[PATCH v3 3/6] KVM: Get an fd before creating the VM

Oliver Upton
2022-07-20T09:23:35Z

Allocate a VM's fd at the very beginning of kvm_dev_ioctl_create_vm() so
that KVM can use the fd value to generate strigns, e.g. for debugfs,
when creating and initializing the VM.

Signed-off-by: Oliver Upton <oupton@google.com>
---
virt/kvm/kvm_main.c | 30 +++++++++++++++++-------------
1 file changed, 17 insertions(+), 13 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 1f78b7ad5430..e270cff3c9f4 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -4889,25 +4889,27 @@ EXPORT_SYMBOL_GPL(file_is_kvm);

static int kvm_dev_ioctl_create_vm(unsigned long type)
{
- int r;
+ int r, fd;
struct kvm *kvm;
struct file *file;

+ fd = get_unused_fd_flags(O_CLOEXEC);
+ if (fd < 0)
+ return fd;
+
kvm = kvm_create_vm(type);
- if (IS_ERR(kvm))
- return PTR_ERR(kvm);
+ if (IS_ERR(kvm)) {
+ r = PTR_ERR(kvm);
+ goto put_fd;
+ }
+
#ifdef CONFIG_KVM_MMIO
r = kvm_coalesced_mmio_init(kvm);
if (r < 0)
goto put_kvm;
#endif
- r = get_unused_fd_flags(O_CLOEXEC);
- if (r < 0)
- goto put_kvm;
-
file = anon_inode_getfile("kvm-vm", &kvm_vm_fops, kvm, O_RDWR);
if (IS_ERR(file)) {
- put_unused_fd(r);
r = PTR_ERR(file);
goto put_kvm;
}
@@ -4918,18 +4920,20 @@ static int kvm_dev_ioctl_create_vm(unsigned long type)
* cases it will be called by the final fput(file) and will take
* care of doing kvm_put_kvm(kvm).
*/
- if (kvm_create_vm_debugfs(kvm, r) < 0) {
- put_unused_fd(r);
+ if (kvm_create_vm_debugfs(kvm, fd) < 0) {
fput(file);
- return -ENOMEM;
+ r = -ENOMEM;
+ goto put_fd;
}
kvm_uevent_notify_change(KVM_EVENT_CREATE_VM, kvm);

- fd_install(r, file);
- return r;
+ fd_install(fd, file);
+ return fd;

put_kvm:
kvm_put_kvm(kvm);
+put_fd:
+ put_unused_fd(fd);
return r;
}

--
2.37.0.170.g444d1eabd0-goog