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Commit 4c6523ec authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

x86/kvm: Add static key for flush always 



Avoid the conditional in the L1D flush control path.

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/20180713142322.790914912@linutronix.de
parent 7db92e16

arch/x86/kvm/vmx.c

+11 −5
Original line number Diff line number Diff line
@@ -192,6 +192,7 @@ module_param(ple_window_max, uint, 0444); 
extern const ulong vmx_return;



static DEFINE_STATIC_KEY_FALSE(vmx_l1d_should_flush);

static DEFINE_STATIC_KEY_FALSE(vmx_l1d_flush_always);



/* Storage for pre module init parameter parsing */

static enum vmx_l1d_flush_state __read_mostly vmentry_l1d_flush_param = VMENTER_L1D_FLUSH_AUTO;
@@ -232,8 +233,12 @@ static int vmx_setup_l1d_flush(enum vmx_l1d_flush_state l1tf) 


	l1tf_vmx_mitigation = l1tf;



	if (l1tf != VMENTER_L1D_FLUSH_NEVER)

	if (l1tf == VMENTER_L1D_FLUSH_NEVER)

		return 0;



	static_branch_enable(&vmx_l1d_should_flush);

	if (l1tf == VMENTER_L1D_FLUSH_ALWAYS)

		static_branch_enable(&vmx_l1d_flush_always);

	return 0;

}
@@ -9651,7 +9656,6 @@ static void *vmx_l1d_flush_pages; 
static void vmx_l1d_flush(struct kvm_vcpu *vcpu)

{

	int size = PAGE_SIZE << L1D_CACHE_ORDER;

	bool always;



	/*

	 * This code is only executed when the the flush mode is 'cond' or
@@ -9661,8 +9665,10 @@ static void vmx_l1d_flush(struct kvm_vcpu *vcpu) 
	 * it. The flush bit gets set again either from vcpu_run() or from

	 * one of the unsafe VMEXIT handlers.

	 */

	always = l1tf_vmx_mitigation == VMENTER_L1D_FLUSH_ALWAYS;

	vcpu->arch.l1tf_flush_l1d = always;

	if (static_branch_unlikely(&vmx_l1d_flush_always))

		vcpu->arch.l1tf_flush_l1d = true;

	else

		vcpu->arch.l1tf_flush_l1d = false;



	vcpu->stat.l1d_flush++;