[PATCH v5 03/18] kvm: x86: Introduce APICv inhibit reason bits

Suravee Suthikulpanit
2019-11-14T20:17:05Z

There are several reasons in which a VM needs to deactivate APICv
e.g. disable APICv via parameter during module loading, or when
enable Hyper-V SynIC support. Additional inhibit reasons will be
introduced later on when dynamic APICv is supported,

Introduce KVM APICv inhibit reason bits along with a new variable,
apicv_inhibit_reasons, to help keep track of APICv state for each VM,

Initially, the APICV_INHIBIT_REASON_DISABLE bit is used to indicate
the case where APICv is disabled during KVM module load.
(e.g. insmod kvm_amd avic=0 or insmod kvm_intel enable_apicv=0).

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
---
arch/x86/include/asm/kvm_host.h | 5 +++++
arch/x86/kvm/svm.c | 13 ++++++++++++-
arch/x86/kvm/vmx/vmx.c | 1 +
arch/x86/kvm/x86.c | 20 +++++++++++++++++++-
4 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 632589a..c60786a 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -847,6 +847,8 @@ enum kvm_irqchip_mode {
KVM_IRQCHIP_SPLIT, /* created with KVM_CAP_SPLIT_IRQCHIP */
};

+#define APICV_INHIBIT_REASON_DISABLE 0
+
struct kvm_arch {
unsigned long n_used_mmu_pages;
unsigned long n_requested_mmu_pages;
@@ -877,6 +879,7 @@ struct kvm_arch {
struct kvm_apic_map *apic_map;

bool apic_access_page_done;
+ unsigned long apicv_inhibit_reasons;

gpa_t wall_clock;

@@ -1441,6 +1444,8 @@ 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 d53ffb8..3395e4c 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1997,6 +1997,17 @@ static int avic_vm_init(struct kvm *kvm)
return err;
}

+static int svm_vm_init(struct kvm *kvm)
+{
+ int ret = 0;
+
+ if (avic)
+ ret = avic_vm_init(kvm);
+
+ kvm_apicv_init(kvm, (avic && !ret));
+ return ret;
+}
+
static inline int
avic_update_iommu_vcpu_affinity(struct kvm_vcpu *vcpu, int cpu, bool r)
{
@@ -7195,7 +7206,7 @@ static bool svm_apic_init_signal_blocked(struct kvm_vcpu *vcpu)

.vm_alloc = svm_vm_alloc,
.vm_free = svm_vm_free,
- .vm_init = avic_vm_init,
+ .vm_init = svm_vm_init,
.vm_destroy = svm_vm_destroy,

.prepare_guest_switch = svm_prepare_guest_switch,
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 2aa14d5..d6d1c862 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6848,6 +6848,7 @@ static int vmx_vm_init(struct kvm *kvm)
break;
}
}
+ 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 4cbb948..4d19566 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -7329,6 +7329,23 @@ 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_inhibit_reasons) == 0);
+}
+EXPORT_SYMBOL_GPL(kvm_apicv_activated);
+
+void kvm_apicv_init(struct kvm *kvm, bool enable)
+{
+ if (enable)
+ clear_bit(APICV_INHIBIT_REASON_DISABLE,
+ &kvm->arch.apicv_inhibit_reasons);
+ else
+ set_bit(APICV_INHIBIT_REASON_DISABLE,
+ &kvm->arch.apicv_inhibit_reasons);
+}
+EXPORT_SYMBOL_GPL(kvm_apicv_init);
+
static void kvm_sched_yield(struct kvm *kvm, unsigned long dest_id)
{
struct kvm_vcpu *target = NULL;
@@ -9347,10 +9364,11 @@ 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;
+ if (kvm_apicv_activated(vcpu->kvm))
+ vcpu->arch.apicv_active = kvm_x86_ops->get_enable_apicv(vcpu->kvm);
} else
static_key_slow_inc(&kvm_no_apic_vcpu);

--
1.8.3.1