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x86/KVM/VMX: Move the l1tf_flush_l1d test to vmx_l1d_flush()

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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>
This commit is contained in:
Nicolai Stange 2018-07-21 22:35:28 +02:00 committed by Thomas Gleixner
parent 427362a142
commit 5b6ccc6c3b
1 changed files with 6 additions and 4 deletions
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10
arch/x86/kvm/vmx.c
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@ -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)
vmx_l1d_flush(vcpu);
}
if (static_branch_unlikely(&vmx_l1d_should_flush))
vmx_l1d_flush(vcpu);
asm(
/* Store host registers */