From: Joao Martins <joao.m.martins@xxxxxxxxxx>
Userspace registers a sending @port to either deliver to an @eventfd
or directly back to a local event channel port.
After binding events the guest or host may wish to bind those
events to a particular vcpu. This is usually done for unbound
and and interdomain events. Update requests are handled via the
KVM_XEN_EVTCHN_UPDATE flag.
Unregistered ports are handled by the emulator.
Co-developed-by: Ankur Arora <ankur.a.arora@xxxxxxxxxx>
Co-developed-By: David Woodhouse <dwmw@xxxxxxxxxxxx>
Signed-off-by: Joao Martins <joao.m.martins@xxxxxxxxxx>
Signed-off-by: Ankur Arora <ankur.a.arora@xxxxxxxxxx>
Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx>
---
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/xen.c | 274 ++++++++++++++++++++++++++++++--
include/uapi/linux/kvm.h | 27 ++++
3 files changed, 287 insertions(+), 15 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 0361e6f3dac0..2068ee84f196 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1019,6 +1019,7 @@ struct kvm_xen {
bool long_mode;
u8 upcall_vector;
struct gfn_to_pfn_cache shinfo_cache;
+ struct idr evtchn_ports;
};
enum kvm_irqchip_mode {
diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c
index 15ae237131d5..0cc9f6a4f10f 100644
--- a/arch/x86/kvm/xen.c
+++ b/arch/x86/kvm/xen.c
@@ -11,6 +11,7 @@
#include "lapic.h"
#include "hyperv.h"
+#include <linux/eventfd.h>
#include <linux/kvm_host.h>
#include <linux/sched/stat.h>
@@ -21,6 +22,9 @@
#include "trace.h"
+static int kvm_xen_setattr_evtchn(struct kvm *kvm, struct kvm_xen_hvm_attr *data);
+static bool kvm_xen_hcall_evtchn_send(struct kvm_vcpu *vcpu, u64 param, u64 *r);
+
DEFINE_STATIC_KEY_DEFERRED_FALSE(kvm_xen_enabled, HZ);
static int kvm_xen_shared_info_init(struct kvm *kvm, gfn_t gfn)
@@ -368,36 +372,44 @@ int kvm_xen_hvm_set_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data)
{
int r = -ENOENT;
- mutex_lock(&kvm->lock);
switch (data->type) {
case KVM_XEN_ATTR_TYPE_LONG_MODE:
if (!IS_ENABLED(CONFIG_64BIT) && data->u.long_mode) {
r = -EINVAL;
} else {
+ mutex_lock(&kvm->lock);
kvm->arch.xen.long_mode = !!data->u.long_mode;
+ mutex_unlock(&kvm->lock);
r = 0;
}
break;
case KVM_XEN_ATTR_TYPE_SHARED_INFO:
+ mutex_lock(&kvm->lock);
r = kvm_xen_shared_info_init(kvm, data->u.shared_info.gfn);
+ mutex_unlock(&kvm->lock);
break;
case KVM_XEN_ATTR_TYPE_UPCALL_VECTOR:
if (data->u.vector && data->u.vector < 0x10)
r = -EINVAL;
else {
+ mutex_lock(&kvm->lock);
kvm->arch.xen.upcall_vector = data->u.vector;
+ mutex_unlock(&kvm->lock);
r = 0;
}
break;
+ case KVM_XEN_ATTR_TYPE_EVTCHN:
+ r = kvm_xen_setattr_evtchn(kvm, data);
+ break;
+
default:
break;
}
- mutex_unlock(&kvm->lock);
return r;
}
@@ -775,18 +787,6 @@ int kvm_xen_hvm_config(struct kvm *kvm, struct kvm_xen_hvm_config *xhc)
return 0;
}
-void kvm_xen_init_vm(struct kvm *kvm)
-{
-}
-
-void kvm_xen_destroy_vm(struct kvm *kvm)
-{
