linux-kernel - [RFC PATCH 13/18] KVM: x86: Duplicate arch callbacks related to pm events

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Message-Id: <c1d64ba97ad4144e37a44b9d981e9bf8d8b8d755.1660974106.git.isaku.yamahata@intel.com>
Date:   Fri, 19 Aug 2022 23:00:19 -0700
From:   isaku.yamahata@...el.com
To:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     isaku.yamahata@...el.com, isaku.yamahata@...il.com,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Kai Huang <kai.huang@...el.com>, Chao Gao <chao.gao@...el.com>,
        Will Deacon <will@...nel.org>
Subject: [RFC PATCH 13/18] KVM: x86: Duplicate arch callbacks related to pm events

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

KVM/X86 can change those callbacks without worrying about breaking other
archs.

Suggested-by: Sean Christopherson <seanjc@...gle.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
---
 arch/x86/kvm/x86.c | 125 +++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 120 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 0b112cd7de58..71e90d0f0da9 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -11841,6 +11841,124 @@ void kvm_arch_hardware_disable(void)
 	drop_user_return_notifiers();
 }
 
+static cpumask_t cpus_hardware_enabled = CPU_MASK_NONE;
+
+int kvm_arch_post_init_vm(struct kvm *kvm)
+{
+	return kvm_mmu_post_init_vm(kvm);
+}
+
+static int __hardware_enable(void)
+{
+	int cpu = raw_smp_processor_id();
+	int r;
+
+	WARN_ON_ONCE(preemptible());
+
+	if (cpumask_test_cpu(cpu, &cpus_hardware_enabled))
+		return 0;
+	r = kvm_arch_hardware_enable();
+	if (r)
+		pr_info("kvm: enabling virtualization on CPU%d failed\n", cpu);
+	else
+		cpumask_set_cpu(cpu, &cpus_hardware_enabled);
+	return r;
+}
+
+static void hardware_enable(void *arg)
+{
+	atomic_t *failed = arg;
+
+	if (__hardware_enable())
+		atomic_inc(failed);
+}
+
+static void hardware_disable(void *junk)
+{
+	int cpu = raw_smp_processor_id();
+
+	WARN_ON_ONCE(preemptible());
+
+	if (!cpumask_test_cpu(cpu, &cpus_hardware_enabled))
+		return;
+	cpumask_clear_cpu(cpu, &cpus_hardware_enabled);
+	kvm_arch_hardware_disable();
+}
+
+void kvm_arch_pre_hardware_unsetup(void)
+{
+	on_each_cpu(hardware_disable, NULL, 1);
+}
+
+/*
+ * Called after the VM is otherwise initialized, but just before adding it to
+ * the vm_list.
+ */
+int kvm_arch_add_vm(struct kvm *kvm, int usage_count)
+{
+	atomic_t failed;
+	int r = 0;
+
+	if (usage_count != 1)
+		return 0;
+
+	atomic_set(&failed, 0);
+	on_each_cpu(hardware_enable, &failed, 1);
+
+	if (atomic_read(&failed)) {
+		r = -EBUSY;
+		goto err;
+	}
+
+	r = kvm_arch_post_init_vm(kvm);
+err:
+	if (r && usage_count == 1)
+		on_each_cpu(hardware_disable, NULL, 1);
+	return r;
+}
+
+int kvm_arch_del_vm(int usage_count)
+{
+	if (usage_count)
+		return 0;
+
+	on_each_cpu(hardware_disable, NULL, 1);
+	return 0;
+}
+
+int kvm_arch_online_cpu(unsigned int cpu, int usage_count)
+{
+	int r;
+
+	if (!usage_count)
+		return 0;
+
+	r = kvm_arch_check_processor_compat();
+	if (r)
+		return r;
+	return __hardware_enable();
+}
+
+int kvm_arch_offline_cpu(unsigned int cpu, int usage_count)
+{
+	if (usage_count)
+		hardware_disable(NULL);
+	return 0;
+}
+
+int kvm_arch_reboot(int val)
+{
+	on_each_cpu(hardware_disable, NULL, 1);
+	return NOTIFY_OK;
+}
+
+int kvm_arch_suspend(int usage_count)
+{
+	if (usage_count)
+		hardware_disable(NULL);
+	return 0;
+}
+
 void kvm_arch_resume(int usage_count)
 {
 	struct kvm *kvm;
@@ -11853,6 +11971,8 @@ void kvm_arch_resume(int usage_count)
 	if (!usage_count)
 		return;
 
+	if (kvm_arch_check_processor_compat())
+		return;
 	if (kvm_arch_hardware_enable())
 		return;
 
@@ -12104,11 +12224,6 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 	return ret;
 }
 
-int kvm_arch_post_init_vm(struct kvm *kvm)
-{
-	return kvm_mmu_post_init_vm(kvm);
-}
-
 static void kvm_unload_vcpu_mmu(struct kvm_vcpu *vcpu)
 {
 	vcpu_load(vcpu);
-- 
2.25.1