[PATCH v4 3/6] KVM: x86: nSVM: support PAUSE filtering when L0 doesn't intercept PAUSE

[Maxim Levitsky]

Allow L1 to use PAUSE filtering if L0 doesn't use it.

Signed-off-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
---
 arch/x86/kvm/svm/nested.c | 26 ++++++++++++++++++++++++++
 arch/x86/kvm/svm/svm.c    | 22 +++++++++++++++++++---
 arch/x86/kvm/svm/svm.h    |  2 ++
 3 files changed, 47 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index c1baa3a68ce6..0a0b4b26c91e 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -667,6 +667,29 @@ static void nested_vmcb02_prepare_control(struct vcpu_svm *svm)
 	if (!nested_vmcb_needs_vls_intercept(svm))
 		vmcb02->control.virt_ext |= VIRTUAL_VMLOAD_VMSAVE_ENABLE_MASK;
 
+	if (kvm_pause_in_guest(svm->vcpu.kvm)) {
+		/* use guest values since host doesn't use them */
+		vmcb02->control.pause_filter_count =
+				svm->pause_filter_enabled ?
+				svm->nested.ctl.pause_filter_count : 0;
+
+		vmcb02->control.pause_filter_thresh =
+				svm->pause_threshold_enabled ?
+				svm->nested.ctl.pause_filter_thresh : 0;
+
+	} else if (!vmcb12_is_intercept(&svm->nested.ctl, INTERCEPT_PAUSE)) {
+		/* use host values when guest doesn't use them */
+		vmcb02->control.pause_filter_count = vmcb01->control.pause_filter_count;
+		vmcb02->control.pause_filter_thresh = vmcb01->control.pause_filter_thresh;
+	} else {
+		/*
+		 * Intercept every PAUSE otherwise and
+		 * ignore both host and guest values
+		 */
+		vmcb02->control.pause_filter_count = 0;
+		vmcb02->control.pause_filter_thresh = 0;
+	}
+
 	nested_svm_transition_tlb_flush(vcpu);
 
 	/* Enter Guest-Mode */
@@ -927,6 +950,9 @@ int nested_svm_vmexit(struct vcpu_svm *svm)
 	vmcb12->control.event_inj         = svm->nested.ctl.event_inj;
 	vmcb12->control.event_inj_err     = svm->nested.ctl.event_inj_err;
 
+	if (!kvm_pause_in_guest(vcpu->kvm) && vmcb02->control.pause_filter_count)
+		vmcb01->control.pause_filter_count = vmcb02->control.pause_filter_count;
+
 	nested_svm_copy_common_state(svm->nested.vmcb02.ptr, svm->vmcb01.ptr);
 
 	svm_switch_vmcb(svm, &svm->vmcb01);
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index ec9a1dabdcc3..4c23cb1895ab 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -910,6 +910,9 @@ static void grow_ple_window(struct kvm_vcpu *vcpu)
 	struct vmcb_control_area *control = &svm->vmcb->control;
 	int old = control->pause_filter_count;
 
+	if (kvm_pause_in_guest(vcpu->kvm) || !old)
+		return;
+
 	control->pause_filter_count = __grow_ple_window(old,
 							pause_filter_count,
 							pause_filter_count_grow,
@@ -928,6 +931,9 @@ static void shrink_ple_window(struct kvm_vcpu *vcpu)
 	struct vmcb_control_area *control = &svm->vmcb->control;
 	int old = control->pause_filter_count;
 
+	if (kvm_pause_in_guest(vcpu->kvm) || !old)
+		return;
+
 	control->pause_filter_count =
 				__shrink_ple_window(old,
 						    pause_filter_count,
@@ -2984,7 +2990,6 @@ static int interrupt_window_interception(struct kvm_vcpu *vcpu)
 static int pause_interception(struct kvm_vcpu *vcpu)
 {
 	bool in_kernel;
-
 	/*
 	 * CPL is not made available for an SEV-ES guest, therefore
 	 * vcpu->arch.preempted_in_kernel can never be true.  Just
@@ -2992,8 +2997,7 @@ static int pause_interception(struct kvm_vcpu *vcpu)
 	 */
 	in_kernel = !sev_es_guest(vcpu->kvm) && svm_get_cpl(vcpu) == 0;
 
-	if (!kvm_pause_in_guest(vcpu->kvm))
-		grow_ple_window(vcpu);
+	grow_ple_window(vcpu);
 
 	kvm_vcpu_on_spin(vcpu, in_kernel);
 	return kvm_skip_emulated_instruction(vcpu);
@@ -4020,6 +4024,12 @@ static void svm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
 
 	svm->v_vmload_vmsave_enabled = vls && guest_cpuid_has(vcpu, X86_FEATURE_V_VMSAVE_VMLOAD);
 
+	svm->pause_filter_enabled = kvm_cpu_cap_has(X86_FEATURE_PAUSEFILTER) &&
+			guest_cpuid_has(vcpu, X86_FEATURE_PAUSEFILTER);
+
+	svm->pause_threshold_enabled = kvm_cpu_cap_has(X86_FEATURE_PFTHRESHOLD) &&
+			guest_cpuid_has(vcpu, X86_FEATURE_PFTHRESHOLD);
+
 	svm_recalc_instruction_intercepts(vcpu, svm);
 
 	/* For sev guests, the memory encryption bit is not reserved in CR3.  */
@@ -4773,6 +4783,12 @@ static __init void svm_set_cpu_caps(void)
 		if (lbrv)
 			kvm_cpu_cap_set(X86_FEATURE_LBRV);
 
+		if (boot_cpu_has(X86_FEATURE_PAUSEFILTER))
+			kvm_cpu_cap_set(X86_FEATURE_PAUSEFILTER);
+
+		if (boot_cpu_has(X86_FEATURE_PFTHRESHOLD))
+			kvm_cpu_cap_set(X86_FEATURE_PFTHRESHOLD);
+
 		/* Nested VM can receive #VMEXIT instead of triggering #GP */
 		kvm_cpu_cap_set(X86_FEATURE_SVME_ADDR_CHK);
 	}
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index aaf46b1fbf76..9895fd6a7310 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -237,6 +237,8 @@ struct vcpu_svm {
 	bool tsc_scaling_enabled          : 1;
 	bool v_vmload_vmsave_enabled      : 1;
 	bool lbrv_enabled                 : 1;
+	bool pause_filter_enabled         : 1;
+	bool pause_threshold_enabled      : 1;
 
 	u32 ldr_reg;
 	u32 dfr_reg;
-- 
2.26.3