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Date:   Sat, 10 Sep 2022 19:50:56 -0700
From:   Isaku Yamahata <isaku.yamahata@gmail.com>
To:     Chao Gao <chao.gao@intel.com>
Cc:     isaku.yamahata@intel.com, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>,
        Sean Christopherson <seanjc@google.com>,
        Marc Zyngier <maz@kernel.org>, Will Deacon <will@kernel.org>,
        Yuan Yao <yuan.yao@linux.intel.com>, isaku.yamahata@gmail.com,
        Kai Huang <kai.huang@intel.com>,
        Atish Patra <atishp@atishpatra.org>,
        Shaokun Zhang <zhangshaokun@hisilicon.com>,
        Qi Liu <liuqi115@huawei.com>,
        John Garry <john.garry@huawei.com>,
        Daniel Lezcano <daniel.lezcano@linaro.org>,
        Huang Ying <ying.huang@intel.com>,
        Huacai Chen <chenhuacai@kernel.org>
Subject: Re: [PATCH v4 13/26] KVM: Add arch hook when VM is added/deleted
Message-ID: <20220911025056.GA873583@ls.amr.corp.intel.com>
References: <cover.1662679124.git.isaku.yamahata@intel.com>
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 <YxrYRKeU/AfCVJFO@gao-cwp>
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On Fri, Sep 09, 2022 at 02:08:04PM +0800,
Chao Gao <chao.gao@intel.com> wrote:

> >+static void kvm_del_vm(void)
> >+{
> >+	cpus_read_lock();
> >+	mutex_lock(&kvm_lock);
> >+	kvm_arch_del_vm(kvm_usage_count);
> >+	mutex_unlock(&kvm_lock);
> >+	cpus_read_unlock();
> 
> kvm_arch_del_vm() is an empty function now. I don't understand why
> cpus_read_lock() is needed. Maybe add the lock when you fill up
> kvm_arch_del_vm().

The next patch populates it with on_each_cpu(hardware_disable_nolock, NULL, 1);
I will move adding lock to the next one. Or revise how adding arch hooks and
populating part.
-- 
Isaku Yamahata <isaku.yamahata@gmail.com>