linux-kernel - Re: [PATCH] x86/kvm: Don't alloc __pv_cpu_mask when !CONFIG

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Message-ID: <CANRm+Cx-tfomRgV-QbyfvZZ7g7HBskm+p97zifUS8C0bdZyR8w@mail.gmail.com>
Date:   Fri, 9 Apr 2021 11:03:00 +0800
From:   Wanpeng Li <kernellwp@...il.com>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     LKML <linux-kernel@...r.kernel.org>, kvm <kvm@...r.kernel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>
Subject: Re: [PATCH] x86/kvm: Don't alloc __pv_cpu_mask when !CONFIG_SMP

On Fri, 9 Apr 2021 at 04:20, Sean Christopherson <seanjc@...gle.com> wrote:
>
> On Wed, Apr 07, 2021, Wanpeng Li wrote:
> > From: Wanpeng Li <wanpengli@...cent.com>
> >
> > Enable PV TLB shootdown when !CONFIG_SMP doesn't make sense. Let's move
> > it inside CONFIG_SMP. In addition, we can avoid alloc __pv_cpu_mask when
> > !CONFIG_SMP and get rid of 'alloc' variable in kvm_alloc_cpumask.
>
> ...
>
> > +static bool pv_tlb_flush_supported(void) { return false; }
> > +static bool pv_ipi_supported(void) { return false; }
> > +static void kvm_flush_tlb_others(const struct cpumask *cpumask,
> > +                     const struct flush_tlb_info *info) { }
> > +static void kvm_setup_pv_ipi(void) { }
>
> If you shuffle things around a bit more, you can avoid these stubs, and hide the
> definition of __pv_cpu_mask behind CONFIG_SMP, too.

Thanks, I will move around.

    Wanpeng