[RFC PATCH v3 14/17] kvm: Add VBUS support to the host

Gregory Haskins
2009-04-21T18:44:01Z

This patch adds support for guest access to a VBUS assigned to the same
context as the VM. It utilizes a IOQ+IRQ to move events from host->guest,
and provides a hypercall interface to move events guest->host.

Special thanks to Alex Tsariounov for submitting patches for cleaning
up some sloppy warnings I had left in the code.

Signed-off-by: Gregory Haskins <ghaskins@novell.com>
---

arch/x86/include/asm/kvm_para.h | 1
arch/x86/kvm/Kconfig | 9
arch/x86/kvm/Makefile | 3
arch/x86/kvm/x86.c | 6
arch/x86/kvm/x86.h | 12
include/linux/kvm.h | 7
include/linux/kvm_host.h | 26 +
include/linux/kvm_para.h | 58 ++
virt/kvm/kvm_main.c | 10
virt/kvm/vbus.c | 1392 +++++++++++++++++++++++++++++++++++++++
10 files changed, 1524 insertions(+), 0 deletions(-)
create mode 100644 virt/kvm/vbus.c

diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h
index b8a3305..0a209b4 100644
--- a/arch/x86/include/asm/kvm_para.h
+++ b/arch/x86/include/asm/kvm_para.h
@@ -13,6 +13,7 @@
#define KVM_FEATURE_CLOCKSOURCE 0
#define KVM_FEATURE_NOP_IO_DELAY 1
#define KVM_FEATURE_MMU_OP 2
+#define KVM_FEATURE_VBUS 3

#define MSR_KVM_WALL_CLOCK 0x11
#define MSR_KVM_SYSTEM_TIME 0x12
diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
index a58504e..f2bcb4f 100644
--- a/arch/x86/kvm/Kconfig
+++ b/arch/x86/kvm/Kconfig
@@ -69,6 +69,15 @@ config KVM_TRACE
relayfs. Note the ABI is not considered stable and will be
modified in future updates.

+config KVM_HOST_VBUS
+ bool "KVM virtual-bus (VBUS) host-side support"
+ depends on KVM
+ select VBUS
+ default n
+ ---help---
+ This option enables host-side support for accessing virtual-bus
+ devices.
+
# OK, it's a little counter-intuitive to do this, but it puts it neatly under
# the virtualization menu.
source drivers/lguest/Kconfig
diff --git a/arch/x86/kvm/Makefile b/arch/x86/kvm/Makefile
index d3ec292..32ffe5b 100644
--- a/arch/x86/kvm/Makefile
+++ b/arch/x86/kvm/Makefile
@@ -15,6 +15,9 @@ EXTRA_CFLAGS += -Ivirt/kvm -Iarch/x86/kvm

kvm-objs := $(common-objs) x86.o mmu.o x86_emulate.o i8259.o irq.o lapic.o \
i8254.o
+ifeq ($(CONFIG_KVM_HOST_VBUS),y)
+kvm-objs += $(addprefix ../../../virt/kvm/, vbus.o)
+endif
obj-$(CONFIG_KVM) += kvm.o
kvm-intel-objs = vmx.o
obj-$(CONFIG_KVM_INTEL) += kvm-intel.o
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 8ca100a..9f4895e 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1040,6 +1040,9 @@ int kvm_dev_ioctl_check_extension(long ext)
case KVM_CAP_IOMMU:
r = iommu_found();
break;
+ case KVM_CAP_VBUS:
+ r = kvm_vbus_support();
+ break;
default:
r = 0;
break;
@@ -2830,6 +2833,9 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
case KVM_HC_MMU_OP:
r = kvm_pv_mmu_op(vcpu, a0, hc_gpa(vcpu, a1, a2), &ret);
break;
+ case KVM_HC_VBUS:
+ ret = kvm_vbus_hc(vcpu, a0, a1, a2);
+ break;
default:
ret = -KVM_ENOSYS;
break;
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index 6a4be78..b6c682b 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -3,6 +3,18 @@

#include <linux/kvm_host.h>

+#ifdef CONFIG_KVM_HOST_VBUS
+static inline int kvm_vbus_support(void)
+{
+ return 1;
+}
+#else
+static inline int kvm_vbus_support(void)
+{
+ return 0;
+}
+#endif
+
static inline void kvm_clear_exception_queue(struct kvm_vcpu *vcpu)
{
vcpu->arch.exception.pending = false;
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index 311a073..9b83bbc 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -409,6 +409,7 @@ struct kvm_trace_rec {
#ifdef __KVM_HAVE_DEVICE_ASSIGNMENT
#define KVM_CAP_DEVICE_DEASSIGNMENT 27
#endif
+#define KVM_CAP_VBUS 28

#ifdef KVM_CAP_IRQ_ROUTING

@@ -448,6 +449,11 @@ struct kvm_irq_routing {

#endif

+struct kvm_vbus_gsi {
+ __u32 queue;
+ __u32 gsi;
+};
+
/*
* ioctls for VM fds
*/
@@ -485,6 +491,7 @@ struct kvm_irq_routing {
#define KVM_REINJECT_CONTROL _IO(KVMIO, 0x71)
#define KVM_DEASSIGN_PCI_DEVICE _IOW(KVMIO, 0x72, \
struct kvm_assigned_pci_dev)
+#define KVM_VBUS_ASSIGN_GSI _IOW(KVMIO, 0x73, struct kvm_vbus_gsi)

/*
* ioctls for vcpu fds
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 894a56e..43c310c 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -134,6 +134,9 @@ struct kvm {
struct list_head vm_list;
struct kvm_io_bus mmio_bus;
struct kvm_io_bus pio_bus;
+#ifdef CONFIG_KVM_HOST_VBUS
+ struct kvm_vbus *kvbus;
+#endif
struct kvm_vm_stat stat;
struct kvm_arch arch;
atomic_t users_count;
@@ -512,4 +515,27 @@ static inline void kvm_free_irq_routing(struct kvm *kvm) {}

