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Subject[PATCH v6 15/18] virt: acrn: Introduce ioeventfd
Date
From: Shuo Liu <shuo.a.liu@intel.com>

ioeventfd is a mechanism to register PIO/MMIO regions to trigger an
eventfd signal when written to by a User VM. ACRN userspace can register
any arbitrary I/O address with a corresponding eventfd and then pass the
eventfd to a specific end-point of interest for handling.

Vhost is a kernel-level virtio server which uses eventfd for signalling.
To support vhost on ACRN, ioeventfd is introduced in HSM.

A new I/O client dedicated to ioeventfd is associated with a User VM
during VM creation. HSM provides ioctls to associate an I/O region with
a eventfd. The I/O client signals a eventfd once its corresponding I/O
region is matched with an I/O request.

Signed-off-by: Shuo Liu <shuo.a.liu@intel.com>
Reviewed-by: Zhi Wang <zhi.a.wang@intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Cc: Zhi Wang <zhi.a.wang@intel.com>
Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Cc: Yu Wang <yu1.wang@intel.com>
Cc: Reinette Chatre <reinette.chatre@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/virt/acrn/Kconfig | 1 +
drivers/virt/acrn/Makefile | 2 +-
drivers/virt/acrn/acrn_drv.h | 10 ++
drivers/virt/acrn/hsm.c | 8 +
drivers/virt/acrn/ioeventfd.c | 273 ++++++++++++++++++++++++++++++++++
drivers/virt/acrn/vm.c | 2 +
include/uapi/linux/acrn.h | 29 ++++
7 files changed, 324 insertions(+), 1 deletion(-)
create mode 100644 drivers/virt/acrn/ioeventfd.c

diff --git a/drivers/virt/acrn/Kconfig b/drivers/virt/acrn/Kconfig
index 36c80378c30c..3e1a61c9d8d8 100644
--- a/drivers/virt/acrn/Kconfig
+++ b/drivers/virt/acrn/Kconfig
@@ -2,6 +2,7 @@
config ACRN_HSM
tristate "ACRN Hypervisor Service Module"
depends on ACRN_GUEST
+ select EVENTFD
help
ACRN Hypervisor Service Module (HSM) is a kernel module which
communicates with ACRN userspace through ioctls and talks to
diff --git a/drivers/virt/acrn/Makefile b/drivers/virt/acrn/Makefile
index 21721cbf6a80..755b583b32ca 100644
--- a/drivers/virt/acrn/Makefile
+++ b/drivers/virt/acrn/Makefile
@@ -1,3 +1,3 @@
# SPDX-License-Identifier: GPL-2.0
obj-$(CONFIG_ACRN_HSM) := acrn.o
-acrn-y := hsm.o vm.o mm.o ioreq.o
+acrn-y := hsm.o vm.o mm.o ioreq.o ioeventfd.o
diff --git a/drivers/virt/acrn/acrn_drv.h b/drivers/virt/acrn/acrn_drv.h
index 862d195d4774..74c609cf60ae 100644
--- a/drivers/virt/acrn/acrn_drv.h
+++ b/drivers/virt/acrn/acrn_drv.h
@@ -156,6 +156,9 @@ extern rwlock_t acrn_vm_list_lock;
* @ioreq_page: The page of the I/O request shared buffer
* @pci_conf_addr: Address of a PCI configuration access emulation
* @monitor_page: Page of interrupt statistics of User VM
+ * @ioeventfds_lock: Lock to protect ioeventfds list
+ * @ioeventfds: List to link all hsm_ioeventfd
+ * @ioeventfd_client: I/O client for ioeventfds of the VM
*/
struct acrn_vm {
struct list_head list;
@@ -172,6 +175,9 @@ struct acrn_vm {
struct page *ioreq_page;
u32 pci_conf_addr;
struct page *monitor_page;
+ struct mutex ioeventfds_lock;
+ struct list_head ioeventfds;
+ struct acrn_ioreq_client *ioeventfd_client;
};

struct acrn_vm *acrn_vm_create(struct acrn_vm *vm,
@@ -204,4 +210,8 @@ void acrn_ioreq_range_del(struct acrn_ioreq_client *client,

int acrn_msi_inject(struct acrn_vm *vm, u64 msi_addr, u64 msi_data);

