[PATCH V11 00/17] riscv: Add Native/Paravirt qspinlock support

[Conor Dooley]

On Tue, Sep 12, 2023 at 09:33:57AM +0800, Guo Ren wrote:
> On Mon, Sep 11, 2023 at 8:53 PM Conor Dooley <conor.dooley at microchip.com> wrote:

> > I added the new "riscv,isa-extensions" property in part to make
> > communicating vendor extensions like this easier. Please try to use
> > that. "qspinlock" is software configuration though, the vendor extension
> > should focus on the guarantee of strong forward progress, since that is
> > the non-standard aspect of your IP.
> 
> The qspinlock contains three paths:
>  - Native qspinlock, this is your strong forward progress.
>  - virt_spin_lock, for KVM guest when paravirt qspinlock disabled.
>    https://lore.kernel.org/linux-riscv/20230910082911.3378782-9-guoren@kernel.org/
>  - paravirt qspinlock, for KVM guest
> 
> So, we need a software configuration here, "riscv,isa-extensions" is
> all about vendor extension.

Ah right, yes it would only be able to be used to determine whether or
not the platform is capable of supporting these spinlocks, not whether or
not the kernel is a guest. I think I misinterpreted that snippet you posted,
thinking you were trying to disable your new spinlock for KVM, sorry.
On that note though, what about other sorts of guests? Will non-KVM
guests not also want to use this virt spinlock?

Thanks,
Conor.
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