KVM: x86/xen: handle PV timers oneshot mode

If the guest has offloaded the timer virq, handle the following
hypercalls for programming the timer:

    VCPUOP_set_singleshot_timer
    VCPUOP_stop_singleshot_timer
    set_timer_op(timestamp_ns)

The event channel corresponding to the timer virq is then used to inject
events once timer deadlines are met. For now we back the PV timer with
hrtimer.

[ dwmw2: Add save/restore, 32-bit compat mode, immediate delivery,
         don't check timer in kvm_vcpu_has_event() ]

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220303154127.202856-13-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 28 insertions, 0 deletions

diff --git a/arch/x86/kvm/xen.h b/arch/x86/kvm/xen.h
index 54d587aae85b..ee5c4ae0755c 100644
--- a/arch/x86/kvm/xen.h
+++ b/arch/x86/kvm/xen.h
@@ -62,6 +62,20 @@ static inline bool kvm_xen_has_pending_events(struct kvm_vcpu *vcpu)
 		vcpu->arch.xen.evtchn_pending_sel;
 }
 
+static inline bool kvm_xen_timer_enabled(struct kvm_vcpu *vcpu)
+{
+	return !!vcpu->arch.xen.timer_virq;
+}
+
+static inline int kvm_xen_has_pending_timer(struct kvm_vcpu *vcpu)
+{
+	if (kvm_xen_hypercall_enabled(vcpu->kvm) && kvm_xen_timer_enabled(vcpu))
+		return atomic_read(&vcpu->arch.xen.timer_pending);
+
+	return 0;
+}
+
+void kvm_xen_inject_timer_irqs(struct kvm_vcpu *vcpu);
 #else
 static inline int kvm_xen_write_hypercall_page(struct kvm_vcpu *vcpu, u64 data)
 {
@@ -107,6 +121,20 @@ static inline bool kvm_xen_has_pending_events(struct kvm_vcpu *vcpu)
 {
 	return false;
 }
+
+static inline int kvm_xen_has_pending_timer(struct kvm_vcpu *vcpu)
+{
+	return 0;
+}
+
+static inline void kvm_xen_inject_timer_irqs(struct kvm_vcpu *vcpu)
+{
+}
+
+static inline bool kvm_xen_timer_enabled(struct kvm_vcpu *vcpu)
+{
+	return false;
+}
 #endif
 
 int kvm_xen_hypercall(struct kvm_vcpu *vcpu);