Reserve ioctl number in userpsace-api/ioctl/ioctl-number.rst Introduce MSHV_REQUEST_VERSION ioctl. Introduce documentation for /dev/mshv in Documentation/virt/mshv Signed-off-by: Nuno Das Neves <nunodasneves@xxxxxxxxxxxxxxxxxxx> --- .../userspace-api/ioctl/ioctl-number.rst | 2 + Documentation/virt/mshv/api.rst | 62 +++++++++++++++++++ include/linux/mshv.h | 11 ++++ include/uapi/linux/mshv.h | 19 ++++++ virt/mshv/mshv_main.c | 49 +++++++++++++++ 5 files changed, 143 insertions(+) create mode 100644 Documentation/virt/mshv/api.rst create mode 100644 include/linux/mshv.h create mode 100644 include/uapi/linux/mshv.h diff --git a/Documentation/userspace-api/ioctl/ioctl-number.rst b/Documentation/userspace-api/ioctl/ioctl-number.rst index 55a2d9b2ce33..13a4d3ecafca 100644 --- a/Documentation/userspace-api/ioctl/ioctl-number.rst +++ b/Documentation/userspace-api/ioctl/ioctl-number.rst @@ -343,6 +343,8 @@ Code Seq# Include File Comments 0xB5 00-0F uapi/linux/rpmsg.h <mailto:linux-remoteproc@xxxxxxxxxxxxxxx> 0xB6 all linux/fpga-dfl.h 0xB7 all uapi/linux/remoteproc_cdev.h <mailto:linux-remoteproc@xxxxxxxxxxxxxxx> +0xB8 all uapi/linux/mshv.h Microsoft Hypervisor root partition APIs + <mailto:linux-hyperv@xxxxxxxxxxxxxxx> 0xC0 00-0F linux/usb/iowarrior.h 0xCA 00-0F uapi/misc/cxl.h 0xCA 10-2F uapi/misc/ocxl.h diff --git a/Documentation/virt/mshv/api.rst b/Documentation/virt/mshv/api.rst new file mode 100644 index 000000000000..82e32de48d03 --- /dev/null +++ b/Documentation/virt/mshv/api.rst @@ -0,0 +1,62 @@ +.. SPDX-License-Identifier: GPL-2.0 + +===================================================== +Microsoft Hypervisor Root Partition API Documentation +===================================================== + +1. Overview +=========== + +This document describes APIs for creating and managing guest virtual machines +when running Linux as the root partition on the Microsoft Hypervisor. + +This API is not yet stable. + +2. Glossary/Terms +================= + +hv +-- +Short for Hyper-V. This name is used in the kernel to describe interfaces to +the Microsoft Hypervisor. + +mshv +---- +Short for Microsoft Hypervisor. This is the name of the userland API module +described in this document. + +Partition +--------- +A virtual machine running on the Microsoft Hypervisor. + +Root Partition +-------------- +The partition that is created and assumes control when the machine boots. The +root partition can use mshv APIs to create guest partitions. + +3. API description +================== + +The module is named mshv and can be configured with CONFIG_HYPERV_ROOT_API. + +Mshv is file descriptor-based, following a similar pattern to KVM. + +To get a handle to the mshv driver, use open("/dev/mshv"). + +3.1 MSHV_REQUEST_VERSION +------------------------ +:Type: /dev/mshv ioctl +:Parameters: pointer to a u32 +:Returns: 0 on success + +Before issuing any other ioctls, a MSHV_REQUEST_VERSION ioctl must be called to +establish the interface version with the kernel module. + +The caller should pass the MSHV_VERSION as an argument. + +The kernel module will check which interface versions it supports and return 0 +if one of them matches. + +This /dev/mshv file descriptor will remain 'locked' to that version as long as +it is open - this ioctl can only be called once per open. + diff --git a/include/linux/mshv.h b/include/linux/mshv.h new file mode 100644 index 000000000000..a0982fe2c0b8 --- /dev/null +++ b/include/linux/mshv.h @@ -0,0 +1,11 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +#ifndef _LINUX_MSHV_H +#define _LINUX_MSHV_H + +/* + * Microsoft Hypervisor root partition driver for /dev/mshv + */ + +#include <uapi/linux/mshv.h> + +#endif diff --git a/include/uapi/linux/mshv.h b/include/uapi/linux/mshv.h new file mode 100644 index 000000000000..dd30fc2f0a80 --- /dev/null +++ b/include/uapi/linux/mshv.h @@ -0,0 +1,19 @@ +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ +#ifndef _UAPI_LINUX_MSHV_H +#define _UAPI_LINUX_MSHV_H + +/* + * Userspace interface for /dev/mshv + * Microsoft Hypervisor root partition APIs + */ + +#include <linux/types.h> + +#define MSHV_VERSION 0x0 + +#define MSHV_IOCTL 0xB8 + +/* mshv device */ +#define MSHV_REQUEST_VERSION _IOW(MSHV_IOCTL, 0x00, __u32) + +#endif diff --git a/virt/mshv/mshv_main.c b/virt/mshv/mshv_main.c index ecb9089761fe..62f631f85301 100644 --- a/virt/mshv/mshv_main.c +++ b/virt/mshv/mshv_main.c @@ -11,25 +11,74 @@ #include <linux/module.h> #include <linux/fs.h> #include <linux/miscdevice.h> +#include <linux/slab.h> +#include <linux/mshv.h> MODULE_AUTHOR("Microsoft"); MODULE_LICENSE("GPL"); +#define MSHV_INVALID_VERSION 0xFFFFFFFF +#define MSHV_CURRENT_VERSION MSHV_VERSION + +static u32 supported_versions[] = { + MSHV_CURRENT_VERSION, +}; + +static long +mshv_ioctl_request_version(u32 *version, void __user *user_arg) +{ + u32 arg; + int i; + + if (copy_from_user(&arg, user_arg, sizeof(arg))) + return -EFAULT; + + for (i = 0; i < ARRAY_SIZE(supported_versions); ++i) { + if (supported_versions[i] == arg) { + *version = supported_versions[i]; + return 0; + } + } + return -ENOTSUPP; +} + static long mshv_dev_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg) { + u32 *version = (u32 *)filp->private_data; + + if (ioctl == MSHV_REQUEST_VERSION) { + /* Version can only be set once */ + if (*version != MSHV_INVALID_VERSION) + return -EBADFD; + + return mshv_ioctl_request_version(version, (void __user *)arg); + } + + /* Version must be set before other ioctls can be called */ + if (*version == MSHV_INVALID_VERSION) + return -EBADFD; + + /* TODO other ioctls */ + return -ENOTTY; } static int mshv_dev_open(struct inode *inode, struct file *filp) { + filp->private_data = kmalloc(sizeof(u32), GFP_KERNEL); + if (!filp->private_data) + return -ENOMEM; + *(u32 *)filp->private_data = MSHV_INVALID_VERSION; + return 0; } static int mshv_dev_release(struct inode *inode, struct file *filp) { + kfree(filp->private_data); return 0; } -- 2.25.1
