x86/kvm: Add static key for flush always
commit 4c6523ec59fe895ea352a650218a6be0653910b1 upstream.
Avoid the conditional in the L1D flush control path.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20180713142322.790914912@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 7590b86..4eb95cb 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -192,6 +192,7 @@
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 @@
l1tf_vmx_mitigation = l1tf;
- if (l1tf != VMENTER_L1D_FLUSH_NEVER)
- static_branch_enable(&vmx_l1d_should_flush);
+ 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;
}
@@ -9687,7 +9692,6 @@
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
@@ -9697,8 +9701,10 @@
* 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++;
