x86/KVM/VMX: Move the l1tf_flush_l1d test to vmx_l1d_flush() (5b6ccc6c) · Commits · 戴 / test

Currently, vmx_vcpu_run() checks if l1tf_flush_l1d is set and invokes vmx_l1d_flush() if so. This test is unncessary for the "always flush L1D" mode. Move the check to vmx_l1d_flush()'s conditional mode code path. Notes: - vmx_l1d_flush() is likely to get inlined anyway and thus, there's no extra function call. - This inverts the (static) branch prediction, but there hadn't been any explicit likely()/unlikely() annotations before and so it stays as is. Signed-off-by:

Nicolai Stange <nstange@suse.de> Signed-off-by:

Thomas Gleixner <tglx@linutronix.de>

arch/x86/kvm/vmx.c

+6 −4

Original line number	Diff line number	Diff line
		@@ -9693,12 +9693,16 @@ static void vmx_l1d_flush(struct kvm_vcpu *vcpu)
		* 'always'
		*/
		if (static_branch_likely(&vmx_l1d_flush_cond)) {
		bool flush_l1d = vcpu->arch.l1tf_flush_l1d;

		/*
		* Clear the flush bit, it gets set again either from
		* vcpu_run() or from one of the unsafe VMEXIT
		* handlers.
		*/
		vcpu->arch.l1tf_flush_l1d = false;
		if (!flush_l1d)
		return;
		}

		vcpu->stat.l1d_flush++;
		@@ -10228,10 +10232,8 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
		evmcs_rsp = static_branch_unlikely(&enable_evmcs) ?
		(unsigned long)&current_evmcs->host_rsp : 0;

		if (static_branch_unlikely(&vmx_l1d_should_flush)) {
		if (vcpu->arch.l1tf_flush_l1d)
		if (static_branch_unlikely(&vmx_l1d_should_flush))
		vmx_l1d_flush(vcpu);
		}

		asm(
		/* Store host registers */

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