From: Sean Christopherson <seanjc@google.com>
To: Chao Gao <chao.gao@intel.com>
Cc: maz@kernel.org, kvm@vger.kernel.org, pbonzini@redhat.com,
kevin.tian@intel.com, tglx@linutronix.de,
John Garry <john.garry@huawei.com>, Will Deacon <will@kernel.org>,
Shaokun Zhang <zhangshaokun@hisilicon.com>,
Qi Liu <liuqi115@huawei.com>,
Sumanth Korikkar <sumanthk@linux.ibm.com>,
Thomas Richter <tmricht@linux.ibm.com>,
Dave Chinner <dchinner@redhat.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 5/6] KVM: Rename and move CPUHP_AP_KVM_STARTING to ONLINE section
Date: Fri, 18 Feb 2022 18:34:44 +0000 [thread overview]
Message-ID: <Yg/mxKrB5ZoRBIG+@google.com> (raw)
In-Reply-To: <20220216031528.92558-6-chao.gao@intel.com>
On Wed, Feb 16, 2022, Chao Gao wrote:
> The CPU STARTING section doesn't allow callbacks to fail. Move KVM's
> hotplug callback to ONLINE section so that it can abort onlining a CPU in
> certain cases to avoid potentially breaking VMs running on existing CPUs.
> For example, when kvm fails to enable hardware virtualization on the
> hotplugged CPU.
>
> Place KVM's hotplug state before CPUHP_AP_SCHED_WAIT_EMPTY as it ensures
> when offlining a CPU, all user tasks and non-pinned kernel tasks have left
> the CPU, i.e. there cannot be a vCPU task around. So, it is safe for KVM's
> CPU offline callback to disable hardware virtualization at that point.
> Likewise, KVM's online callback can enable hardware virtualization before
> any vCPU task gets a chance to run on hotplugged CPUs.
>
> KVM's CPU hotplug callbacks are renamed as well.
>
> Suggested-by: Thomas Gleixner <tglx@linutronix.de>
> Signed-off-by: Chao Gao <chao.gao@intel.com>
> ---
For the KVM bits,
Reviewed-by: Sean Christopherson <seanjc@google.com>
Someone with more knowledge of the CPU hotplug sequences should really review this
too.
next prev parent reply other threads:[~2022-02-18 18:34 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-16 3:15 [PATCH v4 0/6] Improve KVM's interaction with CPU hotplug Chao Gao
2022-02-16 3:15 ` Chao Gao
2022-02-16 3:15 ` Chao Gao
2022-02-16 3:15 ` [PATCH v4 1/6] KVM: x86: Move check_processor_compatibility from init ops to runtime ops Chao Gao
2022-02-16 3:15 ` [PATCH v4 2/6] Partially revert "KVM: Pass kvm_init()'s opaque param to additional arch funcs" Chao Gao
2022-02-16 3:15 ` Chao Gao
2022-02-16 3:15 ` Chao Gao
2022-02-16 3:25 ` Anup Patel
2022-02-16 3:25 ` Anup Patel
2022-02-16 3:25 ` Anup Patel
2022-02-16 16:21 ` Claudio Imbrenda
2022-02-16 16:21 ` Claudio Imbrenda
2022-02-16 16:21 ` Claudio Imbrenda
2022-02-16 16:21 ` Claudio Imbrenda
2022-03-17 13:24 ` Suzuki Kuruppassery Poulose
2022-03-17 13:24 ` Suzuki Kuruppassery Poulose
2022-03-17 13:24 ` Suzuki Kuruppassery Poulose
2022-03-17 13:24 ` Suzuki Kuruppassery Poulose
2022-02-16 3:15 ` [PATCH v4 3/6] KVM: Provide more information in kernel log if hardware enabling fails Chao Gao
2022-02-16 3:15 ` [PATCH v4 4/6] KVM: arm64: Simplify the CPUHP logic Chao Gao
2022-02-16 3:15 ` Chao Gao
2022-03-17 17:36 ` Oliver Upton
2022-03-17 17:36 ` Oliver Upton
2022-03-17 17:36 ` Oliver Upton
2022-02-16 3:15 ` [PATCH v4 5/6] KVM: Rename and move CPUHP_AP_KVM_STARTING to ONLINE section Chao Gao
2022-02-18 18:34 ` Sean Christopherson [this message]
2022-02-16 3:15 ` [PATCH v4 6/6] KVM: Do compatibility checks on hotplugged CPUs Chao Gao
2022-03-17 9:15 ` [PATCH v4 0/6] Improve KVM's interaction with CPU hotplug Chao Gao
2022-03-17 9:15 ` Chao Gao
2022-03-17 9:15 ` Chao Gao
2022-03-17 9:15 ` Chao Gao
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