+int acrn_ioeventfd_init(struct acrn_vm *vm);
+int acrn_ioeventfd_config(struct acrn_vm *vm, struct acrn_ioeventfd *args);
+void acrn_ioeventfd_deinit(struct acrn_vm *vm);
+
#endif /* __ACRN_HSM_DRV_H */
diff --git a/drivers/virt/acrn/hsm.c b/drivers/virt/acrn/hsm.c
index 700006e2465b..e0d48a512017 100644
--- a/drivers/virt/acrn/hsm.c
+++ b/drivers/virt/acrn/hsm.c
@@ -111,6 +111,7 @@ static long acrn_dev_ioctl(struct file *filp, unsigned int cmd,
struct acrn_vcpu_regs *cpu_regs;
struct acrn_ioreq_notify notify;
struct acrn_ptdev_irq *irq_info;
+ struct acrn_ioeventfd ioeventfd;
struct acrn_vm_memmap memmap;
struct acrn_msi_entry *msi;
struct acrn_pcidev *pcidev;
@@ -315,6 +316,13 @@ static long acrn_dev_ioctl(struct file *filp, unsigned int cmd,

ret = pmcmd_ioctl(cstate_cmd, (void __user *)ioctl_param);
break;
+ case ACRN_IOCTL_IOEVENTFD:
+ if (copy_from_user(&ioeventfd, (void __user *)ioctl_param,
+ sizeof(ioeventfd)))
+ return -EFAULT;
+
+ ret = acrn_ioeventfd_config(vm, &ioeventfd);
+ break;
default:
dev_dbg(acrn_dev.this_device, "Unknown IOCTL 0x%x!\n", cmd);
ret = -ENOTTY;
diff --git a/drivers/virt/acrn/ioeventfd.c b/drivers/virt/acrn/ioeventfd.c
new file mode 100644
index 000000000000..ac4037e9f947
--- /dev/null
+++ b/drivers/virt/acrn/ioeventfd.c
@@ -0,0 +1,273 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ACRN HSM eventfd - use eventfd objects to signal expected I/O requests
+ *
+ * Copyright (C) 2020 Intel Corporation. All rights reserved.
+ *
+ * Authors:
+ * Shuo Liu <shuo.a.liu@intel.com>
+ * Yakui Zhao <yakui.zhao@intel.com>
+ */
+
+#include <linux/eventfd.h>
+#include <linux/slab.h>
+
+#include "acrn_drv.h"
+
+/**
+ * struct hsm_ioeventfd - Properties of HSM ioeventfd
+ * @list: Entry within &acrn_vm.ioeventfds of ioeventfds of a VM
+ * @eventfd: Eventfd of the HSM ioeventfd
+ * @addr: Address of I/O range
+ * @data: Data for matching
+ * @length: Length of I/O range
+ * @type: Type of I/O range (ACRN_IOREQ_TYPE_MMIO/ACRN_IOREQ_TYPE_PORTIO)
+ * @wildcard: Data matching or not
+ */
+struct hsm_ioeventfd {
+ struct list_head list;
+ struct eventfd_ctx *eventfd;
+ u64 addr;
+ u64 data;
+ int length;
+ int type;
+ bool wildcard;
+};
+
+static inline int ioreq_type_from_flags(int flags)
+{
+ return flags & ACRN_IOEVENTFD_FLAG_PIO ?
+ ACRN_IOREQ_TYPE_PORTIO : ACRN_IOREQ_TYPE_MMIO;
+}
+
+static void acrn_ioeventfd_shutdown(struct acrn_vm *vm, struct hsm_ioeventfd *p)
+{
+ lockdep_assert_held(&vm->ioeventfds_lock);
+
+ eventfd_ctx_put(p->eventfd);
+ list_del(&p->list);
+ kfree(p);
+}
+
+static bool hsm_ioeventfd_is_conflict(struct acrn_vm *vm,
+ struct hsm_ioeventfd *ioeventfd)
+{
+ struct hsm_ioeventfd *p;
+
+ lockdep_assert_held(&vm->ioeventfds_lock);
+
+ /* Either one is wildcard, the data matching will be skipped. */
+ list_for_each_entry(p, &vm->ioeventfds, list)
+ if (p->eventfd == ioeventfd->eventfd &&
