diff options
Diffstat (limited to 'arch/x86/kvm/svm.c')
| -rw-r--r-- | arch/x86/kvm/svm.c | 106 |
1 files changed, 103 insertions, 3 deletions
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 282aeff5d100..f66fc2ee9058 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -299,6 +299,54 @@ static bool npt_enabled = true; static bool npt_enabled; #endif +/* + * These 2 parameters are used to config the controls for Pause-Loop Exiting: + * pause_filter_count: On processors that support Pause filtering(indicated + * by CPUID Fn8000_000A_EDX), the VMCB provides a 16 bit pause filter + * count value. On VMRUN this value is loaded into an internal counter. + * Each time a pause instruction is executed, this counter is decremented + * until it reaches zero at which time a #VMEXIT is generated if pause + * intercept is enabled. Refer to AMD APM Vol 2 Section 15.14.4 Pause + * Intercept Filtering for more details. + * This also indicate if ple logic enabled. + * + * pause_filter_thresh: In addition, some processor families support advanced + * pause filtering (indicated by CPUID Fn8000_000A_EDX) upper bound on + * the amount of time a guest is allowed to execute in a pause loop. + * In this mode, a 16-bit pause filter threshold field is added in the + * VMCB. The threshold value is a cycle count that is used to reset the + * pause counter. As with simple pause filtering, VMRUN loads the pause + * count value from VMCB into an internal counter. Then, on each pause + * instruction the hardware checks the elapsed number of cycles since + * the most recent pause instruction against the pause filter threshold. + * If the elapsed cycle count is greater than the pause filter threshold, + * then the internal pause count is reloaded from the VMCB and execution + * continues. If the elapsed cycle count is less than the pause filter + * threshold, then the internal pause count is decremented. If the count + * value is less than zero and PAUSE intercept is enabled, a #VMEXIT is + * triggered. If advanced pause filtering is supported and pause filter + * threshold field is set to zero, the filter will operate in the simpler, + * count only mode. + */ + +static unsigned short pause_filter_thresh = KVM_DEFAULT_PLE_GAP; +module_param(pause_filter_thresh, ushort, 0444); + +static unsigned short pause_filter_count = KVM_SVM_DEFAULT_PLE_WINDOW; +module_param(pause_filter_count, ushort, 0444); + +/* Default doubles per-vcpu window every exit. */ +static unsigned short pause_filter_count_grow = KVM_DEFAULT_PLE_WINDOW_GROW; +module_param(pause_filter_count_grow, ushort, 0444); + +/* Default resets per-vcpu window every exit to pause_filter_count. */ +static unsigned short pause_filter_count_shrink = KVM_DEFAULT_PLE_WINDOW_SHRINK; +module_param(pause_filter_count_shrink, ushort, 0444); + +/* Default is to compute the maximum so we can never overflow. */ +static unsigned short pause_filter_count_max = KVM_SVM_DEFAULT_PLE_WINDOW_MAX; +module_param(pause_filter_count_max, ushort, 0444); + /* allow nested paging (virtualized MMU) for all guests */ static int npt = true; module_param(npt, int, S_IRUGO); @@ -1198,6 +1246,42 @@ err: return rc; } +static void grow_ple_window(struct kvm_vcpu *vcpu) +{ + struct vcpu_svm *svm = to_svm(vcpu); + struct vmcb_control_area *control = &svm->vmcb->control; + int old = control->pause_filter_count; + + control->pause_filter_count = __grow_ple_window(old, + pause_filter_count, + pause_filter_count_grow, + pause_filter_count_max); + + if (control->pause_filter_count != old) + mark_dirty(svm->vmcb, VMCB_INTERCEPTS); + + trace_kvm_ple_window_grow(vcpu->vcpu_id, + control->pause_filter_count, old); +} + +static void shrink_ple_window(struct kvm_vcpu *vcpu) +{ + struct vcpu_svm *svm = to_svm(vcpu); + struct vmcb_control_area *control = &svm->vmcb->control; + int old = control->pause_filter_count; + + control->pause_filter_count = + __shrink_ple_window(old, + pause_filter_count, + pause_filter_count_shrink, + pause_filter_count); + if (control->pause_filter_count != old) + mark_dirty(svm->vmcb, VMCB_INTERCEPTS); + + trace_kvm_ple_window_shrink(vcpu->vcpu_id, + control->pause_filter_count, old); +} + static __init int svm_hardware_setup(void) { int cpu; @@ -1228,6 +1312,14 @@ static __init int svm_hardware_setup(void) kvm_tsc_scaling_ratio_frac_bits = 32; } + /* Check for pause filtering support */ + if (!boot_cpu_has(X86_FEATURE_PAUSEFILTER)) { + pause_filter_count = 0; + pause_filter_thresh = 0; + } else if (!boot_cpu_has(X86_FEATURE_PFTHRESHOLD)) { + pause_filter_thresh = 0; + } + if (nested) { printk(KERN_INFO "kvm: Nested Virtualization enabled\n"); kvm_enable_efer_bits(EFER_SVME | EFER_LMSLE); @@ -1485,10 +1577,13 @@ static void init_vmcb(struct vcpu_svm *svm) svm->nested.vmcb = 0; svm->vcpu.arch.hflags = 0; - if (boot_cpu_has(X86_FEATURE_PAUSEFILTER) && - !kvm_pause_in_guest(svm->vcpu.kvm)) { - control->pause_filter_count = 3000; + if (pause_filter_count) { + control->pause_filter_count = pause_filter_count; + if (pause_filter_thresh) + control->pause_filter_thresh = pause_filter_thresh; set_intercept(svm, INTERCEPT_PAUSE); + } else { + clr_intercept(svm, INTERCEPT_PAUSE); } if (kvm_vcpu_apicv_active(&svm->vcpu)) @@ -4288,6 +4383,9 @@ static int pause_interception(struct vcpu_svm *svm) struct kvm_vcpu *vcpu = &svm->vcpu; bool in_kernel = (svm_get_cpl(vcpu) == 0); + if (pause_filter_thresh) + grow_ple_window(vcpu); + kvm_vcpu_on_spin(vcpu, in_kernel); return 1; } @@ -5984,6 +6082,8 @@ static void svm_handle_external_intr(struct kvm_vcpu *vcpu) static void svm_sched_in(struct kvm_vcpu *vcpu, int cpu) { + if (pause_filter_thresh) + shrink_ple_window(vcpu); } static inline void avic_post_state_restore(struct kvm_vcpu *vcpu) |