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x86/kvm: Add static key for flush always

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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
This commit is contained in:
Thomas Gleixner 2018-07-13 16:23:20 +02:00
parent 7db92e165a
commit 4c6523ec59
1 changed files with 11 additions and 5 deletions
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16
arch/x86/kvm/vmx.c
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@ -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)
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;
}
@ -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++;