From: Peter Zijlstra <peterz@infradead.org>
To: Like Xu <like.xu.linux@gmail.com>
Cc: Sean Christopherson <seanjc@google.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
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Ard Biesheuvel <ardb@kernel.org>
Subject: Re: [PATCH 00/15] perf: KVM: Fix, optimize, and clean up callbacks
Date: Fri, 27 Aug 2021 12:47:25 +0200 [thread overview]
Message-ID: <YSjCvbWE6sZ29dPr@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <3bd4955a-1219-20b0-058b-d23f1e30aa77@gmail.com>
On Fri, Aug 27, 2021 at 04:01:45PM +0800, Like Xu wrote:
> On 27/8/2021 3:44 pm, Peter Zijlstra wrote:
> > You just have to make sure all static_call() invocations that started
> > before unreg are finished before continuing with the unload.
> > synchronize_rcu() can help with that.
>
> Do you mean something like that:
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 64e310ff4f3a..e7d310af7509 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -8465,6 +8465,7 @@ void kvm_arch_exit(void)
> #endif
> kvm_lapic_exit();
> perf_unregister_guest_info_callbacks(&kvm_guest_cbs);
> + synchronize_rcu();
>
> if (!boot_cpu_has(X86_FEATURE_CONSTANT_TSC))
> cpufreq_unregister_notifier(&kvmclock_cpufreq_notifier_block,
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index e466fc8176e1..63ae56c5d133 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -6508,6 +6508,7 @@ EXPORT_SYMBOL_GPL(perf_register_guest_info_callbacks);
> int perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
> {
> perf_guest_cbs = NULL;
> + arch_perf_update_guest_cbs();
I'm thinking the synchronize_rcu() should go here, and access to
perf_guest_cbs should be wrapped to yell when called with preemption
enabled.
But yes..
> return 0;
> }
> EXPORT_SYMBOL_GPL(perf_unregister_guest_info_callbacks);
>
> >
> > This is module unload 101. Nothing specific to static_call().
> >
prev parent reply other threads:[~2021-08-27 10:52 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-27 0:57 [PATCH 00/15] perf: KVM: Fix, optimize, and clean up callbacks Sean Christopherson
2021-08-27 0:57 ` [PATCH 01/15] KVM: x86: Register perf callbacks after calling vendor's hardware_setup() Sean Christopherson
2021-08-27 0:57 ` [PATCH 02/15] KVM: x86: Register Processor Trace interrupt hook iff PT enabled in guest Sean Christopherson
2021-08-27 0:57 ` [PATCH 03/15] perf: Stop pretending that perf can handle multiple guest callbacks Sean Christopherson
2021-08-27 0:57 ` [PATCH 04/15] perf: Force architectures to opt-in to " Sean Christopherson
2021-08-27 0:57 ` [PATCH 05/15] perf: Track guest callbacks on a per-CPU basis Sean Christopherson
2021-08-27 7:15 ` Peter Zijlstra
2021-08-27 14:49 ` Sean Christopherson
2021-08-27 14:56 ` Peter Zijlstra
2021-08-27 15:22 ` Sean Christopherson
2021-08-27 0:57 ` [PATCH 06/15] KVM: x86: Register perf callbacks only when actively handling interrupt Sean Christopherson
2021-08-27 7:21 ` Peter Zijlstra
2021-08-27 0:57 ` [PATCH 07/15] KVM: Use dedicated flag to track if KVM is handling an NMI from guest Sean Christopherson
2021-08-27 7:30 ` Peter Zijlstra
2021-08-27 14:58 ` Sean Christopherson
2021-08-27 0:57 ` [PATCH 08/15] KVM: x86: Drop current_vcpu in favor of kvm_running_vcpu Sean Christopherson
2021-08-27 0:57 ` [PATCH 09/15] KVM: arm64: Register/unregister perf callbacks at vcpu load/put Sean Christopherson
2021-08-27 0:57 ` [PATCH 10/15] KVM: Move x86's perf guest info callbacks to generic KVM Sean Christopherson
2021-08-27 0:57 ` [PATCH 11/15] KVM: x86: Move Intel Processor Trace interrupt handler to vmx.c Sean Christopherson
2021-08-27 7:34 ` Peter Zijlstra
2021-08-27 0:57 ` [PATCH 12/15] KVM: arm64: Convert to the generic perf callbacks Sean Christopherson
2021-08-27 0:57 ` [PATCH 13/15] KVM: arm64: Drop perf.c and fold its tiny bit of code into pmu.c Sean Christopherson
2021-08-27 0:57 ` [PATCH 14/15] perf: Disallow bulk unregistering of guest callbacks and do cleanup Sean Christopherson
2021-08-27 0:57 ` [PATCH 15/15] perf: KVM: Indicate "in guest" via NULL ->is_in_guest callback Sean Christopherson
2021-08-27 6:52 ` [PATCH 00/15] perf: KVM: Fix, optimize, and clean up callbacks Like Xu
2021-08-27 7:44 ` Peter Zijlstra
2021-08-27 8:01 ` Like Xu
2021-08-27 10:47 ` Peter Zijlstra [this message]
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