linux-kernel - Re: [PATCH v2 3/6] x86/kvm: introduce per cpu vcpu masks

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Message-ID: <20210903160503.htkifa5g5wobte5b@habkost.net>
Date:   Fri, 3 Sep 2021 12:05:03 -0400
From:   Eduardo Habkost <ehabkost@...hat.com>
To:     Juergen Gross <jgross@...e.com>
Cc:     kvm@...r.kernel.org, x86@...nel.org, linux-kernel@...r.kernel.org,
        maz@...nel.org, Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH v2 3/6] x86/kvm: introduce per cpu vcpu masks

On Fri, Sep 03, 2021 at 03:08:04PM +0200, Juergen Gross wrote:
> In order to support high vcpu numbers per guest don't use on stack
> vcpu bitmasks. As all those currently used bitmasks are not used in
> functions subject to recursion it is fairly easy to replace them with
> percpu bitmasks.
> 
> Disable preemption while such a bitmask is being used in order to
> avoid double usage in case we'd switch cpus.
> 
> Signed-off-by: Juergen Gross <jgross@...e.com>

Note that there's another patch that will introduce another
KVM_MAX_VCPUS bitmap variable on the stack:
https://lore.kernel.org/lkml/20210827092516.1027264-7-vkuznets@redhat.com/

Considering that the patch is a bug fix, should this series be
rebased on top of that?

-- 
Eduardo