+ p->addr == ioeventfd->addr &&
+ p->type == ioeventfd->type &&
+ (p->wildcard || ioeventfd->wildcard ||
+ p->data == ioeventfd->data))
+ return true;
+
+ return false;
+}
+
+/*
+ * Assign an eventfd to a VM and create a HSM ioeventfd associated with the
+ * eventfd. The properties of the HSM ioeventfd are built from a &struct
+ * acrn_ioeventfd.
+ */
+static int acrn_ioeventfd_assign(struct acrn_vm *vm,
+ struct acrn_ioeventfd *args)
+{
+ struct eventfd_ctx *eventfd;
+ struct hsm_ioeventfd *p;
+ int ret;
+
+ /* Check for range overflow */
+ if (args->addr + args->len < args->addr)
+ return -EINVAL;
+
+ /*
+ * Currently, acrn_ioeventfd is used to support vhost. 1,2,4,8 width
+ * accesses can cover vhost's requirements.
+ */
+ if (!(args->len == 1 || args->len == 2 ||
+ args->len == 4 || args->len == 8))
+ return -EINVAL;
+
+ eventfd = eventfd_ctx_fdget(args->fd);
+ if (IS_ERR(eventfd))
+ return PTR_ERR(eventfd);
+
+ p = kzalloc(sizeof(*p), GFP_KERNEL);
+ if (!p) {
+ ret = -ENOMEM;
+ goto fail;
+ }
+
+ INIT_LIST_HEAD(&p->list);
+ p->addr = args->addr;
+ p->length = args->len;
+ p->eventfd = eventfd;
+ p->type = ioreq_type_from_flags(args->flags);
+
+ /*
+ * ACRN_IOEVENTFD_FLAG_DATAMATCH flag is set in virtio 1.0 support, the
+ * writing of notification register of each virtqueue may trigger the
+ * notification. There is no data matching requirement.
+ */
+ if (args->flags & ACRN_IOEVENTFD_FLAG_DATAMATCH)
+ p->data = args->data;
+ else
+ p->wildcard = true;
+
+ mutex_lock(&vm->ioeventfds_lock);
+
+ if (hsm_ioeventfd_is_conflict(vm, p)) {
+ ret = -EEXIST;
+ goto unlock_fail;
+ }
+
+ /* register the I/O range into ioreq client */
+ ret = acrn_ioreq_range_add(vm->ioeventfd_client, p->type,
+ p->addr, p->addr + p->length - 1);
+ if (ret < 0)
+ goto unlock_fail;
+
+ list_add_tail(&p->list, &vm->ioeventfds);
+ mutex_unlock(&vm->ioeventfds_lock);
+
+ return 0;
+
+unlock_fail:
+ mutex_unlock(&vm->ioeventfds_lock);
+ kfree(p);
+fail:
+ eventfd_ctx_put(eventfd);
+ return ret;
+}
+
+static int acrn_ioeventfd_deassign(struct acrn_vm *vm,
+ struct acrn_ioeventfd *args)
+{
+ struct hsm_ioeventfd *p;
+ struct eventfd_ctx *eventfd;
+
+ eventfd = eventfd_ctx_fdget(args->fd);
+ if (IS_ERR(eventfd))
+ return PTR_ERR(eventfd);
+
+ mutex_lock(&vm->ioeventfds_lock);
+ list_for_each_entry(p, &vm->ioeventfds, list) {
+ if (p->eventfd != eventfd)
+ continue;
+
+ acrn_ioreq_range_del(vm->ioeventfd_client, p->type,
+ p->addr, p->addr + p->length - 1);
+ acrn_ioeventfd_shutdown(vm, p);
+ break;
+ }
+ mutex_unlock(&vm->ioeventfds_lock);
+
+ eventfd_ctx_put(eventfd);
+ return 0;
+}
+
+static struct hsm_ioeventfd *hsm_ioeventfd_match(struct acrn_vm *vm, u64 addr,
+ u64 data, int len, int type)
+{
+ struct hsm_ioeventfd *p = NULL;
+
+ lockdep_assert_held(&vm->ioeventfds_lock);
+
+ list_for_each_entry(p, &vm->ioeventfds, list) {
