Date: Tue, 5 Nov 2024 01:40:50 GMT From: Mark Johnston <markj@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: a97f683fe3c4 - main - vmm: Add a device file interface for creating and destroying VMs Message-ID: <202411050140.4A51eoLC062652@gitrepo.freebsd.org>
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The branch main has been updated by markj: URL: https://cgit.FreeBSD.org/src/commit/?id=a97f683fe3c425b425cf8cc466319f54ea957c20 commit a97f683fe3c425b425cf8cc466319f54ea957c20 Author: Mark Johnston <markj@FreeBSD.org> AuthorDate: 2024-11-05 01:36:06 +0000 Commit: Mark Johnston <markj@FreeBSD.org> CommitDate: 2024-11-05 01:40:41 +0000 vmm: Add a device file interface for creating and destroying VMs This supersedes the sysctl interface, which has the limitations of being root-only and not supporting automatic resource destruction, i.e., we cannot easily destroy VMs automatically when bhyve terminates. For now, two ioctls are implemented VMMCTL_VM_CREATE and VMMCTL_VM_DESTROY. Eventually I would like to support tying a VM's lifetime to that of the descriptor, so that it is automatically destroyed when the descriptor is closed. However, this will require some work in bhyve: when the guest wants to reboot, bhyve exits with a status that indicates that it is to be restarted. This is incompatible with the idea of tying a VM's lifetime to that of a descriptor, since we want to avoid creating and destroying a VM across each reboot (as this involves freeing all of the guest memory, among other things). One possible design would be to decompose bhyve into two processes, a parent which handles reboots, and a child which runs in capability mode and handles guest execution. In any case, this gets us closer to addressing the shortcomings mentioned above. Reviewed by: jhb Differential Revision: https://reviews.freebsd.org/D47028 --- sys/amd64/vmm/vmm.c | 4 ++- sys/arm64/vmm/vmm.c | 4 ++- sys/dev/vmm/vmm_dev.c | 80 ++++++++++++++++++++++++++++++++++++++++++++++++++- sys/dev/vmm/vmm_dev.h | 15 +++++++++- 4 files changed, 99 insertions(+), 4 deletions(-) diff --git a/sys/amd64/vmm/vmm.c b/sys/amd64/vmm/vmm.c index 07d3f74b8365..77e0adda86f5 100644 --- a/sys/amd64/vmm/vmm.c +++ b/sys/amd64/vmm/vmm.c @@ -465,7 +465,9 @@ vmm_handler(module_t mod, int what, void *arg) switch (what) { case MOD_LOAD: if (vmm_is_hw_supported()) { - vmmdev_init(); + error = vmmdev_init(); + if (error != 0) + break; error = vmm_init(); if (error == 0) vmm_initialized = 1; diff --git a/sys/arm64/vmm/vmm.c b/sys/arm64/vmm/vmm.c index 4127fad5cd59..2f4f3a2b59ea 100644 --- a/sys/arm64/vmm/vmm.c +++ b/sys/arm64/vmm/vmm.c @@ -362,7 +362,9 @@ vmm_handler(module_t mod, int what, void *arg) switch (what) { case MOD_LOAD: /* TODO: if (vmm_is_hw_supported()) { */ - vmmdev_init(); + error = vmmdev_init(); + if (error != 0) + break; error = vmm_init(); if (error == 0) vmm_initialized = true; diff --git a/sys/dev/vmm/vmm_dev.c b/sys/dev/vmm/vmm_dev.c index a43d642b3925..4bea4360a51c 100644 --- a/sys/dev/vmm/vmm_dev.c +++ b/sys/dev/vmm/vmm_dev.c @@ -8,6 +8,7 @@ #include <sys/param.h> #include <sys/conf.h> +#include <sys/fcntl.h> #include <sys/ioccom.h> #include <sys/jail.h> #include <sys/kernel.h> @@ -917,11 +918,88 @@ SYSCTL_PROC(_hw_vmm, OID_AUTO, create, NULL, 0, sysctl_vmm_create, "A", NULL); -void +static int +vmmctl_open(struct cdev *cdev, int flags, int fmt, struct thread *td) +{ + int error; + + error = vmm_priv_check(td->td_ucred); + if (error != 0) + return (error); + + if ((flags & FWRITE) == 0) + return (EPERM); + + return (0); +} + +static int +vmmctl_ioctl(struct cdev *cdev, u_long cmd, caddr_t data, int fflag, + struct thread *td) +{ + int error; + + switch (cmd) { + case VMMCTL_VM_CREATE: { + struct vmmctl_vm_create *vmc; + + vmc = (struct vmmctl_vm_create *)data; + vmc->name[VM_MAX_NAMELEN] = '\0'; + for (size_t i = 0; i < nitems(vmc->reserved); i++) { + if (vmc->reserved[i] != 0) { + error = EINVAL; + return (error); + } + } + + error = vmmdev_create(vmc->name, td->td_ucred); + break; + } + case VMMCTL_VM_DESTROY: { + struct vmmctl_vm_destroy *vmd; + + vmd = (struct vmmctl_vm_destroy *)data; + vmd->name[VM_MAX_NAMELEN] = '\0'; + for (size_t i = 0; i < nitems(vmd->reserved); i++) { + if (vmd->reserved[i] != 0) { + error = EINVAL; + return (error); + } + } + + error = vmmdev_lookup_and_destroy(vmd->name, td->td_ucred); + break; + } + default: + error = ENOTTY; + break; + } + + return (error); +} + +static struct cdevsw vmmctlsw = { + .d_name = "vmmctl", + .d_version = D_VERSION, + .d_open = vmmctl_open, + .d_ioctl = vmmctl_ioctl, +}; + +int vmmdev_init(void) { + struct cdev *cdev; + int error; + + error = make_dev_p(MAKEDEV_CHECKNAME, &cdev, &vmmctlsw, NULL, + UID_ROOT, GID_WHEEL, 0600, "vmmctl"); + if (error) + return (error); + pr_allow_flag = prison_add_allow(NULL, "vmm", NULL, "Allow use of vmm in a jail."); + + return (0); } int diff --git a/sys/dev/vmm/vmm_dev.h b/sys/dev/vmm/vmm_dev.h index a2dc4d11f359..410066c49cf2 100644 --- a/sys/dev/vmm/vmm_dev.h +++ b/sys/dev/vmm/vmm_dev.h @@ -18,7 +18,7 @@ struct thread; struct vm; struct vcpu; -void vmmdev_init(void); +int vmmdev_init(void); int vmmdev_cleanup(void); int vmmdev_machdep_ioctl(struct vm *vm, struct vcpu *vcpu, u_long cmd, caddr_t data, int fflag, struct thread *td); @@ -54,4 +54,17 @@ extern const size_t vmmdev_machdep_ioctl_count; #endif /* _KERNEL */ +struct vmmctl_vm_create { + char name[VM_MAX_NAMELEN + 1]; + int reserved[16]; +}; + +struct vmmctl_vm_destroy { + char name[VM_MAX_NAMELEN + 1]; + int reserved[16]; +}; + +#define VMMCTL_VM_CREATE _IOWR('V', 0, struct vmmctl_vm_create) +#define VMMCTL_VM_DESTROY _IOWR('V', 1, struct vmmctl_vm_destroy) + #endif /* _DEV_VMM_DEV_H_ */
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