linux-kernel - [PATCH v5 16/30] KVM: Remove on_each_cpu(hardware_disable_nolock) in kvm

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Date:   Thu, 22 Sep 2022 11:20:45 -0700
From:   isaku.yamahata@...el.com
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <maz@...nel.org>, Will Deacon <will@...nel.org>
Cc:     isaku.yamahata@...el.com, isaku.yamahata@...il.com,
        Kai Huang <kai.huang@...el.com>, Chao Gao <chao.gao@...el.com>,
        Atish Patra <atishp@...shpatra.org>,
        Shaokun Zhang <zhangshaokun@...ilicon.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Huang Ying <ying.huang@...el.com>,
        Huacai Chen <chenhuacai@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Borislav Petkov <bp@...en8.de>
Subject: [PATCH v5 16/30] KVM: Remove on_each_cpu(hardware_disable_nolock) in kvm_exit()

From: Isaku Yamahata <isaku.yamahata@...el.com>

hardware_enable/disable_nolock() check if the hardware is already
enabled/disabled and work as nop when they are called multiple times.

When VM is created/destroyed, on_each_cpu(hardware_enable/disable_nolock)
via kvm_arch_add/del_vm() and module_get/put() are called.  It means when
kvm module is removed, it's guaranteed that there is no vm and that
hardware_disable_nolock() was called on each cpus.

Although the module exit function, kvm_exit(), calls
on_each_cpu(hardware_disable_nolock), it's essentially nop.  Eliminate nop
call in kvm_exit().

Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
---
 virt/kvm/kvm_main.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index ad9b8b7d21fa..d7c3bc14691f 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -6034,7 +6034,6 @@ void kvm_exit(void)
 	unregister_syscore_ops(&kvm_syscore_ops);
 	unregister_reboot_notifier(&kvm_reboot_notifier);
 	cpuhp_remove_state_nocalls(CPUHP_AP_KVM_ONLINE);
-	on_each_cpu(hardware_disable_nolock, NULL, 1);
 	kvm_arch_hardware_unsetup();
 	kvm_arch_exit();
 	kvm_irqfd_exit();
-- 
2.25.1