Re: [PATCH v2 2/3] LoongArch: Add paravirt support with vcpu_is_preempted() in guest side

[Jürgen Groß]

On 24.11.25 07:33, Huacai Chen wrote:
> Hi, Bibo,
>
> On Mon, Nov 24, 2025 at 11:54 AM Bibo Mao <maobibo@xxxxxxxxxxx> wrote:
> > Function vcpu_is_preempted() is used to check whether vCPU is preempted
> > or not. Here add implementation with vcpu_is_preempted() when option
> > CONFIG_PARAVIRT is enabled.
> >
> > Signed-off-by: Bibo Mao <maobibo@xxxxxxxxxxx>
> > ---
> >   arch/loongarch/include/asm/qspinlock.h |  5 +++++
> >   arch/loongarch/kernel/paravirt.c       | 16 ++++++++++++++++
> >   2 files changed, 21 insertions(+)
> >
> > diff --git a/arch/loongarch/include/asm/qspinlock.h b/arch/loongarch/include/asm/qspinlock.h
> > index e76d3aa1e1eb..9a5b7ba1f4cb 100644
> > --- a/arch/loongarch/include/asm/qspinlock.h
> > +++ b/arch/loongarch/include/asm/qspinlock.h
> > @@ -34,6 +34,11 @@ static inline bool virt_spin_lock(struct qspinlock *lock)
> >          return true;
> >   }
> >
> > +#ifdef CONFIG_SMP
> > +#define vcpu_is_preempted      vcpu_is_preempted
> > +bool vcpu_is_preempted(int cpu);
> In V1 there is a build error because you reference mp_ops, so in V2
> you needn't put it in CONFIG_SMP.
> On the other hand, even if you really build a UP guest kernel, when
> multiple guests run together, you probably need vcpu_is_preemtped.

I don't think so. When the UP guest's vcpu is preempted, who will use this
function?


Juergen

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