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Subject[PATCH v6 16/18] virt: acrn: Introduce irqfd
Date
From: Shuo Liu <shuo.a.liu@intel.com>

irqfd is a mechanism to inject a specific interrupt to a User VM using a
decoupled eventfd mechanism.

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

HSM provides ioctls to associate a virtual Message Signaled Interrupt
(MSI) with an eventfd. The corresponding virtual MSI will be injected
into a User VM once the eventfd got signal.

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/Makefile | 2 +-
drivers/virt/acrn/acrn_drv.h | 10 ++
drivers/virt/acrn/hsm.c | 7 ++
drivers/virt/acrn/irqfd.c | 235 +++++++++++++++++++++++++++++++++++
drivers/virt/acrn/vm.c | 3 +
include/uapi/linux/acrn.h | 15 +++
6 files changed, 271 insertions(+), 1 deletion(-)
create mode 100644 drivers/virt/acrn/irqfd.c

diff --git a/drivers/virt/acrn/Makefile b/drivers/virt/acrn/Makefile
index 755b583b32ca..08ce641dcfa1 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 ioeventfd.o
+acrn-y := hsm.o vm.o mm.o ioreq.o ioeventfd.o irqfd.o
diff --git a/drivers/virt/acrn/acrn_drv.h b/drivers/virt/acrn/acrn_drv.h
index 74c609cf60ae..be4b5b90277c 100644
--- a/drivers/virt/acrn/acrn_drv.h
+++ b/drivers/virt/acrn/acrn_drv.h
@@ -159,6 +159,9 @@ extern rwlock_t acrn_vm_list_lock;
* @ioeventfds_lock: Lock to protect ioeventfds list
* @ioeventfds: List to link all hsm_ioeventfd
* @ioeventfd_client: I/O client for ioeventfds of the VM
+ * @irqfds_lock: Lock to protect irqfds list
+ * @irqfds: List to link all hsm_irqfd
+ * @irqfd_wq: Workqueue for irqfd async shutdown
*/
struct acrn_vm {
struct list_head list;
@@ -178,6 +181,9 @@ struct acrn_vm {
struct mutex ioeventfds_lock;
struct list_head ioeventfds;
struct acrn_ioreq_client *ioeventfd_client;
+ struct mutex irqfds_lock;
+ struct list_head irqfds;
+ struct workqueue_struct *irqfd_wq;
};

struct acrn_vm *acrn_vm_create(struct acrn_vm *vm,
@@ -214,4 +220,8 @@ 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);

+int acrn_irqfd_init(struct acrn_vm *vm);
+int acrn_irqfd_config(struct acrn_vm *vm, struct acrn_irqfd *args);
+void acrn_irqfd_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 e0d48a512017..b8c1255247e5 100644
--- a/drivers/virt/acrn/hsm.c
+++ b/drivers/virt/acrn/hsm.c
@@ -115,6 +115,7 @@ static long acrn_dev_ioctl(struct file *filp, unsigned int cmd,
struct acrn_vm_memmap memmap;
struct acrn_msi_entry *msi;
struct acrn_pcidev *pcidev;
+ struct acrn_irqfd irqfd;
struct page *page;
u64 cstate_cmd;
int ret = 0;
@@ -323,6 +324,12 @@ static long acrn_dev_ioctl(struct file *filp, unsigned int cmd,

