From 895ae47f9918833c3a880fbccd41e0692b37e7d9 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Fri, 13 Jul 2018 16:23:22 +0200 Subject: [PATCH] x86/kvm: Allow runtime control of L1D flush All mitigation modes can be switched at run time with a static key now: - Use sysfs_streq() instead of strcmp() to handle the trailing new line from sysfs writes correctly. - Make the static key management handle multiple invocations properly. - Set the module parameter file to RW Signed-off-by: Thomas Gleixner Tested-by: Jiri Kosina Reviewed-by: Greg Kroah-Hartman Reviewed-by: Josh Poimboeuf Link: https://lkml.kernel.org/r/20180713142322.954525119@linutronix.de --- arch/x86/kernel/cpu/bugs.c | 2 +- arch/x86/kvm/vmx.c | 13 ++++++++----- 2 files changed, 9 insertions(+), 6 deletions(-) diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 1b3dc58..7df7df9 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -660,7 +660,7 @@ void x86_spec_ctrl_setup_ap(void) #define pr_fmt(fmt) "L1TF: " fmt #if IS_ENABLED(CONFIG_KVM_INTEL) -enum vmx_l1d_flush_state l1tf_vmx_mitigation __ro_after_init = VMENTER_L1D_FLUSH_AUTO; +enum vmx_l1d_flush_state l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_AUTO; EXPORT_SYMBOL_GPL(l1tf_vmx_mitigation); #endif diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 12b1a5d..08fcd59 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -234,12 +234,15 @@ static int vmx_setup_l1d_flush(enum vmx_l1d_flush_state l1tf) l1tf_vmx_mitigation = l1tf; - if (l1tf == VMENTER_L1D_FLUSH_NEVER) - return 0; + if (l1tf != VMENTER_L1D_FLUSH_NEVER) + static_branch_enable(&vmx_l1d_should_flush); + else + static_branch_disable(&vmx_l1d_should_flush); - static_branch_enable(&vmx_l1d_should_flush); if (l1tf == VMENTER_L1D_FLUSH_ALWAYS) static_branch_enable(&vmx_l1d_flush_always); + else + static_branch_disable(&vmx_l1d_flush_always); return 0; } @@ -249,7 +252,7 @@ static int vmentry_l1d_flush_parse(const char *s) if (s) { for (i = 0; i < ARRAY_SIZE(vmentry_l1d_param); i++) { - if (!strcmp(s, vmentry_l1d_param[i].option)) + if (sysfs_streq(s, vmentry_l1d_param[i].option)) return vmentry_l1d_param[i].cmd; } } @@ -293,7 +296,7 @@ static const struct kernel_param_ops vmentry_l1d_flush_ops = { .set = vmentry_l1d_flush_set, .get = vmentry_l1d_flush_get, }; -module_param_cb(vmentry_l1d_flush, &vmentry_l1d_flush_ops, NULL, S_IRUGO); +module_param_cb(vmentry_l1d_flush, &vmentry_l1d_flush_ops, NULL, 0644); struct kvm_vmx { struct kvm kvm; -- 2.7.4