Commit 35025735 authored by David Woodhouse's avatar David Woodhouse Committed by Paolo Bonzini
Browse files

KVM: x86/xen: Support direct injection of event channel events 



This adds a KVM_XEN_HVM_EVTCHN_SEND ioctl which allows direct injection
of events given an explicit { vcpu, port, priority } in precisely the
same form that those fields are given in the IRQ routing table.

Userspace is currently able to inject 2-level events purely by setting
the bits in the shared_info and vcpu_info, but FIFO event channels are
harder to deal with; we will need the kernel to take sole ownership of
delivery when we support those.

A patch advertising this feature with a new bit in the KVM_CAP_XEN_HVM
ioctl will be added in a subsequent patch.

Signed-off-by: default avatarDavid Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220303154127.202856-9-dwmw2@infradead.org>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 8733068b

arch/x86/kvm/x86.c

+9 −0
Original line number Diff line number Diff line
@@ -6505,6 +6505,15 @@ long kvm_arch_vm_ioctl(struct file *filp, 
		r = kvm_xen_hvm_set_attr(kvm, &xha);

		break;

	}

	case KVM_XEN_HVM_EVTCHN_SEND: {

		struct kvm_irq_routing_xen_evtchn uxe;



		r = -EFAULT;

		if (copy_from_user(&uxe, argp, sizeof(uxe)))

			goto out;

		r = kvm_xen_hvm_evtchn_send(kvm, &uxe);

		break;

	}

#endif

	case KVM_SET_CLOCK:

		r = kvm_vm_ioctl_set_clock(kvm, argp);

arch/x86/kvm/xen.c

+32 −0
Original line number Diff line number Diff line
@@ -1086,6 +1086,38 @@ int kvm_xen_setup_evtchn(struct kvm *kvm, 
	return 0;

}



/*

 * Explicit event sending from userspace with KVM_XEN_HVM_EVTCHN_SEND ioctl.

 */

int kvm_xen_hvm_evtchn_send(struct kvm *kvm, struct kvm_irq_routing_xen_evtchn *uxe)

{

	struct kvm_xen_evtchn e;

	int ret;



	if (!uxe->port || uxe->port >= max_evtchn_port(kvm))

		return -EINVAL;



	/* We only support 2 level event channels for now */

	if (uxe->priority != KVM_IRQ_ROUTING_XEN_EVTCHN_PRIO_2LEVEL)

		return -EINVAL;



	e.port = uxe->port;

	e.vcpu_id = uxe->vcpu;

	e.vcpu_idx = -1;

	e.priority = uxe->priority;



	ret = kvm_xen_set_evtchn(&e, kvm);



	/*

	 * None of that 'return 1 if it actually got delivered' nonsense.

	 * We don't care if it was masked (-ENOTCONN) either.

	 */

	if (ret > 0 || ret == -ENOTCONN)

		ret = 0;



	return ret;

}



void kvm_xen_destroy_vcpu(struct kvm_vcpu *vcpu)

{

	kvm_gfn_to_pfn_cache_destroy(vcpu->kvm,

arch/x86/kvm/xen.h

+1 −0
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ int kvm_xen_vcpu_set_attr(struct kvm_vcpu *vcpu, struct kvm_xen_vcpu_attr *data) 
int kvm_xen_vcpu_get_attr(struct kvm_vcpu *vcpu, struct kvm_xen_vcpu_attr *data);

int kvm_xen_hvm_set_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data);

int kvm_xen_hvm_get_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data);

int kvm_xen_hvm_evtchn_send(struct kvm *kvm, struct kvm_irq_routing_xen_evtchn *evt);

int kvm_xen_write_hypercall_page(struct kvm_vcpu *vcpu, u64 data);

int kvm_xen_hvm_config(struct kvm *kvm, struct kvm_xen_hvm_config *xhc);

void kvm_xen_init_vm(struct kvm *kvm);

include/uapi/linux/kvm.h

+3 −0
Original line number Diff line number Diff line
@@ -1699,6 +1699,9 @@ struct kvm_xen_hvm_attr { 
#define KVM_XEN_VCPU_GET_ATTR	_IOWR(KVMIO, 0xca, struct kvm_xen_vcpu_attr)

#define KVM_XEN_VCPU_SET_ATTR	_IOW(KVMIO,  0xcb, struct kvm_xen_vcpu_attr)



/* Available with KVM_CAP_XEN_HVM / KVM_XEN_HVM_CONFIG_EVTCHN_SEND */

#define KVM_XEN_HVM_EVTCHN_SEND	_IOW(KVMIO,  0xd0, struct kvm_irq_routing_xen_evtchn)



#define KVM_GET_SREGS2             _IOR(KVMIO,  0xcc, struct kvm_sregs2)

#define KVM_SET_SREGS2             _IOW(KVMIO,  0xcd, struct kvm_sregs2)