| From foo@baz Tue Aug 14 16:14:56 CEST 2018 |
| From: Thomas Gleixner <tglx@linutronix.de> |
| Date: Fri, 13 Jul 2018 16:23:20 +0200 |
| Subject: x86/kvm: Add static key for flush always |
| |
| From: Thomas Gleixner <tglx@linutronix.de> |
| |
| 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: David Woodhouse <dwmw@amazon.co.uk> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| arch/x86/kvm/vmx.c | 16 +++++++++++----- |
| 1 file changed, 11 insertions(+), 5 deletions(-) |
| |
| --- a/arch/x86/kvm/vmx.c |
| +++ b/arch/x86/kvm/vmx.c |
| @@ -193,6 +193,7 @@ module_param(ple_window_max, int, S_IRUG |
| 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; |
| @@ -233,8 +234,12 @@ static int vmx_setup_l1d_flush(enum vmx_ |
| |
| 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; |
| } |
| |
| @@ -8625,7 +8630,6 @@ 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 |
| @@ -8635,8 +8639,10 @@ static void vmx_l1d_flush(struct kvm_vcp |
| * 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++; |
| |