David Matlack eccfee4494 KVM: Prevent module exit until all VMs are freed ... commit 5f6de5cbebee925a612856fce6f9182bb3eee0db upstream. Tie the lifetime the KVM module to the lifetime of each VM via kvm.users_count. This way anything that grabs a reference to the VM via kvm_get_kvm() cannot accidentally outlive the KVM module. Prior to this commit, the lifetime of the KVM module was tied to the lifetime of /dev/kvm file descriptors, VM file descriptors, and vCPU file descriptors by their respective file_operations "owner" field. This approach is insufficient because references grabbed via kvm_get_kvm() do not prevent closing any of the aforementioned file descriptors. This fixes a long standing theoretical bug in KVM that at least affects async page faults. kvm_setup_async_pf() grabs a reference via kvm_get_kvm(), and drops it in an asynchronous work callback. Nothing prevents the VM file descriptor from being closed and the KVM module from being unloaded before this callback runs. Fixes: af585b921e ("KVM: Halt vcpu if page it tries to access is swapped out") Fixes: 3d3aab1b97 ("KVM: set owner of cpu and vm file operations") Cc: stable@vger.kernel.org Suggested-by: Ben Gardon <bgardon@google.com> [ Based on a patch from Ben implemented for Google's kernel. ] Signed-off-by: David Matlack <dmatlack@google.com> Message-Id: <20220303183328.1499189-2-dmatlack@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2022-04-08 14:40:38 +02:00
..
kvm	KVM: Prevent module exit until all VMs are freed	2022-04-08 14:40:38 +02:00
lib	Revert "irqbypass: do not start cons/prod when failed connect"	2021-06-03 09:00:34 +02:00
Makefile	treewide: Add SPDX license identifier - Makefile/Kconfig	2019-05-21 10:50:46 +02:00