ret = acrn_ioeventfd_config(vm, &ioeventfd);
break;
+ case ACRN_IOCTL_IRQFD:
+ if (copy_from_user(&irqfd, (void __user *)ioctl_param,
+ sizeof(irqfd)))
+ return -EFAULT;
+ ret = acrn_irqfd_config(vm, &irqfd);
+ break;
default:
dev_dbg(acrn_dev.this_device, "Unknown IOCTL 0x%x!\n", cmd);
ret = -ENOTTY;
diff --git a/drivers/virt/acrn/irqfd.c b/drivers/virt/acrn/irqfd.c
new file mode 100644
index 000000000000..a8766d528e29
--- /dev/null
+++ b/drivers/virt/acrn/irqfd.c
@@ -0,0 +1,235 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ACRN HSM irqfd: use eventfd objects to inject virtual interrupts
+ *
+ * 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/file.h>
+#include <linux/poll.h>
+#include <linux/slab.h>
+
+#include "acrn_drv.h"
+
+static LIST_HEAD(acrn_irqfd_clients);
+static DEFINE_MUTEX(acrn_irqfds_mutex);
+
+/**
+ * struct hsm_irqfd - Properties of HSM irqfd
+ * @vm: Associated VM pointer
+ * @wait: Entry of wait-queue
+ * @shutdown: Async shutdown work
+ * @eventfd: Associated eventfd
+ * @list: Entry within &acrn_vm.irqfds of irqfds of a VM
+ * @pt: Structure for select/poll on the associated eventfd
+ * @msi: MSI data
+ */
+struct hsm_irqfd {
+ struct acrn_vm *vm;
+ wait_queue_entry_t wait;
+ struct work_struct shutdown;
+ struct eventfd_ctx *eventfd;
+ struct list_head list;
+ poll_table pt;
+ struct acrn_msi_entry msi;
+};
+
+static void acrn_irqfd_inject(struct hsm_irqfd *irqfd)
+{
+ struct acrn_vm *vm = irqfd->vm;
+
+ acrn_msi_inject(vm, irqfd->msi.msi_addr,
+ irqfd->msi.msi_data);
+}
+
+static void hsm_irqfd_shutdown(struct hsm_irqfd *irqfd)
+{
+ u64 cnt;
+
+ lockdep_assert_held(&irqfd->vm->irqfds_lock);
+
+ /* remove from wait queue */
+ list_del_init(&irqfd->list);
+ eventfd_ctx_remove_wait_queue(irqfd->eventfd, &irqfd->wait, &cnt);
+ eventfd_ctx_put(irqfd->eventfd);
+ kfree(irqfd);
+}
+
+static void hsm_irqfd_shutdown_work(struct work_struct *work)
+{
+ struct hsm_irqfd *irqfd;
+ struct acrn_vm *vm;
+
+ irqfd = container_of(work, struct hsm_irqfd, shutdown);
+ vm = irqfd->vm;
+ mutex_lock(&vm->irqfds_lock);
+ if (!list_empty(&irqfd->list))
+ hsm_irqfd_shutdown(irqfd);
+ mutex_unlock(&vm->irqfds_lock);
+}
+
+/* Called with wqh->lock held and interrupts disabled */
+static int hsm_irqfd_wakeup(wait_queue_entry_t *wait, unsigned int mode,
+ int sync, void *key)
+{
+ unsigned long poll_bits = (unsigned long)key;
+ struct hsm_irqfd *irqfd;
+ struct acrn_vm *vm;
+
+ irqfd = container_of(wait, struct hsm_irqfd, wait);
+ vm = irqfd->vm;
+ if (poll_bits & POLLIN)
+ /* An event has been signaled, inject an interrupt */
+ acrn_irqfd_inject(irqfd);
+
+ if (poll_bits & POLLHUP)
+ /* Do shutdown work in thread to hold wqh->lock */
+ queue_work(vm->irqfd_wq, &irqfd->shutdown);
+
+ return 0;
+}
+
+static void hsm_irqfd_poll_func(struct file *file, wait_queue_head_t *wqh,
+ poll_table *pt)
+{
+ struct hsm_irqfd *irqfd;
+
+ irqfd = container_of(pt, struct hsm_irqfd, pt);
+ add_wait_queue(wqh, &irqfd->wait);
+}
+
+/*
+ * Assign an eventfd to a VM and create a HSM irqfd associated with the
+ * eventfd. The properties of the HSM irqfd are built from a &struct
+ * acrn_irqfd.
+ */
+static int acrn_irqfd_assign(struct acrn_vm *vm, struct acrn_irqfd *args)
+{
+ struct eventfd_ctx *eventfd = NULL;
+ struct hsm_irqfd *irqfd, *tmp;
+ unsigned int events;
+ struct fd f;
+ int ret = 0;
+
+ irqfd = kzalloc(sizeof(*irqfd), GFP_KERNEL);
+ if (!irqfd)
+ return -ENOMEM;
+
+ irqfd->vm = vm;
+ memcpy(&irqfd->msi, &args->msi, sizeof(args->msi));
+ INIT_LIST_HEAD(&irqfd->list);
+ INIT_WORK(&irqfd->shutdown, hsm_irqfd_shutdown_work);
+
+ f = fdget(args->fd);
+ if (!f.file) {
+ ret = -EBADF;
+ goto out;
+ }
+
+ eventfd = eventfd_ctx_fileget(f.file);
+ if (IS_ERR(eventfd)) {
+ ret = PTR_ERR(eventfd);
+ goto fail;
+ }
+
+ irqfd->eventfd = eventfd;
+
+ /*
+ * Install custom wake-up handling to be notified whenever underlying
+ * eventfd is signaled.
+ */
+ init_waitqueue_func_entry(&irqfd->wait, hsm_irqfd_wakeup);
+ init_poll_funcptr(&irqfd->pt, hsm_irqfd_poll_func);
+
+ mutex_lock(&vm->irqfds_lock);
+ list_for_each_entry(tmp, &vm->irqfds, list) {
+ if (irqfd->eventfd != tmp->eventfd)
+ continue;
+ ret = -EBUSY;
+ mutex_unlock(&vm->irqfds_lock);
+ goto fail;
+ }
+ list_add_tail(&irqfd->list, &vm->irqfds);
+ mutex_unlock(&vm->irqfds_lock);
+
+ /* Check the pending event in this stage */
+ events = f.file->f_op->poll(f.file, &irqfd->pt);
+
+ if (events & POLLIN)
+ acrn_irqfd_inject(irqfd);
+
+ fdput(f);
+ return 0;
+fail:
+ if (eventfd && !IS_ERR(eventfd))
+ eventfd_ctx_put(eventfd);
+
+ fdput(f);
+out:
+ kfree(irqfd);
+ return ret;
+}
+
+static int acrn_irqfd_deassign(struct acrn_vm *vm,
+ struct acrn_irqfd *args)
+{
+ struct hsm_irqfd *irqfd, *tmp;
+ struct eventfd_ctx *eventfd;
+
+ eventfd = eventfd_ctx_fdget(args->fd);
+ if (IS_ERR(eventfd))
+ return PTR_ERR(eventfd);
+
+ mutex_lock(&vm->irqfds_lock);
+ list_for_each_entry_safe(irqfd, tmp, &vm->irqfds, list) {
+ if (irqfd->eventfd == eventfd) {
+ hsm_irqfd_shutdown(irqfd);
+ break;
+ }
+ }
+ mutex_unlock(&vm->irqfds_lock);
+ eventfd_ctx_put(eventfd);
+
+ return 0;
+}
+
+int acrn_irqfd_config(struct acrn_vm *vm, struct acrn_irqfd *args)
+{
+ int ret;
+
+ if (args->flags & ACRN_IRQFD_FLAG_DEASSIGN)
+ ret = acrn_irqfd_deassign(vm, args);
+ else
+ ret = acrn_irqfd_assign(vm, args);
+
+ return ret;
+}
+
+int acrn_irqfd_init(struct acrn_vm *vm)
+{
+ INIT_LIST_HEAD(&vm->irqfds);
+ mutex_init(&vm->irqfds_lock);
+ vm->irqfd_wq = alloc_workqueue("acrn_irqfd-%u", 0, 0, vm->vmid);
+ if (!vm->irqfd_wq)
+ return -ENOMEM;
+
+ dev_dbg(acrn_dev.this_device, "VM %u irqfd init.\n", vm->vmid);
+ return 0;
+}
+
+void acrn_irqfd_deinit(struct acrn_vm *vm)
+{
+ struct hsm_irqfd *irqfd, *next;
+
+ dev_dbg(acrn_dev.this_device, "VM %u irqfd deinit.\n", vm->vmid);
+ destroy_workqueue(vm->irqfd_wq);
+ mutex_lock(&vm->irqfds_lock);
+ list_for_each_entry_safe(irqfd, next, &vm->irqfds, list)
+ hsm_irqfd_shutdown(irqfd);
+ mutex_unlock(&vm->irqfds_lock);
+}
diff --git a/drivers/virt/acrn/vm.c b/drivers/virt/acrn/vm.c
index 3c671b03b273..7f152a74b591 100644
--- a/drivers/virt/acrn/vm.c
+++ b/drivers/virt/acrn/vm.c
@@ -51,6 +51,7 @@ struct acrn_vm *acrn_vm_create(struct acrn_vm *vm,
write_unlock_bh(&acrn_vm_list_lock);

