linux-kernel - [PATCH v5 11/30] KVM: Add arch hook for reboot event

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Message-Id: <61dcd6722743bf221f6c612e120a9e2350d5a72f.1663869838.git.isaku.yamahata@intel.com>
Date:   Thu, 22 Sep 2022 11:20:40 -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 11/30] KVM: Add arch hook for reboot event

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

Factor out the logic on reboot event as arch hook.  Later kvm/x86 overrides
it.

Suggested-by: Sean Christopherson <seanjc@...gle.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
---
 include/linux/kvm_host.h |  2 ++
 virt/kvm/kvm_main.c      | 18 ++++++++++++++++--
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 3fbb01bbac98..084ee8a13e9f 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1434,6 +1434,8 @@ void kvm_arch_create_vcpu_debugfs(struct kvm_vcpu *vcpu, struct dentry *debugfs_
 static inline void kvm_create_vcpu_debugfs(struct kvm_vcpu *vcpu) {}
 #endif
 
+int kvm_arch_reboot(int val);
+
 int kvm_arch_hardware_enable(void);
 void kvm_arch_hardware_disable(void);
 int kvm_arch_hardware_setup(void *opaque);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index e2c8823786ff..58385000b73f 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1142,6 +1142,12 @@ int __weak kvm_arch_del_vm(int usage_count)
 	return 0;
 }
 
+int __weak kvm_arch_reboot(int val)
+{
+	on_each_cpu(hardware_disable_nolock, NULL, 1);
+	return NOTIFY_OK;
+}
+
 /*
  * Called just after removing the VM from the vm_list, but before doing any
  * other destruction.
@@ -5135,6 +5141,8 @@ static void kvm_del_vm(void)
 static int kvm_reboot(struct notifier_block *notifier, unsigned long val,
 		      void *v)
 {
+	int r;
+
 	/*
 	 * Some (well, at least mine) BIOSes hang on reboot if
 	 * in vmx root mode.
@@ -5143,8 +5151,14 @@ static int kvm_reboot(struct notifier_block *notifier, unsigned long val,
 	 */
 	pr_info("kvm: exiting hardware virtualization\n");
 	kvm_rebooting = true;
-	on_each_cpu(hardware_disable_nolock, NULL, 1);
-	return NOTIFY_OK;
+
+	/* This hook is called without cpuhotplug disabled.  */
+	cpus_read_lock();
+	mutex_lock(&kvm_lock);
+	r = kvm_arch_reboot(val);
+	mutex_unlock(&kvm_lock);
+	cpus_read_unlock();
+	return r;
 }
 
 static struct notifier_block kvm_reboot_notifier = {
-- 
2.25.1