI and PSCI.
Thanks, Jean