Hi James,
From: James Morse [mailto:james.morse@arm.com] Sent: Thursday, September 1, 2022 12:00 PM To: Salil Mehta salil.mehta@huawei.com; gankulkarni@os.amperecomputing.com Cc: linaro-open-discussions@op-lists.linaro.org; Lorenzo Pieralisi lorenzo.pieralisi@linaro.org; Jonathan Cameron jonathan.cameron@huawei.com; mehta.salil.lnk@gmail.com Subject: Re: [Linaro-open-discussions] Re: ARM64 virt CPU HP - plan
Hi Salil,
On 01/09/2022 10:02, Salil Mehta wrote:
From: Salil Mehta via Linaro-open-discussions
Ideally, I should be able to share the code by COB tomorrow if I find no blockers during testing (which I do not see as of now).
Beware the WFI in user-space support that is needed for implementing
CPU_SUSPEND
is a little different from the previous version. From memory the change is how
the
vCPU gets restarted....
I see. thanks for sharing this info. It might be helpful if you have reference to lore.kernel patches where it got changed?
Aah, got it. Perhaps this patch? Yes, I can see what you mean.
[RFC PATCH 2/5] KVM: arm64: Move WFI execution to check_vcpu_requests()
https://lore.kernel.org/kvm/20210608154805.216869-1-jean-philippe@linaro.or g/T/#mf696d88845f7467f4c0b7388becfdd23e3437c78
Yes, that was what Jean's qemu work originally supported, but since then mainline has merged 7b33a09d036f ("KVM: arm64: Add support for userspace to suspend a vCPU"), which is similar, but different.
Most of that patch from Jean got folded out in the rebase, and mainline now has some difference in the way the user-space interface behaves.
I see. So if I got you correctly, we might need some change in the userspace PSCI QEMU handling as well over the Jean's PSCI patches (as they might not work out-of-the-box) to reflect the merged change in the mainline kernel?
Thanks Salil.