#endif

+#ifdef CONFIG_KVM_HOST_VBUS
+
+int kvm_vbus_hc(struct kvm_vcpu *vcpu, int nr, gpa_t gpa, size_t len);
+void kvm_vbus_release(struct kvm_vbus *kvbus);
+int kvm_vbus_assign_gsi(struct kvm *kvm, int queue, int gsi);
+
+#else /* CONFIG_KVM_HOST_VBUS */
+
+static inline int
+kvm_vbus_hc(struct kvm_vcpu *vcpu, int nr, gpa_t gpa, size_t len)
+{
+ return -EINVAL;
+}
+
+#define kvm_vbus_release(kvbus) do {} while (0)
+
+static inline int kvm_vbus_assign_gsi(struct kvm *kvm, int queue, int gsi)
+{
+ return -EINVAL;
+}
+
+#endif /* CONFIG_KVM_HOST_VBUS */
+
#endif
diff --git a/include/linux/kvm_para.h b/include/linux/kvm_para.h
index 3ddce03..7932aa3 100644
--- a/include/linux/kvm_para.h
+++ b/include/linux/kvm_para.h
@@ -16,6 +16,64 @@

#define KVM_HC_VAPIC_POLL_IRQ 1
#define KVM_HC_MMU_OP 2
+#define KVM_HC_VBUS 3
+
+/* Payload of KVM_HC_VBUS */
+#define KVM_VBUS_MAGIC 0x27fdab45
+#define KVM_VBUS_VERSION 1
+
+enum kvm_vbus_op{
+ KVM_VBUS_OP_BUSOPEN,
+ KVM_VBUS_OP_BUSREG,
+ KVM_VBUS_OP_DEVOPEN,
+ KVM_VBUS_OP_DEVCLOSE,
+ KVM_VBUS_OP_DEVCALL,
+ KVM_VBUS_OP_DEVSHM,
+ KVM_VBUS_OP_SHMSIGNAL,
+};
+
+struct kvm_vbus_busopen {
+ __u32 magic;
+ __u32 version;
+ __u64 capabilities;
+};
+
+struct kvm_vbus_eventqreg {
+ __u32 count;
+ __u64 ring;
+ __u64 data;
+};
+
+struct kvm_vbus_busreg {
+ __u32 count; /* supporting multiple queues allows for prio, etc */
+ struct kvm_vbus_eventqreg eventq[1];
+};
+
+enum kvm_vbus_eventid {
+ KVM_VBUS_EVENT_DEVADD,
+ KVM_VBUS_EVENT_DEVDROP,
+ KVM_VBUS_EVENT_SHMSIGNAL,
+ KVM_VBUS_EVENT_SHMCLOSE,
+};
+
+#define VBUS_MAX_DEVTYPE_LEN 128
+
+struct kvm_vbus_add_event {
+ __u64 id;
+ char type[VBUS_MAX_DEVTYPE_LEN];
+};
+
+struct kvm_vbus_handle_event {
+ __u64 handle;
+};
+
+struct kvm_vbus_event {
+ __u32 eventid;
+ union {
+ struct kvm_vbus_add_event add;
+ struct kvm_vbus_handle_event handle;
+ } data;
+};

/*
* hypercalls use architecture specific
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 605697e..5373402 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -901,6 +901,7 @@ static int kvm_vm_release(struct inode *inode, struct file *filp)
{
struct kvm *kvm = filp->private_data;