- kvm_gfn_to_pfn_cache_destroy(kvm, &kvm->arch.xen.shinfo_cache);
-
- if (kvm->arch.xen_hvm_config.msr)
- static_branch_slow_dec_deferred(&kvm_xen_enabled);
-}
-
static int kvm_xen_hypercall_set_result(struct kvm_vcpu *vcpu, u64 result)
{
kvm_rax_write(vcpu, result);
@@ -806,7 +806,8 @@ static int kvm_xen_hypercall_complete_userspace(struct kvm_vcpu *vcpu)
int kvm_xen_hypercall(struct kvm_vcpu *vcpu)
{
bool longmode;
- u64 input, params[6];
+ u64 input, params[6], r = -ENOSYS;
+ bool handled = false;
input = (u64)kvm_register_read(vcpu, VCPU_REGS_RAX);
@@ -837,6 +838,19 @@ int kvm_xen_hypercall(struct kvm_vcpu *vcpu)
trace_kvm_xen_hypercall(input, params[0], params[1], params[2],
params[3], params[4], params[5]);
+ switch (input) {
+ case __HYPERVISOR_event_channel_op:
+ if (params[0] == EVTCHNOP_send)
+ handled = kvm_xen_hcall_evtchn_send(vcpu, params[1], &r);
+ break;
+
+ default:
+ break;
+ }
+
+ if (handled)
+ return kvm_xen_hypercall_set_result(vcpu, r);
+
vcpu->run->exit_reason = KVM_EXIT_XEN;
vcpu->run->xen.type = KVM_EXIT_XEN_HCALL;
vcpu->run->xen.u.hcall.longmode = longmode;
@@ -1124,6 +1138,213 @@ int kvm_xen_hvm_evtchn_send(struct kvm *kvm, struct kvm_irq_routing_xen_evtchn *
return ret;
}
+/*
+ * Support for *outbound* event channel events via the EVTCHNOP_send hypercall.
+ */
+struct evtchnfd {
+ u32 send_port;
+ u32 type;
+ union {
+ struct kvm_xen_evtchn port;
+ struct {
+ u32 port; /* zero */
+ struct eventfd_ctx *ctx;
+ } eventfd;
+ } deliver;
+};
+
+/*
+ * Update target vCPU or priority for a registered sending channel.
+ */
+static int kvm_xen_eventfd_update(struct kvm *kvm,
+ struct kvm_xen_hvm_attr *data)
+{
+ u32 port = data->u.evtchn.send_port;
+ struct evtchnfd *evtchnfd;
+
+ if (!port || port >= max_evtchn_port(kvm))
+ return -EINVAL;
+
+ mutex_lock(&kvm->lock);
+ evtchnfd = idr_find(&kvm->arch.xen.evtchn_ports, port);
+ mutex_unlock(&kvm->lock);
+
+ if (!evtchnfd)
+ return -ENOENT;
+
+ /* For an UPDATE, nothing may change except the priority/vcpu */
+ if (evtchnfd->type != data->u.evtchn.type)
+ return -EINVAL;
+
+ /*
+ * Port cannot change, and if it's zero that was an eventfd
+ * which can't be changed either.
+ */
+ if (!evtchnfd->deliver.port.port ||
+ evtchnfd->deliver.port.port != data->u.evtchn.deliver.port.port)
+ return -EINVAL;
+
+ /* We only support 2 level event channels for now */
+ if (data->u.evtchn.deliver.port.priority != KVM_IRQ_ROUTING_XEN_EVTCHN_PRIO_2LEVEL)
+ return -EINVAL;
+
+ mutex_lock(&kvm->lock);
+ evtchnfd->deliver.port.priority = data->u.evtchn.deliver.port.priority;
+ if (evtchnfd->deliver.port.vcpu_id != data->u.evtchn.deliver.port.vcpu) {
+ evtchnfd->deliver.port.vcpu_id = data->u.evtchn.deliver.port.vcpu;
+ evtchnfd->deliver.port.vcpu_idx = -1;
+ }
+ mutex_unlock(&kvm->lock);
+ return 0;
+}
+
+/*
+ * Configure the target (eventfd or local port delivery) for sending on
+ * a given event channel.
