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x86/l1tf: Handle EPT disabled state proper

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If Extended Page Tables (EPT) are disabled or not supported, no L1D
flushing is required. The setup function can just avoid setting up the L1D
flush for the EPT=n case.

Invoke it after the hardware setup has be done and enable_ept has the
correct state and expose the EPT disabled state in the mitigation status as
well.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20180713142322.612160168@linutronix.de
This commit is contained in:
Thomas Gleixner 2018-07-13 16:23:18 +02:00
parent 2f055947ae
commit a7b9020b06
3 changed files with 54 additions and 45 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/x86/include/asm/vmx.h
View File

@ -578,6 +578,7 @@ enum vmx_l1d_flush_state {
VMENTER_L1D_FLUSH_NEVER,
VMENTER_L1D_FLUSH_COND,
VMENTER_L1D_FLUSH_ALWAYS,
VMENTER_L1D_FLUSH_EPT_DISABLED,
};
extern enum vmx_l1d_flush_state l1tf_vmx_mitigation;

9
arch/x86/kernel/cpu/bugs.c
View File

@ -697,10 +697,11 @@ static void __init l1tf_select_mitigation(void)
#if IS_ENABLED(CONFIG_KVM_INTEL)
static const char *l1tf_vmx_states[] = {
[VMENTER_L1D_FLUSH_AUTO] = "auto",
[VMENTER_L1D_FLUSH_NEVER] = "vulnerable",
[VMENTER_L1D_FLUSH_COND] = "conditional cache flushes",
[VMENTER_L1D_FLUSH_ALWAYS] = "cache flushes",
[VMENTER_L1D_FLUSH_AUTO] = "auto",
[VMENTER_L1D_FLUSH_NEVER] = "vulnerable",
[VMENTER_L1D_FLUSH_COND] = "conditional cache flushes",
[VMENTER_L1D_FLUSH_ALWAYS] = "cache flushes",
[VMENTER_L1D_FLUSH_EPT_DISABLED] = "EPT disabled",
};
static ssize_t l1tf_show_state(char *buf)

89
arch/x86/kvm/vmx.c
View File

@ -13204,6 +13204,11 @@ static int __init vmx_setup_l1d_flush(void)
if (!boot_cpu_has_bug(X86_BUG_L1TF))
return 0;
if (!enable_ept) {
l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_EPT_DISABLED;
return 0;
}
l1tf_vmx_mitigation = vmentry_l1d_flush;
if (vmentry_l1d_flush == VMENTER_L1D_FLUSH_NEVER)
@ -13230,6 +13235,41 @@ static void vmx_cleanup_l1d_flush(void)
l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_AUTO;
}
static void vmx_exit(void)
{
#ifdef CONFIG_KEXEC_CORE
RCU_INIT_POINTER(crash_vmclear_loaded_vmcss, NULL);
synchronize_rcu();
#endif
kvm_exit();
#if IS_ENABLED(CONFIG_HYPERV)
if (static_branch_unlikely(&enable_evmcs)) {
int cpu;
struct hv_vp_assist_page *vp_ap;
/*
* Reset everything to support using non-enlightened VMCS
* access later (e.g. when we reload the module with
* enlightened_vmcs=0)
*/
for_each_online_cpu(cpu) {
vp_ap = hv_get_vp_assist_page(cpu);
if (!vp_ap)
continue;
vp_ap->current_nested_vmcs = 0;
vp_ap->enlighten_vmentry = 0;
}
static_branch_disable(&enable_evmcs);
}
#endif
vmx_cleanup_l1d_flush();
}
module_exit(vmx_exit);
static int __init vmx_init(void)
{
int r;
@ -13263,14 +13303,17 @@ static int __init vmx_init(void)
}
#endif
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;
r = kvm_init(&vmx_x86_ops, sizeof(struct vcpu_vmx),
__alignof__(struct vcpu_vmx), THIS_MODULE);
/*
* Must be called after kvm_init() so enable_ept is properly set up
*/
r = vmx_setup_l1d_flush();
if (r) {
vmx_cleanup_l1d_flush();
vmx_exit();
return r;
}
@ -13282,40 +13325,4 @@ static int __init vmx_init(void)
return 0;
}
static void __exit vmx_exit(void)
{
#ifdef CONFIG_KEXEC_CORE
RCU_INIT_POINTER(crash_vmclear_loaded_vmcss, NULL);
synchronize_rcu();
#endif
kvm_exit();
#if IS_ENABLED(CONFIG_HYPERV)
if (static_branch_unlikely(&enable_evmcs)) {
int cpu;
struct hv_vp_assist_page *vp_ap;
/*
* Reset everything to support using non-enlightened VMCS
* access later (e.g. when we reload the module with
* enlightened_vmcs=0)
*/
for_each_online_cpu(cpu) {
vp_ap = hv_get_vp_assist_page(cpu);
if (!vp_ap)
continue;
vp_ap->current_nested_vmcs = 0;
vp_ap->enlighten_vmentry = 0;
}
static_branch_disable(&enable_evmcs);
}
#endif
vmx_cleanup_l1d_flush();
}
module_init(vmx_init)
module_exit(vmx_exit)
module_init(vmx_init);