[v4,03/17] kvm: x86: Introduce APICv deactivate bits

Commit Message

Suthikulpanit, Suravee Nov. 1, 2019, 10:41 p.m. UTC

Currently, after a VM boots with APICv enabled, it could be deactivated
due to various reasons (e.g. Hyper-v synic).

Introduce KVM APICv deactivate bits along with a new variable
struct kvm_arch.apicv_deact_msk to help keep track of why APICv is
deactivated for each VM.

Signed-off-by: Suravee Suthikulpanit <[e-mail]>
---
 arch/x86/include/asm/kvm_host.h |  5 +++++
 arch/x86/kvm/svm.c              |  3 +++
 arch/x86/kvm/vmx/vmx.c          |  4 ++++
 arch/x86/kvm/x86.c              | 22 +++++++++++++++++++++-
 4 files changed, 33 insertions(+), 1 deletion(-)

Comments

Paolo Bonzini Nov. 2, 2019, 9:51 a.m. UTC | #1

On 01/11/19 23:41, Suthikulpanit, Suravee wrote:
> +	unsigned long apicv_deact_msk;

No abbrev fld names. :)  I can change this to something like
apicv_inhibit_reasons if there are no other issues (and likewise
s/APICV_DEACT_BIT_/APICV_INHIBIT_REASON_/).

> 
> +bool kvm_apicv_activated(struct kvm *kvm)
> +{
> +	return (READ_ONCE(kvm->arch.apicv_deact_msk) == 0);
> +}

Using READ_ONCE introduces a risk of races.  I'll check during a more
thorough review if it's worth introducing separate kvm_apicv_active and
kvm_apicv_active_nolock functions.

Paolo

Patch

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 843799b..1c05363 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -852,6 +852,8 @@  enum kvm_irqchip_mode {
 	KVM_IRQCHIP_SPLIT,        /* created with KVM_CAP_SPLIT_IRQCHIP */
 };
 
+#define APICV_DEACT_BIT_DISABLE    0
+
 struct kvm_arch {
 	unsigned long n_used_mmu_pages;
 	unsigned long n_requested_mmu_pages;
@@ -881,6 +883,7 @@  struct kvm_arch {
 	struct kvm_apic_map *apic_map;
 
 	bool apic_access_page_done;
+	unsigned long apicv_deact_msk;
 
 	gpa_t wall_clock;
 
@@ -1416,6 +1419,8 @@  gpa_t kvm_mmu_gva_to_gpa_system(struct kvm_vcpu *vcpu, gva_t gva,
 				struct x86_exception *exception);
 
 void kvm_vcpu_deactivate_apicv(struct kvm_vcpu *vcpu);
+bool kvm_apicv_activated(struct kvm *kvm);
+void kvm_apicv_init(struct kvm *kvm, bool enable);
 
 int kvm_emulate_hypercall(struct kvm_vcpu *vcpu);
 
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 7090306..a0caf66 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1985,6 +1985,9 @@  static int avic_vm_init(struct kvm *kvm)
 	hash_add(svm_vm_data_hash, &kvm_svm->hnode, kvm_svm->avic_vm_id);
 	spin_unlock_irqrestore(&svm_vm_data_hash_lock, flags);
 
+	/* Enable KVM APICv support */
+	kvm_apicv_init(kvm, true);
+
 	return 0;
 
 free_avic:
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index e4faa00..28b97fb 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6775,6 +6775,10 @@  static int vmx_vm_init(struct kvm *kvm)
 			break;
 		}
 	}
+
+	/* Enable KVM APICv support */
+	kvm_apicv_init(kvm, vmx_get_enable_apicv(kvm));
+
 	return 0;
 }
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 2341f48..70a70a1 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -7201,6 +7201,21 @@  void kvm_vcpu_deactivate_apicv(struct kvm_vcpu *vcpu)
 	kvm_x86_ops->refresh_apicv_exec_ctrl(vcpu);
 }
 
+bool kvm_apicv_activated(struct kvm *kvm)
+{
+	return (READ_ONCE(kvm->arch.apicv_deact_msk) == 0);
+}
+EXPORT_SYMBOL_GPL(kvm_apicv_activated);
+
+void kvm_apicv_init(struct kvm *kvm, bool enable)
+{
+	if (enable)
+		clear_bit(APICV_DEACT_BIT_DISABLE, &kvm->arch.apicv_deact_msk);
+	else
+		set_bit(APICV_DEACT_BIT_DISABLE, &kvm->arch.apicv_deact_msk);
+}
+EXPORT_SYMBOL_GPL(kvm_apicv_init);
+
 static void kvm_sched_yield(struct kvm *kvm, unsigned long dest_id)
 {
 	struct kvm_vcpu *target = NULL;
@@ -9217,13 +9232,15 @@  int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
 		goto fail_free_pio_data;
 
 	if (irqchip_in_kernel(vcpu->kvm)) {
-		vcpu->arch.apicv_active = kvm_x86_ops->get_enable_apicv(vcpu->kvm);
 		r = kvm_create_lapic(vcpu, lapic_timer_advance_ns);
 		if (r < 0)
 			goto fail_mmu_destroy;
 	} else
 		static_key_slow_inc(&kvm_no_apic_vcpu);
 
+	if (irqchip_in_kernel(vcpu->kvm) && kvm_apicv_activated(vcpu->kvm))
+		vcpu->arch.apicv_active = kvm_x86_ops->get_enable_apicv(vcpu->kvm);
+
 	vcpu->arch.mce_banks = kzalloc(KVM_MAX_MCE_BANKS * sizeof(u64) * 4,
 				       GFP_KERNEL_ACCOUNT);
 	if (!vcpu->arch.mce_banks) {
@@ -9322,6 +9339,9 @@  int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 	kvm_page_track_init(kvm);
 	kvm_mmu_init_vm(kvm);
 
+	/* Default to APICv disable */
+	kvm_apicv_init(kvm, false);
+
 	if (kvm_x86_ops->vm_init)
 		return kvm_x86_ops->vm_init(kvm);