[PATCH v2 5/6] KVM: x86: nSVM: support PAUSE filter threshold and count when cpu_pm=on

From: Maxim Levitsky
Date: Mon Nov 01 2021 - 10:04:53 EST


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

Signed-off-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
---
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 2dc97cca68f7c..15be37368380d 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -617,6 +617,12 @@ 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 77fd0922c4060..ff1447a3551fc 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -1026,6 +1026,12 @@ 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);
}
@@ -4163,6 +4169,17 @@ 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. */
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index ec8dd09e41e69..75781d66cbd60 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -166,6 +166,8 @@ 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