+ kvm_vbus_release(kvm->kvbus);
kvm_put_kvm(kvm);
return 0;
}
@@ -1920,6 +1921,15 @@ static long kvm_vm_ioctl(struct file *filp,
break;
}
#endif
+ case KVM_VBUS_ASSIGN_GSI: {
+ struct kvm_vbus_gsi data;
+
+ r = -EFAULT;
+ if (copy_from_user(&data, argp, sizeof data))
+ goto out;
+ r = kvm_vbus_assign_gsi(kvm, data.queue, data.gsi);
+ break;
+ }
default:
r = kvm_arch_vm_ioctl(filp, ioctl, arg);
}
diff --git a/virt/kvm/vbus.c b/virt/kvm/vbus.c
new file mode 100644
index 0000000..cf0d167
--- /dev/null
+++ b/virt/kvm/vbus.c
@@ -0,0 +1,1392 @@
+/*
+ * Copyright 2009 Novell. All Rights Reserved.
+ *
+ * Author:
+ * Gregory Haskins <ghaskins@novell.com>
+ *
+ * This file is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#include <linux/module.h>
+#include <linux/rbtree.h>
+#include <linux/spinlock.h>
+#include <linux/highmem.h>
+#include <linux/workqueue.h>
+#include <linux/completion.h>
+#include <linux/mm.h>
+#include <linux/vmalloc.h>
+#include <linux/ioq.h>
+
+#include <linux/kvm.h>
+#include <linux/kvm_host.h>
+#include <linux/kvm_para.h>
+#include <linux/vbus.h>
+#include <linux/vbus_client.h>
+
+#undef PDEBUG
+#ifdef KVMVBUS_DEBUG
+#include <linux/ftrace.h>
+# define PDEBUG(fmt, args...) ftrace_printk(fmt, ## args)
+#else
+# define PDEBUG(fmt, args...)
+#endif
+
+#define EVENTQ_COUNT 8
+
+struct kvm_vbus_eventq {
+ spinlock_t lock;
+ int prio;
+ struct ioq *ioq;
+ struct ioq_notifier notifier;
+ struct vbus_shm *shm;
+ struct shm_signal signal;
+ int gsi;
+ struct list_head backlog;
+ struct {
+ u64 gpa;
+ size_t len;
+ void *ptr;
+ } ringdata;
+ struct work_struct wakeup;
+ struct work_struct inject;
+ int backpressure:1;
+ int active:1;
+};
+
+enum kvm_vbus_state {
+ kvm_vbus_state_init,
+ kvm_vbus_state_registration,
+ kvm_vbus_state_running,
+};
+
+struct kvm_vbus {
+ atomic_t refs;
+ struct completion free;
+ struct mutex lock;
+ enum kvm_vbus_state state;
+ struct kvm *kvm;
+ struct vbus *vbus;
+ struct vbus_client *client;
+ struct {
+ int count;
+ struct kvm_vbus_eventq queues[EVENTQ_COUNT];
+ } eventq;
+ struct vbus_memctx *ctx;
+ int irqsrc;
+ struct notifier_block vbusnotify;
+};
+
+static inline struct kvm_vbus *
+kvm_vbus_get(struct kvm_vbus *kvbus)
+{
+ atomic_inc(&kvbus->refs);
+
+ return kvbus;
+}
+
+static inline void
+kvm_vbus_put(struct kvm_vbus *kvbus)
+{
+ if (atomic_dec_and_test(&kvbus->refs))
+ complete(&kvbus->free);
+}
+
+struct vbus_client *to_client(struct kvm_vcpu *vcpu)
+{
+ return vcpu ? vcpu->kvm->kvbus->client : NULL;
+}
+
+static void*
+kvm_vmap(struct kvm *kvm, gpa_t gpa, size_t len)
+{
+ struct page **page_list;
+ void *ptr = NULL;
+ unsigned long addr;
+ off_t offset;
+ size_t npages;
+ int ret;
+
+ addr = gfn_to_hva(kvm, gpa >> PAGE_SHIFT);
+
+ offset = offset_in_page(gpa);
+ npages = PAGE_ALIGN(len + offset) >> PAGE_SHIFT;
+
+ if (npages > (PAGE_SIZE / sizeof(struct page *)))
+ return NULL;
+
+ page_list = (struct page **) __get_free_page(GFP_KERNEL);
+ if (!page_list)
+ return NULL;
+
+ ret = get_user_pages_fast(addr, npages, 1, page_list);
+ if (ret < 0)
+ goto out;
+
+ down_write(&current->mm->mmap_sem);
+
+ ptr = vmap(page_list, npages, VM_MAP, PAGE_KERNEL);
+ if (ptr)
+ current->mm->locked_vm += npages;
+
+ up_write(&current->mm->mmap_sem);
+
+ ptr = ptr+offset;
+
+out:
+ free_page((unsigned long)page_list);
+
+ return ptr;
+}
+
+static void
+kvm_vunmap(void *ptr)
+{
+ /* FIXME: do we need to adjust current->mm->locked_vm? */
+ vunmap((void *)((unsigned long)ptr & PAGE_MASK));
+}
+
+/*
+ * -----------------
+ * kvm_shm routines
+ * -----------------
+ */
+
+struct kvm_shm {
+ struct kvm_vbus *kvbus;
+ struct vbus_shm shm;
+};
+
+static void
+kvm_shm_release(struct vbus_shm *shm)
+{
+ struct kvm_shm *_shm = container_of(shm, struct kvm_shm, shm);
+
+ kvm_vunmap(_shm->shm.ptr);
+ kfree(_shm);
+}
+
+static struct vbus_shm_ops kvm_shm_ops = {
+ .release = kvm_shm_release,
+};
+
+static int
+kvm_shm_map(struct kvm_vbus *kvbus, __u64 ptr, __u32 len, struct kvm_shm **kshm)
+{
+ struct kvm_shm *_shm;
+ void *vmap;
+
+ if (!can_do_mlock())
+ return -EPERM;
+
+ _shm = kzalloc(sizeof(*_shm), GFP_KERNEL);
+ if (!_shm)
+ return -ENOMEM;
+
+ _shm->kvbus = kvbus;
+
+ vmap = kvm_vmap(kvbus->kvm, ptr, len);
+ if (!vmap) {
+ kfree(_shm);
+ return -EFAULT;
+ }
+
+ vbus_shm_init(&_shm->shm, &kvm_shm_ops, vmap, len);
+
+ *kshm = _shm;
+
+ return 0;
+}
+
+/*
+ * -----------------
+ * vbus_memctx routines
+ * -----------------
+ */
+
+struct kvm_memctx {
+ struct kvm *kvm;
+ struct vbus_memctx *taskmem;
+ struct vbus_memctx ctx;
+};
+
+static struct kvm_memctx *to_kvm_memctx(struct vbus_memctx *ctx)
+{
+ return container_of(ctx, struct kvm_memctx, ctx);
+}
+
+
+static unsigned long
+kvm_memctx_copy_to(struct vbus_memctx *ctx, void *dst, const void *src,
+ unsigned long n)
+{
+ struct kvm_memctx *kvm_memctx = to_kvm_memctx(ctx);
+ struct vbus_memctx *tm = kvm_memctx->taskmem;
+ gpa_t gpa = (gpa_t)dst;
+ unsigned long addr;
+ int offset;
+
+ addr = gfn_to_hva(kvm_memctx->kvm, gpa >> PAGE_SHIFT);
