Re: [PATCH v2 2/3] KVM: PPC: Book3S HV: Add preempt_disable() around virtual-mode HPTE bit-lock users

[Shrikanth Hegde]

On 10/5/26 11:57 PM, Amit Machhiwal wrote:
> Hi Shrikanth,
>
> Thanks for the review.  Please find my responses inline below.

> > I don't like this sprinkling of preempt disable/enable.
> > Is there not a way to embedd this in try_lock_hpte/unlock_hpte?
>
> I understand the scattering of preempt_disable()/preempt_enable() looks ugly.
> But there are two blockers for that approach:
>
> 1. The real-mode hcall dispatch table (hcall_real_table in
>     book3s_hv_rmhandlers.S) calls kvmppc_h_enter(), kvmppc_h_remove(),
>     kvmppc_h_bulk_remove() and others in book3s_hv_rm_mmu.c, which all call
>     try_lock_hpte() from real mode.  Adding preempt_disable() inside
>     try_lock_hpte() would affect those real-mode callers, which brings us to your
>     second point.

Fair enough.

Reviewed-by: Shrikanth Hegde <sshegde@xxxxxxxxxxxxx>