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

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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: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220303154127.202856-9-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
David Woodhouse 2022-03-03 15:41:18 +00:00 committed by Paolo Bonzini
parent 8733068b9b
commit 35025735a7
4 changed files with 45 additions and 0 deletions
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9
arch/x86/kvm/x86.c
View File

@ -6505,6 +6505,15 @@ set_pit2_out:
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);

32
arch/x86/kvm/xen.c
View File

@ -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,

1
arch/x86/kvm/xen.h
View File

@ -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);

3
include/uapi/linux/kvm.h
View File

@ -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)