1 files changed, 63 insertions, 2 deletions

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index f43b6484ca2e..69122cf8bd1d 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -192,6 +192,54 @@ module_param(ple_window_max, int, S_IRUGO);
 
 extern const ulong vmx_return;
 
+static DEFINE_STATIC_KEY_FALSE(vmx_l1d_should_flush);
+
+/* These MUST be in sync with vmentry_l1d_param order. */
+enum vmx_l1d_flush_state {
+	VMENTER_L1D_FLUSH_NEVER,
+	VMENTER_L1D_FLUSH_COND,
+	VMENTER_L1D_FLUSH_ALWAYS,
+};
+
+static enum vmx_l1d_flush_state __read_mostly vmentry_l1d_flush = VMENTER_L1D_FLUSH_COND;
+
+static const struct {
+	const char *option;
+	enum vmx_l1d_flush_state cmd;
+} vmentry_l1d_param[] = {
+	{"never",	VMENTER_L1D_FLUSH_NEVER},
+	{"cond",	VMENTER_L1D_FLUSH_COND},
+	{"always",	VMENTER_L1D_FLUSH_ALWAYS},
+};
+
+static int vmentry_l1d_flush_set(const char *s, const struct kernel_param *kp)
+{
+	unsigned int i;
+
+	if (!s)
+		return -EINVAL;
+
+	for (i = 0; i < ARRAY_SIZE(vmentry_l1d_param); i++) {
+		if (!strcmp(s, vmentry_l1d_param[i].option)) {
+			vmentry_l1d_flush = vmentry_l1d_param[i].cmd;
+			return 0;
+		}
+	}
+
+	return -EINVAL;
+}
+
+static int vmentry_l1d_flush_get(char *s, const struct kernel_param *kp)
+{
+	return sprintf(s, "%s\n", vmentry_l1d_param[vmentry_l1d_flush].option);
+}
+
+static const struct kernel_param_ops vmentry_l1d_flush_ops = {
+	.set = vmentry_l1d_flush_set,
+	.get = vmentry_l1d_flush_get,
+};
+module_param_cb(vmentry_l1d_flush, &vmentry_l1d_flush_ops, &vmentry_l1d_flush, S_IRUGO);
+
 #define NR_AUTOLOAD_MSRS 8
 
 struct vmcs {
@@ -11505,10 +11553,23 @@ static struct kvm_x86_ops vmx_x86_ops __ro_after_init = {
 	.setup_mce = vmx_setup_mce,
 };
 
+static void __init vmx_setup_l1d_flush(void)
+{
+	if (vmentry_l1d_flush == VMENTER_L1D_FLUSH_NEVER ||
+	    !boot_cpu_has_bug(X86_BUG_L1TF))
+		return;
+
+	static_branch_enable(&vmx_l1d_should_flush);
+}
+
 static int __init vmx_init(void)
 {
-	int r = kvm_init(&vmx_x86_ops, sizeof(struct vcpu_vmx),
-                     __alignof__(struct vcpu_vmx), THIS_MODULE);
+	int r;
+
+	vmx_setup_l1d_flush();
+
+	r = kvm_init(&vmx_x86_ops, sizeof(struct vcpu_vmx),
+		     __alignof__(struct vcpu_vmx), THIS_MODULE);
 	if (r)
 		return r;