+ if (p->type == type && p->addr == addr && p->length >= len &&
+ (p->wildcard || p->data == data))
+ return p;
+ }
+
+ return NULL;
+}
+
+static int acrn_ioeventfd_handler(struct acrn_ioreq_client *client,
+ struct acrn_io_request *req)
+{
+ struct hsm_ioeventfd *p;
+ u64 addr, val;
+ int size;
+
+ if (req->type == ACRN_IOREQ_TYPE_MMIO) {
+ /*
+ * I/O requests are dispatched by range check only, so a
+ * acrn_ioreq_client need process both READ and WRITE accesses
+ * of same range. READ accesses are safe to be ignored here
+ * because virtio PCI devices write the notify registers for
+ * notification.
+ */
+ if (req->reqs.mmio_request.direction == ACRN_IOREQ_DIR_READ) {
+ /* reading does nothing and return 0 */
+ req->reqs.mmio_request.value = 0;
+ return 0;
+ }
+ addr = req->reqs.mmio_request.address;
+ size = req->reqs.mmio_request.size;
+ val = req->reqs.mmio_request.value;
+ } else {
+ if (req->reqs.pio_request.direction == ACRN_IOREQ_DIR_READ) {
+ /* reading does nothing and return 0 */
+ req->reqs.pio_request.value = 0;
+ return 0;
+ }
+ addr = req->reqs.pio_request.address;
+ size = req->reqs.pio_request.size;
+ val = req->reqs.pio_request.value;
+ }
+
+ mutex_lock(&client->vm->ioeventfds_lock);
+ p = hsm_ioeventfd_match(client->vm, addr, val, size, req->type);
+ if (p)
+ eventfd_signal(p->eventfd, 1);
+ mutex_unlock(&client->vm->ioeventfds_lock);
+
+ return 0;
+}
+
+int acrn_ioeventfd_config(struct acrn_vm *vm, struct acrn_ioeventfd *args)
+{
+ int ret;
+
+ if (args->flags & ACRN_IOEVENTFD_FLAG_DEASSIGN)
+ ret = acrn_ioeventfd_deassign(vm, args);
+ else
+ ret = acrn_ioeventfd_assign(vm, args);
+
+ return ret;
+}
+
+int acrn_ioeventfd_init(struct acrn_vm *vm)
+{
+ char name[ACRN_NAME_LEN];
+
+ mutex_init(&vm->ioeventfds_lock);
+ INIT_LIST_HEAD(&vm->ioeventfds);
+ snprintf(name, sizeof(name), "ioeventfd-%u", vm->vmid);
+ vm->ioeventfd_client = acrn_ioreq_client_create(vm,
+ acrn_ioeventfd_handler,
+ NULL, false, name);
+ if (!vm->ioeventfd_client) {
+ dev_err(acrn_dev.this_device, "Failed to create ioeventfd ioreq client!\n");
+ return -EINVAL;
+ }
+
+ dev_dbg(acrn_dev.this_device, "VM %u ioeventfd init.\n", vm->vmid);
+ return 0;
+}
+
+void acrn_ioeventfd_deinit(struct acrn_vm *vm)
+{
+ struct hsm_ioeventfd *p, *next;
+
+ dev_dbg(acrn_dev.this_device, "VM %u ioeventfd deinit.\n", vm->vmid);
+ acrn_ioreq_client_destroy(vm->ioeventfd_client);
+ mutex_lock(&vm->ioeventfds_lock);
+ list_for_each_entry_safe(p, next, &vm->ioeventfds, list)
+ acrn_ioeventfd_shutdown(vm, p);
+ mutex_unlock(&vm->ioeventfds_lock);
+}
diff --git a/drivers/virt/acrn/vm.c b/drivers/virt/acrn/vm.c
index 38304aeef181..3c671b03b273 100644
--- a/drivers/virt/acrn/vm.c
+++ b/drivers/virt/acrn/vm.c
@@ -50,6 +50,7 @@ struct acrn_vm *acrn_vm_create(struct acrn_vm *vm,
list_add(&vm->list, &acrn_vm_list);
write_unlock_bh(&acrn_vm_list_lock);

