diff options
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 6 | ||||
| -rw-r--r-- | arch/x86/kvm/vmx.c | 13 | ||||
| -rw-r--r-- | kernel/cpu.c | 1 |
3 files changed, 20 insertions, 0 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 5da7b0b30432..298f1b38dc89 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1946,6 +1946,12 @@ [KVM,ARM] Allow use of GICv4 for direct injection of LPIs. + kvm-intel.nosmt=[KVM,Intel] If the L1TF CPU bug is present (CVE-2018-3620) + and the system has SMT (aka Hyper-Threading) enabled then + don't allow guests to be created. + + Default is 0 (allow guests to be created). + kvm-intel.ept= [KVM,Intel] Disable extended page tables (virtualized MMU) support on capable Intel chips. Default is 1 (enabled) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 559a12b6184d..f2e7b6d016c9 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -71,6 +71,9 @@ static const struct x86_cpu_id vmx_cpu_id[] = { }; MODULE_DEVICE_TABLE(x86cpu, vmx_cpu_id); +static bool __read_mostly nosmt; +module_param(nosmt, bool, S_IRUGO); + static bool __read_mostly enable_vpid = 1; module_param_named(vpid, enable_vpid, bool, 0444); @@ -10370,10 +10373,20 @@ free_vcpu: return ERR_PTR(err); } +#define L1TF_MSG "SMT enabled with L1TF CPU bug present. Refer to CVE-2018-3620 for details.\n" + static int vmx_vm_init(struct kvm *kvm) { if (!ple_gap) kvm->arch.pause_in_guest = true; + + if (boot_cpu_has(X86_BUG_L1TF) && cpu_smt_control == CPU_SMT_ENABLED) { + if (nosmt) { + pr_err(L1TF_MSG); + return -EOPNOTSUPP; + } + pr_warn(L1TF_MSG); + } return 0; } diff --git a/kernel/cpu.c b/kernel/cpu.c index 6f3a3cde8b83..5a00ebdf98c6 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -345,6 +345,7 @@ EXPORT_SYMBOL_GPL(cpu_hotplug_enable); #ifdef CONFIG_HOTPLUG_SMT enum cpuhp_smt_control cpu_smt_control __read_mostly = CPU_SMT_ENABLED; +EXPORT_SYMBOL_GPL(cpu_smt_control); static int __init smt_cmdline_disable(char *str) { |