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Commit 895ae47f authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

x86/kvm: Allow runtime control of L1D flush 



All mitigation modes can be switched at run time with a static key now:

 - Use sysfs_streq() instead of strcmp() to handle the trailing new line
   from sysfs writes correctly.
 - Make the static key management handle multiple invocations properly.
 - Set the module parameter file to RW

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/20180713142322.954525119@linutronix.de
parent dd4bfa73

arch/x86/kernel/cpu/bugs.c

+1 −1
Original line number Diff line number Diff line
@@ -660,7 +660,7 @@ void x86_spec_ctrl_setup_ap(void) 
#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;

enum vmx_l1d_flush_state l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_AUTO;

EXPORT_SYMBOL_GPL(l1tf_vmx_mitigation);

#endif

arch/x86/kvm/vmx.c

+8 −5
Original line number Diff line number Diff line
@@ -234,12 +234,15 @@ static int vmx_setup_l1d_flush(enum vmx_l1d_flush_state l1tf) 


	l1tf_vmx_mitigation = l1tf;



	if (l1tf == VMENTER_L1D_FLUSH_NEVER)

		return 0;



	if (l1tf != VMENTER_L1D_FLUSH_NEVER)

		static_branch_enable(&vmx_l1d_should_flush);

	else

		static_branch_disable(&vmx_l1d_should_flush);



	if (l1tf == VMENTER_L1D_FLUSH_ALWAYS)

		static_branch_enable(&vmx_l1d_flush_always);

	else

		static_branch_disable(&vmx_l1d_flush_always);

	return 0;

}
@@ -249,7 +252,7 @@ static int vmentry_l1d_flush_parse(const char *s) 


	if (s) {

		for (i = 0; i < ARRAY_SIZE(vmentry_l1d_param); i++) {

			if (!strcmp(s, vmentry_l1d_param[i].option))

			if (sysfs_streq(s, vmentry_l1d_param[i].option))

				return vmentry_l1d_param[i].cmd;

		}

	}
@@ -293,7 +296,7 @@ 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, NULL, S_IRUGO);

module_param_cb(vmentry_l1d_flush, &vmentry_l1d_flush_ops, NULL, 0644);



struct kvm_vmx {

	struct kvm kvm;