+ */
+static int kvm_xen_eventfd_assign(struct kvm *kvm,
+ struct kvm_xen_hvm_attr *data)
+{
+ u32 port = data->u.evtchn.send_port;
+ struct eventfd_ctx *eventfd = NULL;
+ struct evtchnfd *evtchnfd = NULL;
+ int ret = -EINVAL;
+
+ if (!port || port >= max_evtchn_port(kvm))
+ return -EINVAL;
+
+ evtchnfd = kzalloc(sizeof(struct evtchnfd), GFP_KERNEL);
+ if (!evtchnfd)
+ return -ENOMEM;
+
+ switch(data->u.evtchn.type) {
+ case EVTCHNSTAT_ipi:
+ /* IPI must map back to the same port# */
+ if (data->u.evtchn.deliver.port.port != data->u.evtchn.send_port)
+ goto out; /* -EINVAL */
+ break;
+
+ case EVTCHNSTAT_interdomain:
+ if (data->u.evtchn.deliver.port.port) {
+ if (data->u.evtchn.deliver.port.port >= max_evtchn_port(kvm))
+ goto out; /* -EINVAL */
+ } else {
+ eventfd = eventfd_ctx_fdget(data->u.evtchn.deliver.eventfd.fd);
+ if (IS_ERR(eventfd)) {
+ ret = PTR_ERR(eventfd);
+ goto out;
+ }
+ }
+ break;
+
+ case EVTCHNSTAT_virq:
+ case EVTCHNSTAT_closed:
+ case EVTCHNSTAT_unbound:
+ case EVTCHNSTAT_pirq:
+ default: /* Unknown event channel type */
+ goto out; /* -EINVAL */
+ }
+
+ evtchnfd->type = data->u.evtchn.type;
+ if (eventfd) {
+ evtchnfd->deliver.eventfd.ctx = eventfd;
+ } else {
+ /* We only support 2 level event channels for now */
+ if (data->u.evtchn.deliver.port.priority != KVM_IRQ_ROUTING_XEN_EVTCHN_PRIO_2LEVEL)
+ goto out; /* -EINVAL; */
+
+ evtchnfd->deliver.port.port = data->u.evtchn.deliver.port.port;
+ evtchnfd->deliver.port.vcpu_id = data->u.evtchn.deliver.port.vcpu;
+ evtchnfd->deliver.port.vcpu_idx = -1;
+ evtchnfd->deliver.port.priority = data->u.evtchn.deliver.port.priority;
+ }
+
+ mutex_lock(&kvm->lock);
+ ret = idr_alloc(&kvm->arch.xen.evtchn_ports, evtchnfd, port, port + 1,
+ GFP_KERNEL);
+ mutex_unlock(&kvm->lock);
+
+ if (ret >= 0)
+ return 0;
+
+ if (ret == -ENOSPC)
+ ret = -EEXIST;
+out:
+ if (eventfd)
+ eventfd_ctx_put(eventfd);
+ kfree(evtchnfd);
+ return ret;
+}
+
+static int kvm_xen_eventfd_deassign(struct kvm *kvm, u32 port)
+{
+ struct evtchnfd *evtchnfd;
+
+ mutex_lock(&kvm->lock);
+ evtchnfd = idr_remove(&kvm->arch.xen.evtchn_ports, port);
+ mutex_unlock(&kvm->lock);
+
+ if (!evtchnfd)
+ return -ENOENT;
+
+ if (kvm)
+ synchronize_srcu(&kvm->srcu);
+ if (!evtchnfd->deliver.port.port)
+ eventfd_ctx_put(evtchnfd->deliver.eventfd.ctx);
+ kfree(evtchnfd);
+ return 0;
+}
+
+static int kvm_xen_setattr_evtchn(struct kvm *kvm, struct kvm_xen_hvm_attr *data)
+{
+ u32 port = data->u.evtchn.send_port;
+
+ if (!port || port >= max_evtchn_port(kvm))
+ return -EINVAL;
+
+ if (data->u.evtchn.flags == KVM_XEN_EVTCHN_DEASSIGN)
+ return kvm_xen_eventfd_deassign(kvm, port);
+ if (data->u.evtchn.flags == KVM_XEN_EVTCHN_UPDATE)
+ return kvm_xen_eventfd_update(kvm, data);
+ if (data->u.evtchn.flags)
+ return -EINVAL;
+
+ return kvm_xen_eventfd_assign(kvm, data);
