On 17/06/21 09:03, Greg KH wrote:
3. Fd-based solution provides the possibility that a telemetry can
read KVM stats in a less privileged situation.
"possiblity"? Does this work or not? Have you tested it?
I think this is essentially s/that/for/. But more precisely:
3. Compared for example to a ioctl, a separate file descriptor makes it
possible for an external program to read statistics, while maintaining
privilege separation between VMM and telemetry code.
+ snprintf(&kvm_vm_stats_header.id[0], sizeof(kvm_vm_stats_header.id),
+ "kvm-%d", task_pid_nr(current));
Why do you write to this static variable for EVERY read? Shouldn't you
just do it once at open? How can it change?
Wait, it's a single shared variable, what happens when multiple tasks
open this thing and read from it? You race between writing to this
variable here and then:
+ return kvm_stats_read(&kvm_vm_stats_header, &kvm_vm_stats_desc[0],
+ &kvm->stat, sizeof(kvm->stat), user_buffer, size, offset);
Accessing it here.
So how is this really working?
It's not - Jing, kvm_vm_stats_header is small enough that you can store
a copy in struct kvm.
Paolo
