linux-kernel - [PATCH v3] KVM: Check the allocation of pv cpu mask

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Date:   Sat, 26 Sep 2020 02:07:38 +0800
From:   lihaiwei.kernel@...il.com
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org, x86@...nel.org
Cc:     pbonzini@...hat.com, sean.j.christopherson@...el.com,
        vkuznets@...hat.com, wanpengli@...cent.com, jmattson@...gle.com,
        joro@...tes.org, tglx@...utronix.de, mingo@...hat.com,
        bp@...en8.de, hpa@...or.com, Haiwei Li <lihaiwei@...cent.com>
Subject: [PATCH v3] KVM: Check the allocation of pv cpu mask

From: Haiwei Li <lihaiwei@...cent.com>

check the allocation of per-cpu __pv_cpu_mask.

Suggested-by: Vitaly Kuznetsov <vkuznets@...hat.com>
Signed-off-by: Haiwei Li <lihaiwei@...cent.com>
---
v1 -> v2:
 * add CONFIG_SMP for kvm_send_ipi_mask_allbutself to prevent build error
v2 -> v3:
 * always check the allocation of __pv_cpu_mask in kvm_flush_tlb_others

 arch/x86/kernel/kvm.c | 27 ++++++++++++++++++++++++---
 1 file changed, 24 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 9663ba31347c..1e5da6db519c 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -553,7 +553,6 @@ static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, int vector)
 static void kvm_setup_pv_ipi(void)
 {
 	apic->send_IPI_mask = kvm_send_ipi_mask;
-	apic->send_IPI_mask_allbutself = kvm_send_ipi_mask_allbutself;
 	pr_info("setup PV IPIs\n");
 }
 
@@ -619,6 +618,11 @@ static void kvm_flush_tlb_others(const struct cpumask *cpumask,
 	struct kvm_steal_time *src;
 	struct cpumask *flushmask = this_cpu_cpumask_var_ptr(__pv_cpu_mask);
 
+	if (unlikely(!flushmask)) {
+		native_flush_tlb_others(cpumask, info);
+		return;
+	}
+
 	cpumask_copy(flushmask, cpumask);
 	/*
 	 * We have to call flush only on online vCPUs. And
@@ -765,6 +769,14 @@ static __init int activate_jump_labels(void)
 }
 arch_initcall(activate_jump_labels);
 
+static void kvm_free_cpumask(void)
+{
+	unsigned int cpu;
+
+	for_each_possible_cpu(cpu)
+		free_cpumask_var(per_cpu(__pv_cpu_mask, cpu));
+}
+
 static __init int kvm_alloc_cpumask(void)
 {
 	int cpu;
@@ -783,11 +795,20 @@ static __init int kvm_alloc_cpumask(void)
 
 	if (alloc)
 		for_each_possible_cpu(cpu) {
-			zalloc_cpumask_var_node(per_cpu_ptr(&__pv_cpu_mask, cpu),
-				GFP_KERNEL, cpu_to_node(cpu));
+			if (!zalloc_cpumask_var_node(
+				per_cpu_ptr(&__pv_cpu_mask, cpu),
+				GFP_KERNEL, cpu_to_node(cpu)))
+				goto zalloc_cpumask_fail;
 		}
 
+#if defined(CONFIG_SMP)
+	apic->send_IPI_mask_allbutself = kvm_send_ipi_mask_allbutself;
+#endif
 	return 0;
+
+zalloc_cpumask_fail:
+	kvm_free_cpumask();
+	return -ENOMEM;
 }
 arch_initcall(kvm_alloc_cpumask);
 
-- 
2.18.4