On Thu May 22, 2025 at 3:22 PM CEST, Claudio Imbrenda wrote:
> All paths leading to handle_essa() already hold the kvm->srcu.
> Remove unneeded srcu locking from handle_essa().
> Add lockdep assertion to make sure we will always be holding kvm->srcu
> when entering handle_essa().
>
> Signed-off-by: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
> Reviewed-by: Nina Schoetterl-Glausch <nsg@xxxxxxxxxxxxx>
> Reviewed-by: Christian Borntraeger <borntraeger@xxxxxxxxxxxxx>
Reviewed-by: Christoph Schlameuss <schlameuss@xxxxxxxxxxxxx>
> ---
> arch/s390/kvm/priv.c | 6 ++----
> 1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c
> index 1a49b89706f8..9253c70897a8 100644
> --- a/arch/s390/kvm/priv.c
> +++ b/arch/s390/kvm/priv.c
> @@ -1248,6 +1248,8 @@ static inline int __do_essa(struct kvm_vcpu *vcpu, const int orc)
>
> static int handle_essa(struct kvm_vcpu *vcpu)
> {
> + lockdep_assert_held(&vcpu->kvm->srcu);
> +
> /* entries expected to be 1FF */
> int entries = (vcpu->arch.sie_block->cbrlo & ~PAGE_MASK) >> 3;
> unsigned long *cbrlo;
> @@ -1297,12 +1299,8 @@ static int handle_essa(struct kvm_vcpu *vcpu)
> /* Retry the ESSA instruction */
> kvm_s390_retry_instr(vcpu);
> } else {
> - int srcu_idx;
> -
> mmap_read_lock(vcpu->kvm->mm);
> - srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
> i = __do_essa(vcpu, orc);
> - srcu_read_unlock(&vcpu->kvm->srcu, srcu_idx);
> mmap_read_unlock(vcpu->kvm->mm);
> if (i < 0)
> return i;
