linux-kernel - Re: [PATCH 1/2] KVM: X86: Fix setup the virt_spin_lock

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Date:   Tue, 27 Mar 2018 08:52:18 +0800
From:   Wanpeng Li <kernellwp@...il.com>
To:     Davidlohr Bueso <dave@...olabs.net>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>, kvm <kvm@...r.kernel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        "Radim Kr??m???" <rkrcmar@...hat.com>,
        Davidlohr Bueso <dbueso@...e.de>
Subject: Re: [PATCH 1/2] KVM: X86: Fix setup the virt_spin_lock_key before
 static key get initialized

2018-03-27 6:32 GMT+08:00 Davidlohr Bueso <dave@...olabs.net>:
> On Mon, 26 Mar 2018, Wanpeng Li wrote:
>
>> I didn't see any issue when testing this patch, could you elaborate
>> what's the bulky mechanism and how it conflicts with early smp bootup
>> stages? In addition, do you mean the xen fix is also not suitable?
>
>
> I have nothing against your patch (or the xen one for that matter), other
> than
> the fact that both seem like band-aid solutions to being able to move up the
> jump
> label init call. I was actually peddling a similar patch but didn't want to
> add
> the extra callback just for that -- at least xen already had
> smp_ops.smp_prepare_cpus.
>
> Instead of dropping the patches in -tip (ie: delaying the feature), I have
> nothing
> against these fixes being merged. If a better solution is available later,
> we can
> always move dealing with virt_spin_lock_key back into
> smp_prepare_boot_cpu().

Yeah, we can pick the current patch for the fixes and wait a better
solution is available later.

>
> Also a bit unrelated, but am I correct to assume that KVM_HINTS_DEDICATED
> can be
> used via qemu? I've only been dealing with kernel parameters.

The host admin can control it by qemu command-line, -cpu ...+kvm-hint-dedicated

Regards,
Wanpeng Li