KVM: x86: Rework request for immediate exit
The VMX implementation of enable_irq_window raised
KVM_REQ_IMMEDIATE_EXIT after we checked it in vcpu_enter_guest. This
caused infinite loops on vmentry. Fix it by letting enable_irq_window
signal the need for an immediate exit via its return value and drop
KVM_REQ_IMMEDIATE_EXIT.
This issue only affects nested VMX scenarios.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 18635ae..111b4a0 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -694,7 +694,7 @@
bool (*get_nmi_mask)(struct kvm_vcpu *vcpu);
void (*set_nmi_mask)(struct kvm_vcpu *vcpu, bool masked);
void (*enable_nmi_window)(struct kvm_vcpu *vcpu);
- void (*enable_irq_window)(struct kvm_vcpu *vcpu);
+ int (*enable_irq_window)(struct kvm_vcpu *vcpu);
void (*update_cr8_intercept)(struct kvm_vcpu *vcpu, int tpr, int irr);
int (*vm_has_apicv)(struct kvm *kvm);
void (*hwapic_irr_update)(struct kvm_vcpu *vcpu, int max_irr);
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 15c9ccc..7f896cb 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -3632,7 +3632,7 @@
return ret;
}
-static void enable_irq_window(struct kvm_vcpu *vcpu)
+static int enable_irq_window(struct kvm_vcpu *vcpu)
{
struct vcpu_svm *svm = to_svm(vcpu);
@@ -3646,6 +3646,7 @@
svm_set_vintr(svm);
svm_inject_irq(svm, 0x0);
}
+ return 0;
}
static void enable_nmi_window(struct kvm_vcpu *vcpu)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 0f0cb31..74c525e 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -4398,22 +4398,23 @@
PIN_BASED_NMI_EXITING;
}
-static void enable_irq_window(struct kvm_vcpu *vcpu)
+static int enable_irq_window(struct kvm_vcpu *vcpu)
{
u32 cpu_based_vm_exec_control;
- if (is_guest_mode(vcpu) && nested_exit_on_intr(vcpu)) {
+
+ if (is_guest_mode(vcpu) && nested_exit_on_intr(vcpu))
/*
* We get here if vmx_interrupt_allowed() said we can't
- * inject to L1 now because L2 must run. Ask L2 to exit
- * right after entry, so we can inject to L1 more promptly.
+ * inject to L1 now because L2 must run. The caller will have
+ * to make L2 exit right after entry, so we can inject to L1
+ * more promptly.
*/
- kvm_make_request(KVM_REQ_IMMEDIATE_EXIT, vcpu);
- return;
- }
+ return -EBUSY;
cpu_based_vm_exec_control = vmcs_read32(CPU_BASED_VM_EXEC_CONTROL);
cpu_based_vm_exec_control |= CPU_BASED_VIRTUAL_INTR_PENDING;
vmcs_write32(CPU_BASED_VM_EXEC_CONTROL, cpu_based_vm_exec_control);
+ return 0;
}
static void enable_nmi_window(struct kvm_vcpu *vcpu)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 2a434bf..c522260 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5692,7 +5692,7 @@
int r;
bool req_int_win = !irqchip_in_kernel(vcpu->kvm) &&
vcpu->run->request_interrupt_window;
- bool req_immediate_exit = 0;
+ bool req_immediate_exit = false;
if (vcpu->requests) {
if (kvm_check_request(KVM_REQ_MMU_RELOAD, vcpu))
@@ -5734,8 +5734,6 @@
record_steal_time(vcpu);
if (kvm_check_request(KVM_REQ_NMI, vcpu))
process_nmi(vcpu);
- req_immediate_exit =
- kvm_check_request(KVM_REQ_IMMEDIATE_EXIT, vcpu);
if (kvm_check_request(KVM_REQ_PMU, vcpu))
kvm_handle_pmu_event(vcpu);
if (kvm_check_request(KVM_REQ_PMI, vcpu))
@@ -5757,7 +5755,8 @@
if (vcpu->arch.nmi_pending)
kvm_x86_ops->enable_nmi_window(vcpu);
else if (kvm_cpu_has_injectable_intr(vcpu) || req_int_win)
- kvm_x86_ops->enable_irq_window(vcpu);
+ req_immediate_exit =
+ kvm_x86_ops->enable_irq_window(vcpu) != 0;
if (kvm_lapic_enabled(vcpu)) {
/*
