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Date:   Fri, 9 Sep 2022 13:48:32 +0800
From:   Chao Gao <chao.gao@intel.com>
To:     <isaku.yamahata@intel.com>
CC:     <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 12/26] KVM: x86: Move TSC fixup logic to KVM arch
 resume callback
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References: <cover.1662679124.git.isaku.yamahata@intel.com>
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On Thu, Sep 08, 2022 at 04:25:28PM -0700, isaku.yamahata@intel.com wrote:
>From: Isaku Yamahata <isaku.yamahata@intel.com>
>
>commit 0dd6a6edb012 ("KVM: Dont mark TSC unstable due to S4 suspend") made
>use of kvm_arch_hardware_enable() callback to detect that TSC goes backward
>due to S4 suspend.  It has to check it only when resuming from S4. Not
>every time virtualization hardware ennoblement.  Move the logic to
>kvm_arch_resume() callback.

IIUC, kvm_arch_resume() is called on the first CPU waking up from suspension.
But the detection was done on every CPU. Is it a problem (i.e., we fail to
detect TSC goes backward on some CPUs)?