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From:   isaku.yamahata@intel.com
To:     linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
        Paolo Bonzini <pbonzini@redhat.com>,
        Sean Christopherson <seanjc@google.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Marc Zyngier <maz@kernel.org>, Will Deacon <will@kernel.org>
Cc:     isaku.yamahata@intel.com, isaku.yamahata@gmail.com,
        Kai Huang <kai.huang@intel.com>, Chao Gao <chao.gao@intel.com>,
        Atish Patra <atishp@atishpatra.org>,
        Shaokun Zhang <zhangshaokun@hisilicon.com>,
        Daniel Lezcano <daniel.lezcano@linaro.org>,
        Huang Ying <ying.huang@intel.com>,
        Huacai Chen <chenhuacai@kernel.org>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Borislav Petkov <bp@alien8.de>
Subject: [PATCH v5 15/30] KVM: Add arch hook for cpu offline event
Date:   Thu, 22 Sep 2022 11:20:44 -0700
Message-Id: <1bed181569380dfa3c7bc5c6b3f0acc1de01217e.1663869838.git.isaku.yamahata@intel.com>
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From: Isaku Yamahata <isaku.yamahata@intel.com>

Factor out the logic on cpu offline event as arch callback.  Later kvm/x86
will override it.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
---
 include/linux/kvm_host.h |  1 +
 virt/kvm/kvm_main.c      | 30 +++++++++++++++++++-----------
 2 files changed, 20 insertions(+), 11 deletions(-)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 013b33a19030..f3a79d55ca8c 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1435,6 +1435,7 @@ static inline void kvm_create_vcpu_debugfs(struct kvm_vcpu *vcpu) {}
 #endif
 
 int kvm_arch_online_cpu(unsigned int cpu, int usage_count);
+int kvm_arch_offline_cpu(unsigned int cpu, int usage_count);
 int kvm_arch_reboot(int val);
 int kvm_arch_suspend(int usage_count);
 void kvm_arch_resume(int usage_count);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 4c535ae412a7..ad9b8b7d21fa 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1174,6 +1174,21 @@ int __weak kvm_arch_online_cpu(unsigned int cpu, int usage_count)
 	return ret;
 }
 
+int __weak kvm_arch_offline_cpu(unsigned int cpu, int usage_count)
+{
+	if (usage_count) {
+		/*
+		 * arch callback kvm_arch_hardware_disable() assumes that
+		 * preemption is disabled for historical reason.  Disable
+		 * preemption until all arch callbacks are fixed.
+		 */
+		preempt_disable();
+		hardware_disable_nolock(NULL);
+		preempt_enable();
+	}
+	return 0;
+}
+
 int __weak kvm_arch_reboot(int val)
 {
 	on_each_cpu(hardware_disable_nolock, NULL, 1);
@@ -5137,19 +5152,12 @@ static void hardware_disable_nolock(void *junk)
 
 static int kvm_offline_cpu(unsigned int cpu)
 {
+	int ret;
+
 	mutex_lock(&kvm_lock);
-	if (kvm_usage_count) {
-		/*
-		 * arch callback kvm_arch_hardware_disable() assumes that
-		 * preemption is disabled for historical reason.  Disable
-		 * preemption until all arch callbacks are fixed.
-		 */
-		preempt_disable();
-		hardware_disable_nolock(NULL);
-		preempt_enable();
-	}
+	ret = kvm_arch_offline_cpu(cpu, kvm_usage_count);
 	mutex_unlock(&kvm_lock);
-	return 0;
+	return ret;
 }
 
 static void kvm_del_vm(void)
-- 
2.25.1