linux-kernel - [PATCH v3 4/7] KVM: x86: nSVM: support PAUSE filter threshold and count when cpu

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Date:   Tue,  1 Mar 2022 16:36:47 +0200
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     kvm@...r.kernel.org
Cc:     Ingo Molnar <mingo@...hat.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jim Mattson <jmattson@...gle.com>, x86@...nel.org,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Joerg Roedel <joro@...tes.org>, linux-kernel@...r.kernel.org,
        Paolo Bonzini <pbonzini@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Maxim Levitsky <mlevitsk@...hat.com>
Subject: [PATCH v3 4/7] KVM: x86: nSVM: support PAUSE filter threshold and count when cpu_pm=on

Allow L1 to use these settings if L0 disables PAUSE interception
(AKA cpu_pm=on)

Signed-off-by: Maxim Levitsky <mlevitsk@...hat.com>
---
 arch/x86/kvm/svm/nested.c |  6 ++++++
 arch/x86/kvm/svm/svm.c    | 17 +++++++++++++++++
 arch/x86/kvm/svm/svm.h    |  2 ++
 3 files changed, 25 insertions(+)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index 37510cb206190..4cb0bc49986d5 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -664,6 +664,12 @@ static void nested_vmcb02_prepare_control(struct vcpu_svm *svm)
 	if (!nested_vmcb_needs_vls_intercept(svm))
 		svm->vmcb->control.virt_ext |= VIRTUAL_VMLOAD_VMSAVE_ENABLE_MASK;
 
+	if (svm->pause_filter_enabled)
+		svm->vmcb->control.pause_filter_count = svm->nested.ctl.pause_filter_count;
+
+	if (svm->pause_threshold_enabled)
+		svm->vmcb->control.pause_filter_thresh = svm->nested.ctl.pause_filter_thresh;
+
 	nested_svm_transition_tlb_flush(vcpu);
 
 	/* Enter Guest-Mode */
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 6a571eed32ef4..52198e63c5fc4 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4008,6 +4008,17 @@ 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);
 
+	if (kvm_pause_in_guest(vcpu->kvm)) {
+		svm->pause_filter_enabled = pause_filter_count > 0 &&
+					    guest_cpuid_has(vcpu, X86_FEATURE_PAUSEFILTER);
+
+		svm->pause_threshold_enabled = pause_filter_thresh > 0 &&
+					    guest_cpuid_has(vcpu, X86_FEATURE_PFTHRESHOLD);
+	} else {
+		svm->pause_filter_enabled = false;
+		svm->pause_threshold_enabled = false;
+	}
+
 	svm_recalc_instruction_intercepts(vcpu, svm);
 
 	/* For sev guests, the memory encryption bit is not reserved in CR3.  */
@@ -4763,6 +4774,12 @@ static __init void svm_set_cpu_caps(void)
 		if (vls)
 			kvm_cpu_cap_set(X86_FEATURE_V_VMSAVE_VMLOAD);
 
+		if (pause_filter_count)
+			kvm_cpu_cap_set(X86_FEATURE_PAUSEFILTER);
+
+		if (pause_filter_thresh)
+			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 a3c93f9c02847..6fa81eb3ffb78 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -234,6 +234,8 @@ struct vcpu_svm {
 	bool tsc_scaling_enabled          : 1;
 	bool lbrv_enabled                 : 1;
 	bool v_vmload_vmsave_enabled      : 1;
+	bool pause_filter_enabled         : 1;
+	bool pause_threshold_enabled      : 1;
 
 	u32 ldr_reg;
 	u32 dfr_reg;
-- 
2.26.3