+ offset = offset_in_page(gpa);
+
+ return tm->ops->copy_to(tm, (void *)(addr + offset), src, n);
+}
+
+static unsigned long
+kvm_memctx_copy_from(struct vbus_memctx *ctx, void *dst, const void *src,
+ unsigned long n)
+{
+ struct kvm_memctx *kvm_memctx = to_kvm_memctx(ctx);
+ struct vbus_memctx *tm = kvm_memctx->taskmem;
+ gpa_t gpa = (gpa_t)src;
+ unsigned long addr;
+ int offset;
+
+ addr = gfn_to_hva(kvm_memctx->kvm, gpa >> PAGE_SHIFT);
+ offset = offset_in_page(gpa);
+
+ return tm->ops->copy_from(tm, dst, (void *)(addr + offset), n);
+}
+
+static void
+kvm_memctx_release(struct vbus_memctx *ctx)
+{
+ struct kvm_memctx *kvm_memctx = to_kvm_memctx(ctx);
+
+ vbus_memctx_put(kvm_memctx->taskmem);
+ kvm_put_kvm(kvm_memctx->kvm);
+
+ kfree(kvm_memctx);
+}
+
+static struct vbus_memctx_ops kvm_memctx_ops = {
+ .copy_to = &kvm_memctx_copy_to,
+ .copy_from = &kvm_memctx_copy_from,
+ .release = &kvm_memctx_release,
+};
+
+struct vbus_memctx *kvm_memctx_alloc(struct kvm *kvm)
+{
+ struct kvm_memctx *kvm_memctx;
+
+ kvm_memctx = kzalloc(sizeof(*kvm_memctx), GFP_KERNEL);
+ if (!kvm_memctx)
+ return NULL;
+
+ kvm_get_kvm(kvm);
+ kvm_memctx->kvm = kvm;
+
+ kvm_memctx->taskmem = task_memctx_alloc(current);
+ vbus_memctx_init(&kvm_memctx->ctx, &kvm_memctx_ops);
+
+ return &kvm_memctx->ctx;
+}
+
+/*
+ * -----------------
+ * general routines
+ * -----------------
+ */
+
+static int
+_signal_init(struct kvm *kvm, struct shm_signal_desc *desc,
+ struct shm_signal *signal, struct shm_signal_ops *ops)
+{
+ if (desc->magic != SHM_SIGNAL_MAGIC)
+ return -EINVAL;
+
+ if (desc->ver != SHM_SIGNAL_VER)
+ return -EINVAL;
+
+ shm_signal_init(signal);
+
+ signal->locale = shm_locality_south;
+ signal->ops = ops;
+ signal->desc = desc;
+
+ return 0;
+}
+
+static struct kvm_vbus_event *
+event_ptr_translate(struct kvm_vbus_eventq *eventq, u64 ptr)
+{
+ u64 off = ptr - eventq->ringdata.gpa;
+
+ if ((ptr < eventq->ringdata.gpa)
+ || (off > (eventq->ringdata.len - sizeof(struct kvm_vbus_event))))
+ return NULL;
+
+ return eventq->ringdata.ptr + off;
+}
+
+/*
+ * ------------------
+ * event-object code
+ * ------------------
+ */
+
+struct _event {
+ atomic_t refs;
+ struct list_head list;
+ struct kvm_vbus_event data;
+};
+
+static void
+_event_init(struct _event *event)
+{
+ memset(event, 0, sizeof(*event));
+ atomic_set(&event->refs, 1);
+ INIT_LIST_HEAD(&event->list);
+}
+
+static void
+_event_get(struct _event *event)
+{
+ atomic_inc(&event->refs);
+}
+
+static inline void
+_event_put(struct _event *event)
+{
+ if (atomic_dec_and_test(&event->refs))
+ kfree(event);
+}
+
+/*
+ * ------------------
+ * event-inject code
+ * ------------------
+ */
+
+static struct kvm_vbus_eventq *notify_to_eventq(struct ioq_notifier *notifier)
+{
+ return container_of(notifier, struct kvm_vbus_eventq, notifier);
+}
+
+static struct kvm_vbus_eventq *signal_to_eventq(struct shm_signal *signal)
+{
+ return container_of(signal, struct kvm_vbus_eventq, signal);
+}
+
+static struct kvm_vbus *eventq_to_bus(struct kvm_vbus_eventq *eventq)
+{
+ return container_of(eventq, struct kvm_vbus,
+ eventq.queues[eventq->prio]);
+}
+
+
+/*
+ * This is invoked by the guest whenever they signal our eventq when
+ * we have notifications enabled
+ */
+static void
+eventq_notify(struct ioq_notifier *notifier)
+{
+ struct kvm_vbus_eventq *eventq = notify_to_eventq(notifier);
+ unsigned long flags;
+
+ spin_lock_irqsave(&eventq->lock, flags);
+
+ if (eventq->ioq && !ioq_full(eventq->ioq, ioq_idxtype_inuse)) {
+ eventq->backpressure = false;
+ ioq_notify_disable(eventq->ioq, 0);
+ schedule_work(&eventq->wakeup);
+ }
+
+ spin_unlock_irqrestore(&eventq->lock, flags);
+}
+
+static void
+events_flush(struct kvm_vbus_eventq *eventq)
+{
+ struct ioq_iterator iter;
+ int ret;
+ unsigned long flags;
+ struct _event *_event, *tmp;
+ int dirty = 0;
+ struct ioq *ioq = NULL;
+
+ spin_lock_irqsave(&eventq->lock, flags);
+
+ if (!eventq->ioq) {
+ spin_unlock_irqrestore(&eventq->lock, flags);
+ return;
+ }
+
+ /* We want to iterate on the tail of the in-use index */
+ ret = ioq_iter_init(eventq->ioq, &iter, ioq_idxtype_inuse, 0);
+ BUG_ON(ret < 0);
+
+ ret = ioq_iter_seek(&iter, ioq_seek_tail, 0, 0);
+ BUG_ON(ret < 0);
+
+ list_for_each_entry_safe(_event, tmp, &eventq->backlog, list) {
+ struct kvm_vbus_event *ev;
+
+ if (!iter.desc->sown) {
+ eventq->backpressure = true;
+ ioq_notify_enable(eventq->ioq, 0);
+ break;
+ }
+
+ if (iter.desc->len < sizeof(*ev)) {
+ SHM_SIGNAL_FAULT(eventq->ioq->signal,
+ "Desc too small on eventq: %p: %ld<%ld",
+ (void*)iter.desc->ptr,
+ (unsigned long)iter.desc->len, sizeof(*ev));
+ break;
+ }
+
+ ev = event_ptr_translate(eventq, iter.desc->ptr);
+ if (!ev) {
+ SHM_SIGNAL_FAULT(eventq->ioq->signal,
+ "Invalid address on eventq: %p",
+ (void*)iter.desc->ptr);
+ break;
+ }
+
+ memcpy(ev, &_event->data, sizeof(*ev));
+
+ list_del_init(&_event->list);
+ _event_put(_event);
+
+ ret = ioq_iter_push(&iter, 0);
+ BUG_ON(ret < 0);
+
+ dirty = 1;
+ }
+
+ if (dirty)
+ ioq = ioq_get(eventq->ioq);