+}
+
+static bool kvm_xen_hcall_evtchn_send(struct kvm_vcpu *vcpu, u64 param, u64 *r)
+{
+ struct evtchnfd *evtchnfd;
+ struct evtchn_send send;
+ gpa_t gpa;
+ int idx;
+
+ idx = srcu_read_lock(&vcpu->kvm->srcu);
+ gpa = kvm_mmu_gva_to_gpa_system(vcpu, param, NULL);
+ srcu_read_unlock(&vcpu->kvm->srcu, idx);
+
+ if (!gpa || kvm_vcpu_read_guest(vcpu, gpa, &send, sizeof(send))) {
+ *r = -EFAULT;
+ return true;
+ }
+
+ /* The evtchn_ports idr is protected by vcpu->kvm->srcu */
+ evtchnfd = idr_find(&vcpu->kvm->arch.xen.evtchn_ports, send.port);
+ if (!evtchnfd)
+ return false;
+
+ if (evtchnfd->deliver.port.port) {
+ int ret = kvm_xen_set_evtchn(&evtchnfd->deliver.port, vcpu->kvm);
+ if (ret < 0 && ret != -ENOTCONN)
+ return false;
+ } else {
+ eventfd_signal(evtchnfd->deliver.eventfd.ctx, 1);
+ }
+
+ *r = 0;
+ return true;
+}
+
void kvm_xen_destroy_vcpu(struct kvm_vcpu *vcpu)
{
kvm_gfn_to_pfn_cache_destroy(vcpu->kvm,
@@ -1135,3 +1356,26 @@ void kvm_xen_destroy_vcpu(struct kvm_vcpu *vcpu)
kvm_gfn_to_pfn_cache_destroy(vcpu->kvm,
&vcpu->arch.xen.vcpu_time_info_cache);
}
+
+void kvm_xen_init_vm(struct kvm *kvm)
+{
+ idr_init(&kvm->arch.xen.evtchn_ports);
+}
+
+void kvm_xen_destroy_vm(struct kvm *kvm)
+{
+ struct evtchnfd *evtchnfd;
+ int i;
+
+ kvm_gfn_to_pfn_cache_destroy(kvm, &kvm->arch.xen.shinfo_cache);
+
+ idr_for_each_entry(&kvm->arch.xen.evtchn_ports, evtchnfd, i) {
+ if (!evtchnfd->deliver.port.port)
+ eventfd_ctx_put(evtchnfd->deliver.eventfd.ctx);
+ kfree(evtchnfd);
+ }
+ idr_destroy(&kvm->arch.xen.evtchn_ports);
+
+ if (kvm->arch.xen_hvm_config.msr)
+ static_branch_slow_dec_deferred(&kvm_xen_enabled);
+}
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 5b10e43e294c..9f4150d857e0 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1676,6 +1676,31 @@ struct kvm_xen_hvm_attr {
struct {
__u64 gfn;
} shared_info;
+ struct {
+ __u32 send_port;
+ __u32 type; /* EVTCHNSTAT_ipi / EVTCHNSTAT_interdomain */
+ __u32 flags;
+#define KVM_XEN_EVTCHN_DEASSIGN (1 << 0)
+#define KVM_XEN_EVTCHN_UPDATE (1 << 1)
+ /*
+ * Events sent by the guest are either looped back to
+ * the guest itself (potentially on a different port#)
+ * or signalled via an eventfd.
+ */
+ union {
+ struct {
+ __u32 port;
+ __u32 vcpu;
+ __u32 priority;
+ } port;
+ struct {
+ __u32 port; /* Zero for eventfd */
+ __s32 fd;
+ } eventfd;
+ __u32 padding[4];
+ } deliver;
+ } evtchn;
+
__u64 pad[8];
} u;
};
@@ -1684,6 +1709,8 @@ struct kvm_xen_hvm_attr {
#define KVM_XEN_ATTR_TYPE_LONG_MODE 0x0
#define KVM_XEN_ATTR_TYPE_SHARED_INFO 0x1
#define KVM_XEN_ATTR_TYPE_UPCALL_VECTOR 0x2
+/* Available with KVM_CAP_XEN_HVM / KVM_XEN_HVM_CONFIG_EVTCHN_SEND */
+#define KVM_XEN_ATTR_TYPE_EVTCHN 0x3
/* Per-vCPU Xen attributes */
#define KVM_XEN_VCPU_GET_ATTR _IOWR(KVMIO, 0xca, struct kvm_xen_vcpu_attr)
--
2.33.1
