Re: [PATCH 3/4] KVM: introduce memory transaction semaphore

Paolo Bonzini
2022-10-23T17:51:07Z

On 10/22/22 17:48, Emanuele Giuseppe Esposito wrote:
> +static DECLARE_RWSEM(memory_transaction);

This cannot be global, it must be per-struct kvm. Otherwise one VM can
keep the rwsem indefinitely while a second VM hangs in
KVM_KICK_ALL_RUNNING_VCPUS.

It can also be changed to an SRCU (with the down_write+up_write sequence
changed to synchronize_srcu_expedited) which has similar characteristics
to your use of the rwsem.

Paolo