+
+ spin_unlock_irqrestore(&eventq->lock, flags);
+
+ /*
+ * Signal the IOQ outside of the spinlock so that we can potentially
+ * directly inject this interrupt instead of deferring it
+ */
+ if (ioq) {
+ ioq_signal(ioq, 0);
+ ioq_put(ioq);
+ }
+}
+
+static int
+event_inject(struct kvm_vbus_eventq *eventq, struct _event *_event)
+{
+ unsigned long flags;
+
+ if (!list_empty(&_event->list))
+ return -EBUSY;
+
+ spin_lock_irqsave(&eventq->lock, flags);
+ list_add_tail(&_event->list, &eventq->backlog);
+ spin_unlock_irqrestore(&eventq->lock, flags);
+
+ events_flush(eventq);
+
+ return 0;
+}
+
+static void
+eventq_reinject(struct work_struct *work)
+{
+ struct kvm_vbus_eventq *eventq;
+
+ eventq = container_of(work, struct kvm_vbus_eventq, wakeup);
+
+ events_flush(eventq);
+}
+
+/*
+ * devadd/drop are in the slow path and are rare enough that we will
+ * simply allocate memory for the event from the heap
+ */
+static int
+devadd_inject(struct kvm_vbus_eventq *eventq, const char *type, u64 id)
+{
+ struct _event *_event;
+ struct kvm_vbus_add_event *ae;
+ int ret;
+
+ _event = kmalloc(sizeof(*_event), GFP_KERNEL);
+ if (!_event)
+ return -ENOMEM;
+
+ _event_init(_event);
+
+ _event->data.eventid = KVM_VBUS_EVENT_DEVADD;
+ ae = (struct kvm_vbus_add_event *)&_event->data.data;
+ ae->id = id;
+ strncpy(ae->type, type, VBUS_MAX_DEVTYPE_LEN);
+
+ ret = event_inject(eventq, _event);
+ if (ret < 0)
+ _event_put(_event);
+
+ return ret;
+}
+
+/*
+ * "handle" events are used to send any kind of event that simply
+ * uses a handle as a parameter. This includes things like DEVDROP
+ * and SHMSIGNAL, etc.
+ */
+static struct _event *
+handle_event_alloc(u64 id, u64 handle)
+{
+ struct _event *_event;
+ struct kvm_vbus_handle_event *he;
+
+ _event = kmalloc(sizeof(*_event), GFP_KERNEL);
+ if (!_event)
+ return NULL;
+
+ _event_init(_event);
+ _event->data.eventid = id;
+
+ he = (struct kvm_vbus_handle_event *)&_event->data.data;
+ he->handle = handle;
+
+ return _event;
+}
+
+static int
+devdrop_inject(struct kvm_vbus_eventq *eventq, u64 id)
+{
+ struct _event *_event;
+ int ret;
+
+ _event = handle_event_alloc(KVM_VBUS_EVENT_DEVDROP, id);
+ if (!_event)
+ return -ENOMEM;
+
+ ret = event_inject(eventq, _event);
+ if (ret < 0)
+ _event_put(_event);
+
+ return ret;
+}
+
+static struct kvm_vbus_eventq *
+prio_to_eventq(struct kvm_vbus *kvbus, int prio)
+{
+ int real_prio = min(prio, kvbus->eventq.count-1);
+
+ return &kvbus->eventq.queues[real_prio];
+}
+
+/*
+ * -----------------
+ * event ioq
+ *
+ * This queue is used by the infrastructure to transmit events (such as
+ * "new device", or "signal an ioq") to the guest. We do this so that
+ * we minimize the number of hypercalls required to inject an event.
+ * In theory, the guest only needs to process a single interrupt vector
+ * and it doesnt require switching back to host context since the state
+ * is placed within the ring
+ * -----------------
+ */
+
+static void
+_eventq_signal_inject(struct kvm_vbus_eventq *eventq)
+{
+ struct kvm_vbus *kvbus = eventq_to_bus(eventq);
+ struct kvm *kvm = kvbus->kvm;
+
+ /* Inject an interrupt to the guest */
+ if (eventq->gsi) {
+ mutex_lock(&kvm->lock);
+ kvm_set_irq(kvm, kvbus->irqsrc, eventq->gsi, 1);
+ mutex_unlock(&kvm->lock);
+ }
+}
+
+static void
+eventq_deferred_inject(struct work_struct *work)
+{
+ struct kvm_vbus_eventq *eventq;
+
+ eventq = container_of(work, struct kvm_vbus_eventq, inject);
+
+ _eventq_signal_inject(eventq);
+}
+
+/*
+ * We need to take the kvm->lock before we can actually inject an interrupt
+ * to the guest. Therefore, we check to see if this is executed in a
+ * preemptible context, which means it is safe to take a mutex. If it
+ * is not preemptible, it either means that we are truly not preemptible
+ * and therefore must defer. Or it means we are in a non-preemptible
+ * kernel, and simply cannot tell. Perhaps someday someone will provide
+ * an api that can discern the context state without relying on
+ * CONFIG_PREEMPT, but until then this will suffice.
+ */
+static int
+eventq_signal_inject(struct shm_signal *signal)
+{
+ struct kvm_vbus_eventq *eventq = signal_to_eventq(signal);
+
+ if (preemptible())
+ _eventq_signal_inject(eventq);
+ else
+ schedule_work(&eventq->inject);
+
+ return 0;
+}
+
+static void
+eventq_signal_release(struct shm_signal *signal)
+{
+ struct kvm_vbus_eventq *eventq = signal_to_eventq(signal);
+ struct kvm_vbus *kvbus = eventq_to_bus(eventq);
+
+ eventq->active = false;
+
+ flush_work(&eventq->wakeup);
+ flush_work(&eventq->inject);
+
+ vbus_shm_put(eventq->shm);
+ eventq->shm = NULL;
+
+ if (eventq->ringdata.ptr)
+ kvm_vunmap(eventq->ringdata.ptr);
+
+ kvm_vbus_put(kvbus);
+}
+
+static struct shm_signal_ops eventq_signal_ops = {
+ .inject = eventq_signal_inject,
+ .release = eventq_signal_release,
+};
+
+/*
+ * -----------------
+ * device_signal routines
+ *
+ * This is the more standard signal that is allocated to communicate
+ * with a specific device's shm region