acrn_ioeventfd_init(vm);
+ acrn_irqfd_init(vm);
dev_dbg(acrn_dev.this_device, "VM %u created.\n", vm->vmid);
return vm;
}
@@ -69,7 +70,9 @@ int acrn_vm_destroy(struct acrn_vm *vm)
write_unlock_bh(&acrn_vm_list_lock);

acrn_ioeventfd_deinit(vm);
+ acrn_irqfd_deinit(vm);
acrn_ioreq_deinit(vm);
+
if (vm->monitor_page) {
put_page(vm->monitor_page);
vm->monitor_page = NULL;
diff --git a/include/uapi/linux/acrn.h b/include/uapi/linux/acrn.h
index d6d026f7454a..0309b087829f 100644
--- a/include/uapi/linux/acrn.h
+++ b/include/uapi/linux/acrn.h
@@ -404,6 +404,19 @@ struct acrn_ioeventfd {
__u64 data;
};

+#define ACRN_IRQFD_FLAG_DEASSIGN 0x01
+/**
+ * struct acrn_irqfd - Data to operate a &struct hsm_irqfd
+ * @fd: The fd of eventfd associated with a hsm_irqfd
+ * @flags: Logical-OR of ACRN_IRQFD_FLAG_*
+ * @msi: Info of MSI associated with the irqfd
+ */
+struct acrn_irqfd {
+ __s32 fd;
+ __u32 flags;
+ struct acrn_msi_entry msi;
+};
+
/* The ioctl type, documented in ioctl-number.rst */
#define ACRN_IOCTL_TYPE 0xA2

@@ -460,5 +473,7 @@ struct acrn_ioeventfd {

#define ACRN_IOCTL_IOEVENTFD \
_IOW(ACRN_IOCTL_TYPE, 0x70, struct acrn_ioeventfd)
+#define ACRN_IOCTL_IRQFD \
+ _IOW(ACRN_IOCTL_TYPE, 0x71, struct acrn_irqfd)

#endif /* _UAPI_ACRN_H */
--
2.28.0
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