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x86/litf: Introduce vmx status variable 

Store the effective mitigation of VMX in a status variable and use it to
report the VMX state in the l1tf sysfs file.

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/20180713142322.433098358@linutronix.de
This commit is contained in:
Thomas Gleixner 2018-07-13 16:23:16 +02:00
parent 215af5499d
commit 72c6d2db64
3 changed files with 54 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
arch/x86/include/asm/vmx.h
View File

@ -573,4 +573,13 @@ enum vm_instruction_error_number {
VMXERR_INVALID_OPERAND_TO_INVEPT_INVVPID = 28,
};
enum vmx_l1d_flush_state {
VMENTER_L1D_FLUSH_AUTO,
VMENTER_L1D_FLUSH_NEVER,
VMENTER_L1D_FLUSH_COND,
VMENTER_L1D_FLUSH_ALWAYS,
};
extern enum vmx_l1d_flush_state l1tf_vmx_mitigation;
#endif

36
arch/x86/kernel/cpu/bugs.c
View File

@ -22,6 +22,7 @@
#include <asm/processor-flags.h>
#include <asm/fpu/internal.h>
#include <asm/msr.h>
#include <asm/vmx.h>
#include <asm/paravirt.h>
#include <asm/alternative.h>
#include <asm/pgtable.h>
@ -657,6 +658,12 @@ void x86_spec_ctrl_setup_ap(void)
#undef pr_fmt
#define pr_fmt(fmt) "L1TF: " fmt
#if IS_ENABLED(CONFIG_KVM_INTEL)
enum vmx_l1d_flush_state l1tf_vmx_mitigation __ro_after_init = VMENTER_L1D_FLUSH_AUTO;
EXPORT_SYMBOL_GPL(l1tf_vmx_mitigation);
#endif
static void __init l1tf_select_mitigation(void)
{
u64 half_pa;
@ -686,6 +693,32 @@ static void __init l1tf_select_mitigation(void)
#ifdef CONFIG_SYSFS
#define L1TF_DEFAULT_MSG "Mitigation: PTE Inversion"
#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",
};
static ssize_t l1tf_show_state(char *buf)
{
if (l1tf_vmx_mitigation == VMENTER_L1D_FLUSH_AUTO)
return sprintf(buf, "%s\n", L1TF_DEFAULT_MSG);
return sprintf(buf, "%s; VMX: SMT %s, L1D %s\n", L1TF_DEFAULT_MSG,
cpu_smt_control == CPU_SMT_ENABLED ? "vulnerable" : "disabled",
l1tf_vmx_states[l1tf_vmx_mitigation]);
}
#else
static ssize_t l1tf_show_state(char *buf)
{
return sprintf(buf, "%s\n", L1TF_DEFAULT_MSG);
}
#endif
static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr,
char *buf, unsigned int bug)
{
@ -713,9 +746,8 @@ static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr
case X86_BUG_L1TF:
if (boot_cpu_has(X86_FEATURE_L1TF_PTEINV))
return sprintf(buf, "Mitigation: Page Table Inversion\n");
return l1tf_show_state(buf);
break;
default:
break;
}

22
arch/x86/kvm/vmx.c
View File

@ -193,19 +193,13 @@ 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[] = {
{"auto", VMENTER_L1D_FLUSH_AUTO},
{"never", VMENTER_L1D_FLUSH_NEVER},
{"cond", VMENTER_L1D_FLUSH_COND},
{"always", VMENTER_L1D_FLUSH_ALWAYS},
@ -13235,8 +13229,12 @@ static int __init vmx_setup_l1d_flush(void)
{
struct page *page;
if (!boot_cpu_has_bug(X86_BUG_L1TF))
return 0;
l1tf_vmx_mitigation = vmentry_l1d_flush;
if (vmentry_l1d_flush == VMENTER_L1D_FLUSH_NEVER ||
!boot_cpu_has_bug(X86_BUG_L1TF) ||
vmx_l1d_use_msr_save_list())
return 0;
@ -13251,12 +13249,14 @@ static int __init vmx_setup_l1d_flush(void)
return 0;
}
static void vmx_free_l1d_flush_pages(void)
static void vmx_cleanup_l1d_flush(void)
{
if (vmx_l1d_flush_pages) {
free_pages((unsigned long)vmx_l1d_flush_pages, L1D_CACHE_ORDER);
vmx_l1d_flush_pages = NULL;
}
/* Restore state so sysfs ignores VMX */
l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_AUTO;
}
static int __init vmx_init(void)
@ -13299,7 +13299,7 @@ static int __init vmx_init(void)
r = kvm_init(&vmx_x86_ops, sizeof(struct vcpu_vmx),
__alignof__(struct vcpu_vmx), THIS_MODULE);
if (r) {
vmx_free_l1d_flush_pages();
vmx_cleanup_l1d_flush();
return r;
}
@ -13343,7 +13343,7 @@ static void __exit vmx_exit(void)
static_branch_disable(&enable_evmcs);
}
#endif
vmx_free_l1d_flush_pages();
vmx_cleanup_l1d_flush();
}
module_init(vmx_init)