+ * -----------------
+ */
+
+struct device_signal {
+ struct kvm_vbus *kvbus;
+ struct vbus_shm *shm;
+ struct shm_signal signal;
+ struct _event *inject;
+ int prio;
+ u64 handle;
+};
+
+static struct device_signal *to_dsig(struct shm_signal *signal)
+{
+ return container_of(signal, struct device_signal, signal);
+}
+
+static void
+_device_signal_inject(struct device_signal *_signal)
+{
+ struct kvm_vbus_eventq *eventq;
+ int ret;
+
+ eventq = prio_to_eventq(_signal->kvbus, _signal->prio);
+
+ ret = event_inject(eventq, _signal->inject);
+ if (ret < 0)
+ _event_put(_signal->inject);
+}
+
+static int
+device_signal_inject(struct shm_signal *signal)
+{
+ struct device_signal *_signal = to_dsig(signal);
+
+ _event_get(_signal->inject); /* will be dropped by injection code */
+ _device_signal_inject(_signal);
+
+ return 0;
+}
+
+static void
+device_signal_release(struct shm_signal *signal)
+{
+ struct device_signal *_signal = to_dsig(signal);
+ struct kvm_vbus_eventq *eventq;
+ unsigned long flags;
+
+ eventq = prio_to_eventq(_signal->kvbus, _signal->prio);
+
+ /*
+ * Change the event-type while holding the lock so we do not race
+ * with any potential threads already processing the queue
+ */
+ spin_lock_irqsave(&eventq->lock, flags);
+ _signal->inject->data.eventid = KVM_VBUS_EVENT_SHMCLOSE;
+ spin_unlock_irqrestore(&eventq->lock, flags);
+
+ /*
+ * do not take a reference to event..last will be dropped once
+ * transmitted.
+ */
+ _device_signal_inject(_signal);
+
+ vbus_shm_put(_signal->shm);
+ kvm_vbus_put(_signal->kvbus);
+ kfree(_signal);
+}
+
+static struct shm_signal_ops device_signal_ops = {
+ .inject = device_signal_inject,
+ .release = device_signal_release,
+};
+
+static int
+device_signal_alloc(struct kvm_vbus *kvbus, struct vbus_shm *shm,
+ u32 offset, u32 prio, u64 cookie,
+ struct device_signal **dsignal)
+{
+ struct device_signal *_signal;
+ int ret;
+
+ _signal = kzalloc(sizeof(*_signal), GFP_KERNEL);
+ if (!_signal)
+ return -ENOMEM;
+
+ ret = _signal_init(kvbus->kvm, shm->ptr + offset,
+ &_signal->signal,
+ &device_signal_ops);
+ if (ret < 0) {
+ kfree(_signal);
+ return ret;
+ }
+
+ _signal->kvbus = kvm_vbus_get(kvbus); /* released with the signal */
+
+ _signal->inject = handle_event_alloc(KVM_VBUS_EVENT_SHMSIGNAL, cookie);
+ if (!_signal->inject) {
+ shm_signal_put(&_signal->signal);
+ return -ENOMEM;
+ }
+
+ _signal->shm = shm;
+ _signal->prio = prio;
+ vbus_shm_get(shm); /* dropped when the signal is released */
+
+ *dsignal = _signal;
+
+ return 0;
+}
+
+/*
+ * ------------------
+ * notifiers
+ * ------------------
+ */
+
+/*
+ * This is called whenever our associated vbus emits an event. We inject
+ * these events at the highest logical priority
+ */
+static int
+vbus_notifier(struct notifier_block *nb, unsigned long nr, void *data)
+{
+ struct kvm_vbus *kvbus = container_of(nb, struct kvm_vbus, vbusnotify);
+ struct kvm_vbus_eventq *eventq = prio_to_eventq(kvbus, 7);
+
+ switch (nr) {
+ case VBUS_EVENT_DEVADD: {
+ struct vbus_event_devadd *ev = data;
+
+ devadd_inject(eventq, ev->type, ev->id);
+ break;
+ }
+ case VBUS_EVENT_DEVDROP: {
+ unsigned long id = *(unsigned long *)data;
+
+ devdrop_inject(eventq, id);
+ break;
+ }
+ default:
+ break;
+ }
+
+ return 0;
+}
+
+static void
+kvm_vbus_eventq_init(struct kvm_vbus_eventq *eventq, int prio)
+{
+ spin_lock_init(&eventq->lock);
+ eventq->prio = prio;
+ INIT_WORK(&eventq->wakeup, eventq_reinject);
+ INIT_WORK(&eventq->inject, eventq_deferred_inject);
+
+ eventq->notifier.signal = eventq_notify;
+
+ INIT_LIST_HEAD(&eventq->backlog);
+}
+
+static int
+kvm_vbus_eventq_attach(struct kvm_vbus *kvbus, struct kvm_vbus_eventq *eventq,
+ u32 count, u64 ring, u64 data)
+{
+ struct ioq_ring_head *desc;
+ struct ioq *ioq;
+ struct kvm_shm *_shm = NULL;
+ size_t len = IOQ_HEAD_DESC_SIZE(count);
+ void *ptr;
+ int ret;
+
+ if (eventq->active)
+ return -EINVAL;
+
+ ret = kvm_shm_map(kvbus, ring, len, &_shm);
+ if (ret < 0)
+ return ret;
+
+ desc = _shm->shm.ptr;
+
+ ret = _signal_init(kvbus->kvm,
+ &desc->signal,
+ &eventq->signal,
+ &eventq_signal_ops);
+ if (ret < 0) {
+ vbus_shm_put(&_shm->shm);
+ return ret;
+ }
+
+ eventq->shm = &_shm->shm; /* we hold the baseline ref already */
+ kvm_vbus_get(kvbus);
+
+ /* FIXME: we should make maxcount configurable */
+ ret = vbus_shm_ioq_attach(&_shm->shm, &eventq->signal, 2048, &ioq);
+ if (ret < 0) {
+ shm_signal_put(&eventq->signal);
+ vbus_shm_put(&_shm->shm);
+ return ret;
+ }
+
+ /*
+ * take refs for the successful ioq allocation, dropped when the
+ * signal releases.
+ */
+ vbus_shm_get(&_shm->shm);
+
+ /*
+ * We are going to pre-vmap the eventq data for performance reasons
+ *
+ * This will allow us to skip trying to demand load these particular
+ * pages in the fast-path, and it will also allow us to post writes
+ * from interrupt context (which would not be able to demand-load)
+ */
+ len = count * sizeof(struct kvm_vbus_event);
+ ptr = kvm_vmap(kvbus->kvm, data, len);
+ if (!ptr) {
+ ioq_put(ioq);
+ return -EFAULT;
