The branch main has been updated by markj:
URL:
https://cgit.FreeBSD.org/src/commit/?id=a97f683fe3c425b425cf8cc466319f54ea957c20
commit a97f683fe3c425b425cf8cc466319f54ea957c20
Author: Mark Johnston <ma...@freebsd.org>
AuthorDate: 2024-11-05 01:36:06 +0000
Commit: Mark Johnston <ma...@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_ */
