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Commit 72c6d2db authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

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: default avatarThomas Gleixner <tglx@linutronix.de>
Tested-by: default avatarJiri Kosina <jkosina@suse.cz>
Reviewed-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20180713142322.433098358@linutronix.de
parent 215af549

arch/x86/include/asm/vmx.h

+9 −0
Original line number Diff line number Diff line
@@ -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

arch/x86/kernel/cpu/bugs.c

+34 −2
Original line number Diff line number Diff line
@@ -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;

	}

arch/x86/kvm/vmx.c

+11 −11
Original line number Diff line number Diff line
@@ -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)