+ }
+
+ ioq->notifier = &eventq->notifier;
+
+ eventq->ioq = ioq;
+ eventq->ringdata.len = len;
+ eventq->ringdata.gpa = data;
+ eventq->ringdata.ptr = ptr;
+
+ eventq->active = true;
+
+ return 0;
+}
+
+static void
+kvm_vbus_eventq_detach(struct kvm_vbus_eventq *eventq)
+{
+ struct ioq *ioq;
+ unsigned long flags;
+
+ spin_lock_irqsave(&eventq->lock, flags);
+
+ ioq = eventq->ioq;
+ eventq->ioq = NULL;
+
+ spin_unlock_irqrestore(&eventq->lock, flags);
+
+ if (ioq)
+ ioq_put(ioq);
+}
+
+static int
+kvm_vbus_alloc(struct kvm_vcpu *vcpu)
+{
+ struct vbus *vbus = task_vbus_get(current);
+ struct vbus_client *client;
+ struct kvm_vbus *kvbus;
+ int i;
+
+ if (!vbus)
+ return -EPERM;
+
+ client = vbus_client_attach(vbus);
+ if (!client) {
+ vbus_put(vbus);
+ return -ENOMEM;
+ }
+
+ kvbus = kzalloc(sizeof(*kvbus), GFP_KERNEL);
+ if (!kvbus) {
+ vbus_put(vbus);
+ vbus_client_put(client);
+ return -ENOMEM;
+ }
+
+ kvbus->irqsrc = kvm_request_irq_source_id(vcpu->kvm);
+ if (kvbus->irqsrc < 0) {
+ vbus_put(vbus);
+ vbus_client_put(client);
+ return kvbus->irqsrc;
+ }
+
+ atomic_set(&kvbus->refs, 1);
+ init_completion(&kvbus->free); /* signaled when all refs drop */
+
+ mutex_init(&kvbus->lock);
+ kvbus->state = kvm_vbus_state_registration;
+ kvbus->kvm = vcpu->kvm;
+ kvbus->vbus = vbus;
+ kvbus->client = client;
+
+ for (i = 0; i < EVENTQ_COUNT; i++)
+ kvm_vbus_eventq_init(&kvbus->eventq.queues[i], i);
+
+ vcpu->kvm->kvbus = kvbus;
+
+ kvbus->ctx = kvm_memctx_alloc(vcpu->kvm);
+
+ kvbus->vbusnotify.notifier_call = vbus_notifier;
+ kvbus->vbusnotify.priority = 0;
+
+ return 0;
+}
+
+void
+kvm_vbus_release(struct kvm_vbus *kvbus)
+{
+ int i;
+
+ if (!kvbus)
+ return;
+
+ if (kvbus->ctx)
+ vbus_memctx_put(kvbus->ctx);
+
+ for (i = 0; i < EVENTQ_COUNT; i++)
+ kvm_vbus_eventq_detach(&kvbus->eventq.queues[i]);
+
+ if (kvbus->client)
+ vbus_client_put(kvbus->client);
+
+ if (kvbus->vbus) {
+ vbus_notifier_unregister(kvbus->vbus, &kvbus->vbusnotify);
+ vbus_put(kvbus->vbus);
+ }
+
+ kvm_vbus_put(kvbus);
+
+ /* block here until all outstanding references drop to zero */
+ wait_for_completion(&kvbus->free);
+
+ if (kvbus->irqsrc)
+ kvm_free_irq_source_id(kvbus->kvm, kvbus->irqsrc);
+
+ kvbus->kvm->kvbus = NULL;
+
+ kfree(kvbus);
+}
+
+/*
+ * ------------------
+ * hypercall implementation
+ * ------------------
+ */
+
+static int
+hc_busopen(struct kvm_vcpu *vcpu, void *data)
+{
+ struct kvm_vbus_busopen *args = data;
+
+ if (args->magic != KVM_VBUS_MAGIC)
+ return -EINVAL;
+
+ if (args->version != KVM_VBUS_VERSION)
+ return -EINVAL;
+
+ args->capabilities = 0;
+
+ /*
+ * A guest that resets will try to (re) open the bus, even though
+ * it may have been already opened by the previous session. We
+ * turn this into our reset notification by freeing the previous
+ * instance. This will close all of our previous device connections
+ * etc.
+ */
+ if (vcpu->kvm->kvbus)
+ kvm_vbus_release(vcpu->kvm->kvbus);
+
+ return kvm_vbus_alloc(vcpu);
+}
+
+static int
+hc_busreg(struct kvm_vcpu *vcpu, void *data)
+{
+ struct kvm_vbus_busreg *args = data;
+ struct kvm_vbus_eventqreg *qreg = &args->eventq[0];
+ struct kvm_vbus *kvbus = vcpu->kvm->kvbus;
+ int i;
+ int ret;
+
+ if (args->count != kvbus->eventq.count)
+ return -EINVAL;
+
+ for (i = 0; i < EVENTQ_COUNT; i++) {
+ ret = kvm_vbus_eventq_attach(kvbus,
+ &kvbus->eventq.queues[i],
+ qreg->count,
+ qreg->ring,
+ qreg->data);
+ if (ret < 0)
+ return ret;
+ }
+
+ ret = vbus_notifier_register(kvbus->vbus, &kvbus->vbusnotify);
+ if (ret < 0)
+ return ret;
+
+ kvbus->state = kvm_vbus_state_running;
+
+ return 0;
+}
+
+static int
+hc_deviceopen(struct kvm_vcpu *vcpu, void *data)
+{
+ struct vbus_deviceopen *args = data;
+ struct kvm_vbus *kvbus = vcpu->kvm->kvbus;
+ struct vbus_client *c = kvbus->client;
+
+ return c->ops->deviceopen(c, kvbus->ctx,
+ args->devid, args->version, &args->handle);
+}
+
+static int
+hc_deviceclose(struct kvm_vcpu *vcpu, void *data)
+{
+ __u64 devh = *(__u64 *)data;
+ struct vbus_client *c = to_client(vcpu);
+
+ return c->ops->deviceclose(c, devh);
+}
+
+static int
+hc_devicecall(struct kvm_vcpu *vcpu, void *data)
+{
+ struct vbus_devicecall *args = data;
+ struct vbus_client *c = to_client(vcpu);
+
+ return c->ops->devicecall(c, args->devh, args->func,
+ (void *)args->datap, args->len, args->flags);
+}
+
+static int
+hc_deviceshm(struct kvm_vcpu *vcpu, void *data)
+{
+ struct vbus_deviceshm *args = data;
+ struct kvm_vbus *kvbus = vcpu->kvm->kvbus;
+ struct vbus_client *c = to_client(vcpu);
+ struct device_signal *_signal = NULL;
+ struct shm_signal *signal = NULL;
+ struct kvm_shm *_shm;
+ u64 handle;
+ int ret;
+
+ ret = kvm_shm_map(kvbus, args->datap, args->len, &_shm);
+ if (ret < 0)
+ return ret;
+
+ /*
+ * Establishing a signal is optional
+ */
+ if (args->signal.offset != -1) {
+ ret = device_signal_alloc(kvbus, &_shm->shm,
+ args->signal.offset,
+ args->signal.prio,
+ args->signal.cookie,
+ &_signal);
+ if (ret < 0)
+ goto out;
+
+ signal = &_signal->signal;
+ }
