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 12/26] KVM: x86: Move TSC fixup logic to KVM arch resume callback
Date: Sat, 10 Sep 2022 19:45:45 -0700 [thread overview]
Message-ID: <20220911024545.GE699006@ls.amr.corp.intel.com> (raw)
In-Reply-To: <YxrTsE8iT6mTCZgg@gao-cwp>
On Fri, Sep 09, 2022 at 01:48:32PM +0800,
Chao Gao <chao.gao@intel.com> wrote:
> 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)?
The problem is, TSC fixup logic is only needed once on resuming.
The current code calls TSC fixup logic on each cpu onlining. It's quick
plumbing the logic to each cpu online. Although it won't harm to call the logic,
it's ugly and this time is good occasion to clean it up.
I will clarify the commit message.
--
Isaku Yamahata <isaku.yamahata@gmail.com>
next prev parent reply other threads:[~2022-09-11 2:45 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-08 23:25 [PATCH v4 00/26] KVM: hardware enable/disable reorganize isaku.yamahata
2022-09-08 23:25 ` [PATCH v4 01/26] KVM: x86: Drop kvm_user_return_msr_cpu_online() isaku.yamahata
2022-09-08 23:25 ` [PATCH v4 02/26] KVM: x86: Use this_cpu_ptr() instead of per_cpu_ptr(smp_processor_id()) isaku.yamahata
2022-09-08 23:25 ` [PATCH v4 03/26] KVM: x86: Move check_processor_compatibility from init ops to runtime ops isaku.yamahata
2022-09-08 23:25 ` [PATCH v4 04/26] Partially revert "KVM: Pass kvm_init()'s opaque param to additional arch funcs" isaku.yamahata
2022-09-08 23:25 ` [PATCH v4 05/26] KVM: Provide more information in kernel log if hardware enabling fails isaku.yamahata
2022-09-08 23:25 ` [PATCH v4 06/26] KVM: arm64: Simplify the CPUHP logic isaku.yamahata
2022-09-12 15:07 ` Marc Zyngier
2022-09-08 23:25 ` [PATCH v4 07/26] KVM: Rename and move CPUHP_AP_KVM_STARTING to ONLINE section isaku.yamahata
2022-09-08 23:25 ` [PATCH v4 08/26] KVM: Do compatibility checks on hotplugged CPUs isaku.yamahata
2022-09-08 23:25 ` [PATCH v4 09/26] KVM: Do processor compatibility check on resume isaku.yamahata
2022-09-09 2:15 ` Chao Gao
2022-09-10 17:59 ` Isaku Yamahata
2022-09-08 23:25 ` [PATCH v4 10/26] KVM: Drop kvm_count_lock and instead protect kvm_usage_count with kvm_lock isaku.yamahata
2022-09-09 3:05 ` Chao Gao
2022-09-10 18:11 ` Isaku Yamahata
2022-09-08 23:25 ` [PATCH v4 11/26] KVM: Add arch hooks for PM events with empty stub isaku.yamahata
2022-09-09 4:34 ` Chao Gao
2022-09-11 2:39 ` Isaku Yamahata
2022-09-08 23:25 ` [PATCH v4 12/26] KVM: x86: Move TSC fixup logic to KVM arch resume callback isaku.yamahata
2022-09-09 5:48 ` Chao Gao
2022-09-11 2:45 ` Isaku Yamahata [this message]
2022-09-08 23:25 ` [PATCH v4 13/26] KVM: Add arch hook when VM is added/deleted isaku.yamahata
2022-09-09 6:08 ` Chao Gao
2022-09-11 2:50 ` Isaku Yamahata
2022-09-08 23:25 ` [PATCH v4 14/26] KVM: Move out KVM arch PM hooks and hardware enable/disable logic isaku.yamahata
2022-09-08 23:25 ` [PATCH v4 15/26] KVM: kvm_arch.c: Remove _nolock post fix isaku.yamahata
2022-09-09 6:30 ` Chao Gao
2022-09-08 23:25 ` [PATCH v4 16/26] KVM: kvm_arch.c: Remove a global variable, hardware_enable_failed isaku.yamahata
2022-09-09 6:54 ` Chao Gao
2022-09-11 3:00 ` Isaku Yamahata
2022-09-08 23:25 ` [PATCH v4 17/26] KVM: Introduce a arch wrapper to check all processor compatibility isaku.yamahata
2022-09-09 7:32 ` Chao Gao
2022-09-08 23:25 ` [PATCH v4 18/26] KVM: x86: Duplicate arch callbacks related to pm events and compat check isaku.yamahata
2022-09-08 23:25 ` [PATCH v4 19/26] KVM: Eliminate kvm_arch_post_init_vm() isaku.yamahata
2022-09-08 23:25 ` [PATCH v4 20/26] KVM: Add config to not compile kvm_arch.c isaku.yamahata
2022-09-08 23:25 ` [PATCH v4 21/26] KVM: x86: Delete kvm_arch_hardware_enable/disable() isaku.yamahata
2022-09-08 23:25 ` [PATCH v4 22/26] KVM: x86: Make x86 processor compat check callback empty isaku.yamahata
2022-09-08 23:25 ` [PATCH v4 23/26] RFC: KVM: powerpc: Move processor compatibility check to hardware setup isaku.yamahata
2022-09-09 5:55 ` Christophe Leroy
2022-09-10 1:39 ` Isaku Yamahata
2022-09-08 23:25 ` [PATCH v4 24/26] KVM: Eliminate kvm_arch_check_processor_compat() isaku.yamahata
2022-09-08 23:25 ` [PATCH v4 25/26] RFC: KVM: x86: Remove cpus_hardware_enabled and related sanity check isaku.yamahata
2022-09-08 23:25 ` [PATCH v4 26/26] RFC: KVM: " isaku.yamahata
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