+ acrn_ioeventfd_init(vm);
dev_dbg(acrn_dev.this_device, "VM %u created.\n", vm->vmid);
return vm;
}
@@ -67,6 +68,7 @@ int acrn_vm_destroy(struct acrn_vm *vm)
list_del_init(&vm->list);
write_unlock_bh(&acrn_vm_list_lock);

+ acrn_ioeventfd_deinit(vm);
acrn_ioreq_deinit(vm);
if (vm->monitor_page) {
put_page(vm->monitor_page);
diff --git a/include/uapi/linux/acrn.h b/include/uapi/linux/acrn.h
index cb584f61056b..d6d026f7454a 100644
--- a/include/uapi/linux/acrn.h
+++ b/include/uapi/linux/acrn.h
@@ -378,6 +378,32 @@ enum acrn_pm_cmd_type {
ACRN_PMCMD_GET_CX_DATA,
};

+#define ACRN_IOEVENTFD_FLAG_PIO 0x01
+#define ACRN_IOEVENTFD_FLAG_DATAMATCH 0x02
+#define ACRN_IOEVENTFD_FLAG_DEASSIGN 0x04
+/**
+ * struct acrn_ioeventfd - Data to operate a &struct hsm_ioeventfd
+ * @fd: The fd of eventfd associated with a hsm_ioeventfd
+ * @flags: Logical-OR of ACRN_IOEVENTFD_FLAG_*
+ * @addr: The start address of IO range of ioeventfd
+ * @len: The length of IO range of ioeventfd
+ * @reserved: Reserved
+ * @data: Data for data matching
+ *
+ * Without flag ACRN_IOEVENTFD_FLAG_DEASSIGN, ioctl ACRN_IOCTL_IOEVENTFD
+ * creates a &struct hsm_ioeventfd with properties originated from &struct
+ * acrn_ioeventfd. With flag ACRN_IOEVENTFD_FLAG_DEASSIGN, ioctl
+ * ACRN_IOCTL_IOEVENTFD destroys the &struct hsm_ioeventfd matching the fd.
+ */
+struct acrn_ioeventfd {
+ __u32 fd;
+ __u32 flags;
+ __u64 addr;
+ __u32 len;
+ __u32 reserved;
+ __u64 data;
+};
+
/* The ioctl type, documented in ioctl-number.rst */
#define ACRN_IOCTL_TYPE 0xA2

@@ -432,4 +458,7 @@ enum acrn_pm_cmd_type {
#define ACRN_IOCTL_PM_GET_CPU_STATE \
_IOWR(ACRN_IOCTL_TYPE, 0x60, __u64)

+#define ACRN_IOCTL_IOEVENTFD \
+ _IOW(ACRN_IOCTL_TYPE, 0x70, struct acrn_ioeventfd)
+
#endif /* _UAPI_ACRN_H */
--
2.28.0
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