+
+ ret = c->ops->deviceshm(c, args->devh, args->id,
+ &_shm->shm, signal,
+ args->flags, &handle);
+ if (ret < 0)
+ goto out;
+
+ args->handle = handle;
+ if (_signal)
+ _signal->handle = handle;
+
+ return 0;
+
+out:
+ if (signal)
+ shm_signal_put(signal);
+
+ vbus_shm_put(&_shm->shm);
+ return ret;
+}
+
+static int
+hc_shmsignal(struct kvm_vcpu *vcpu, void *data)
+{
+ __u64 handle = *(__u64 *)data;
+ struct kvm_vbus *kvbus;
+ struct vbus_client *c = to_client(vcpu);
+
+ /* A handle not 0-7 is targeted at a device's shm */
+ if (handle > EVENTQ_COUNT)
+ return c->ops->shmsignal(c, handle);
+
+ kvbus = vcpu->kvm->kvbus;
+
+ /* Otherwise they are signaling one of our eventqs */
+ _shm_signal_wakeup(kvbus->eventq.queues[handle].ioq->signal);
+
+ return 0;
+}
+
+struct hc_op {
+ int nr;
+ int len;
+ int dirty;
+ int (*func)(struct kvm_vcpu *vcpu, void *args);
+};
+
+static struct hc_op _hc_busopen = {
+ .nr = KVM_VBUS_OP_BUSOPEN,
+ .len = sizeof(struct kvm_vbus_busopen),
+ .dirty = 1,
+ .func = &hc_busopen,
+};
+
+static struct hc_op _hc_busreg = {
+ .nr = KVM_VBUS_OP_BUSREG,
+ .len = sizeof(struct kvm_vbus_busreg),
+ .func = &hc_busreg,
+};
+
+static struct hc_op _hc_devopen = {
+ .nr = KVM_VBUS_OP_DEVOPEN,
+ .len = sizeof(struct vbus_deviceopen),
+ .dirty = 1,
+ .func = &hc_deviceopen,
+};
+
+static struct hc_op _hc_devclose = {
+ .nr = KVM_VBUS_OP_DEVCLOSE,
+ .len = sizeof(u64),
+ .func = &hc_deviceclose,
+};
+
+static struct hc_op _hc_devcall = {
+ .nr = KVM_VBUS_OP_DEVCALL,
+ .len = sizeof(struct vbus_devicecall),
+ .func = &hc_devicecall,
+};
+
+static struct hc_op _hc_devshm = {
+ .nr = KVM_VBUS_OP_DEVSHM,
+ .len = sizeof(struct vbus_deviceshm),
+ .dirty = 1,
+ .func = &hc_deviceshm,
+};
+
+static struct hc_op _hc_shmsignal = {
+ .nr = KVM_VBUS_OP_SHMSIGNAL,
+ .len = sizeof(u64),
+ .func = &hc_shmsignal,
+};
+
+static struct hc_op *hc_ops[] = {
+ &_hc_busopen,
+ &_hc_busreg,
+ &_hc_devopen,
+ &_hc_devclose,
+ &_hc_devcall,
+ &_hc_devshm,
+ &_hc_shmsignal,
+ NULL,
+};
+
+static int
+hc_execute_indirect(struct kvm_vcpu *vcpu, struct hc_op *op, gpa_t gpa)
+{
+ struct kvm *kvm = vcpu->kvm;
+ char *args = NULL;
+ int ret;
+
+ BUG_ON(!op->len);
+
+ args = kmalloc(op->len, GFP_KERNEL);
+ if (!args)
+ return -ENOMEM;
+
+ ret = kvm_read_guest(kvm, gpa, args, op->len);
+ if (ret < 0)
+ goto out;
+
+ ret = op->func(vcpu, args);
+
+ if (ret >= 0 && op->dirty)
+ ret = kvm_write_guest(kvm, gpa, args, op->len);
+
+out:
+ kfree(args);
+
+ return ret;
+}
+
+static int
+hc_execute_direct(struct kvm_vcpu *vcpu, struct hc_op *op, gpa_t gpa)
+{
+ struct kvm *kvm = vcpu->kvm;
+ void *args;
+ char *kaddr;
+ struct page *page;
+ int ret;
+
+ page = gfn_to_page(kvm, gpa >> PAGE_SHIFT);
+ if (page == bad_page) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ kaddr = kmap(page);
+ if (!kaddr) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ args = kaddr + offset_in_page(gpa);
+
+ ret = op->func(vcpu, args);
+
+out:
+ if (kaddr)
+ kunmap(kaddr);
+
+ if (ret >= 0 && op->dirty)
+ kvm_release_page_dirty(page);
+ else
+ kvm_release_page_clean(page);
+
+ return ret;
+}
+
+static int
+hc_execute(struct kvm_vcpu *vcpu, struct hc_op *op, gpa_t gpa, size_t len)
+{
+ if (len != op->len)
+ return -EINVAL;
+
+ /*
+ * Execute-immediate if there is no data
+ */
+ if (!len)
+ return op->func(vcpu, NULL);
+
+ /*
+ * We will need to copy the arguments in the unlikely case that the
+ * gpa pointer crosses a page boundary
+ *
+ * FIXME: Is it safe to assume PAGE_SIZE is relevant to gpa?
+ */
+ if (unlikely(len && (offset_in_page(gpa) + len) > PAGE_SIZE))
+ return hc_execute_indirect(vcpu, op, gpa);
+
+ /*
+ * Otherwise just execute with zero-copy by mapping the arguments
+ */
+ return hc_execute_direct(vcpu, op, gpa);
+}
+
+/*
+ * Our hypercall format will always follow with the call-id in arg[0],
+ * a pointer to the arguments in arg[1], and the argument length in arg[2]
+ */
+int
+kvm_vbus_hc(struct kvm_vcpu *vcpu, int nr, gpa_t gpa, size_t len)
+{
+ struct kvm_vbus *kvbus = vcpu->kvm->kvbus;
+ enum kvm_vbus_state state = kvbus ? kvbus->state : kvm_vbus_state_init;
+ int i;
+
+ PDEBUG("nr=%d, state=%d\n", nr, state);
+
+ switch (state) {
+ case kvm_vbus_state_init:
+ if (nr != KVM_VBUS_OP_BUSOPEN) {
+ PDEBUG("expected BUSOPEN\n");
+ return -EINVAL;
+ }
+ break;
+ case kvm_vbus_state_registration:
+ if (nr != KVM_VBUS_OP_BUSREG) {
+ PDEBUG("expected BUSREG\n");
+ return -EINVAL;
+ }
+ break;
+ default:
+ break;
+ }
+
+ for (i = 0; i < ARRAY_SIZE(hc_ops); i++) {
+ struct hc_op *op = hc_ops[i];
+
+ if (op->nr != nr)
+ continue;
+
+ return hc_execute(vcpu, op, gpa, len);
+ }
+
+ PDEBUG("error: no matching function for nr=%d\n", nr);
+
+ return -EINVAL;
+}
+
+int kvm_vbus_assign_gsi(struct kvm *kvm, int queue, int gsi)
+{
+ struct kvm_vbus *kvbus = kvm->kvbus;
+
+ if (!kvbus
+ || queue != kvbus->eventq.count
+ || queue >= ARRAY_SIZE(kvbus->eventq.queues))
+ return -EINVAL;
+
+ kvbus->eventq.queues[queue].gsi = gsi;
+ kvbus->eventq.count++;
+
+ return 0;
+}