[RFC,15/26] KVM: VMX: Sync update of Host HFI table to Guest

Commit Message

Zhao Liu Feb. 3, 2024, 9:12 a.m. UTC

From: Zhuocheng Ding <[e-mail]>

The HFI table could be updated via thermal interrupt as the actual
operating conditions of the processor change during runtime [1], so it
is required to synchronize hardware hint changes to Guest's HFI table in
time.

Provide the interfaces to register/unregister the Host's HFI update,
and in the callback of the notification, make HFI update request to
update Guest's HFI table before entering Guest.

[1]: SDM, vol. 3B, section 15.6.7 Hardware Feedback Interface and Intel
     Thread Director Structure Dynamic Update

Tested-by: Yanting Jiang <[e-mail]>
Signed-off-by: Zhuocheng Ding <[e-mail]>
Co-developed-by: Zhao Liu <[e-mail]>
Signed-off-by: Zhao Liu <[e-mail]>
---
 arch/x86/kvm/vmx/vmx.c | 59 ++++++++++++++++++++++++++++++++++++++++++
 arch/x86/kvm/vmx/vmx.h |  8 ++++++
 2 files changed, 67 insertions(+)

Patch

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 93c47ba0817b..0ad5e3473a28 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -1651,6 +1651,61 @@  static void vmx_update_hfi_table(struct kvm *kvm)
 		vmx_inject_therm_interrupt(kvm_get_vcpu(kvm, 0));
 }
 
+static void vmx_hfi_notifier_register(struct kvm *kvm)
+{
+	struct kvm_vmx *kvm_vmx = to_kvm_vmx(kvm);
+	struct hfi_desc *kvm_vmx_hfi = &kvm_vmx->pkg_therm.hfi_desc;
+
+	if (!intel_hfi_enabled())
+		return;
+
+	if (!vmx_hfi_initialized(kvm_vmx))
+		return;
+
+	if (kvm_vmx_hfi->has_hfi_instance)
+		return;
+
+	/*
+	 * HFI/ITD virtualization is supported on the platforms with only
+	 * 1 HFI instance. Just register notifier for vCPU 0.
+	 */
+	kvm_vmx_hfi->has_hfi_instance =
+		!intel_hfi_notifier_register(&kvm_vmx_hfi->hfi_nb,
+					     kvm_get_vcpu(kvm, 0)->cpu);
+}
+
+static void vmx_hfi_notifier_unregister(struct kvm *kvm)
+{
+	struct kvm_vmx *kvm_vmx = to_kvm_vmx(kvm);
+	struct hfi_desc *kvm_vmx_hfi = &kvm_vmx->pkg_therm.hfi_desc;
+
+	if (!kvm_vmx_hfi->has_hfi_instance)
+		return;
+
+	intel_hfi_notifier_unregister(&kvm_vmx_hfi->hfi_nb,
+				      kvm_get_vcpu(kvm, 0)->cpu);
+	kvm_vmx_hfi->has_hfi_instance = false;
+}
+
+static int vmx_hfi_update_notify(struct notifier_block *nb,
+				 unsigned long code, void *data)
+{
+	struct hfi_desc *kvm_vmx_hfi;
+	struct kvm *kvm;
+
+	kvm_vmx_hfi = container_of(nb, struct hfi_desc, hfi_nb);
+	kvm = &kvm_vmx_hfi->vmx->kvm;
+
+	/*
+	 * Don't need to check if vcpu 0 belongs to
+	 * kvm_vmx_hfi->host_hfi_instance since currently ITD/HFI
+	 * virtualization is only supported for client platforms
+	 * (with only one HFI instance).
+	 */
+	kvm_make_request(KVM_REQ_HFI_UPDATE, kvm_get_vcpu(kvm, 0));
+	return NOTIFY_OK;
+}
+
 static void vmx_dynamic_update_hfi_table(struct kvm_vcpu *vcpu)
 {
 	struct kvm_vmx *kvm_vmx = to_kvm_vmx(vcpu->kvm);
@@ -7871,8 +7926,11 @@  static int vmx_vcpu_create(struct kvm_vcpu *vcpu)
 static int vmx_vm_init_pkg_therm(struct kvm *kvm)
 {
 	struct pkg_therm_desc *pkg_therm = &to_kvm_vmx(kvm)->pkg_therm;
+	struct hfi_desc *kvm_vmx_hfi = &pkg_therm->hfi_desc;
 
 	mutex_init(&pkg_therm->pkg_therm_lock);
+	kvm_vmx_hfi->hfi_nb.notifier_call = vmx_hfi_update_notify;
+	kvm_vmx_hfi->vmx = to_kvm_vmx(kvm);
 	return 0;
 }
 
@@ -8542,6 +8600,7 @@  static void vmx_vm_destroy(struct kvm *kvm)
 	struct kvm_vmx *kvm_vmx = to_kvm_vmx(kvm);
 	struct hfi_desc *kvm_vmx_hfi = &kvm_vmx->pkg_therm.hfi_desc;
 
+	vmx_hfi_notifier_unregister(kvm);
 	kfree(kvm_vmx_hfi->hfi_table.base_addr);
 	free_pages((unsigned long)kvm_vmx->pid_table, vmx_get_pid_table_order(kvm));
 }
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index 63874aad7ae3..ff205bc0e99a 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -395,6 +395,11 @@  struct vcpu_vmx {
  *			the vCPU is running on.
  *			When KVM updates the Guest's HFI table, it writes the local
  *			virtual HFI table to the Guest HFI table memory in @table_base.
+ * @has_hfi_instance:	Flag indicates if VM registers @hfi_nb on Host's HFI instance.
+ * @hfi_nb:		Notifier block to be registered in Host HFI instance.
+ * @vmx:		Points to the kvm_vmx where the current nb is located.
+ *			Used to get the corresponding kvm_vmx of the nb when it
+ *			is executed.
  *
  * A set of status flags and feature information, used to maintain local virtual HFI table
  * and sync updates to Guest HFI table.
@@ -409,6 +414,9 @@  struct hfi_desc {
 	gpa_t			table_base;
 	struct			hfi_features hfi_features;
 	struct hfi_table	hfi_table;
+	bool			has_hfi_instance;
+	struct notifier_block	hfi_nb;
+	struct kvm_vmx		*vmx;
 };
 
 struct pkg_therm_desc {