On Tue, 20 Sep 2022 15:30:25 -0400
Matthew Rosato <mjrosato@xxxxxxxxxxxxx> wrote:
> The kvm registration hooks must be registered even if the facilities
> necessary for zPCI interpretation are unavailable, as vfio-pci-zdev will
> expect to use the hooks regardless.
> This fixes an issue where vfio-pci-zdev will fail its open function
> because of a missing kvm_register when running on hardware that does not
> support zPCI interpretation.
>
> Fixes: ca922fecda6c ("KVM: s390: pci: Hook to access KVM lowlevel from VFIO")
> Signed-off-by: Matthew Rosato <mjrosato@xxxxxxxxxxxxx>
Reviewed-by: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
> ---
> arch/s390/kvm/kvm-s390.c | 4 ++--
> arch/s390/kvm/pci.c | 14 +++++++++++---
> 2 files changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index e20e126944aa..5c7f5f97ea09 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -510,7 +510,7 @@ int kvm_arch_init(void *opaque)
> goto out;
> }
>
> - if (kvm_s390_pci_interp_allowed()) {
> + if (IS_ENABLED(CONFIG_VFIO_PCI_ZDEV_KVM)) {
> rc = kvm_s390_pci_init();
> if (rc) {
> pr_err("Unable to allocate AIFT for PCI\n");
> @@ -532,7 +532,7 @@ int kvm_arch_init(void *opaque)
> void kvm_arch_exit(void)
> {
> kvm_s390_gib_destroy();
> - if (kvm_s390_pci_interp_allowed())
> + if (IS_ENABLED(CONFIG_VFIO_PCI_ZDEV_KVM))
> kvm_s390_pci_exit();
> debug_unregister(kvm_s390_dbf);
> debug_unregister(kvm_s390_dbf_uv);
> diff --git a/arch/s390/kvm/pci.c b/arch/s390/kvm/pci.c
> index 90aaba80696a..c50c1645c0ae 100644
> --- a/arch/s390/kvm/pci.c
> +++ b/arch/s390/kvm/pci.c
> @@ -672,23 +672,31 @@ int kvm_s390_pci_zpci_op(struct kvm *kvm, struct kvm_s390_zpci_op *args)
>
> int kvm_s390_pci_init(void)
> {
> + zpci_kvm_hook.kvm_register = kvm_s390_pci_register_kvm;
> + zpci_kvm_hook.kvm_unregister = kvm_s390_pci_unregister_kvm;
> +
> + if (!kvm_s390_pci_interp_allowed())
> + return 0;
> +
> aift = kzalloc(sizeof(struct zpci_aift), GFP_KERNEL);
> if (!aift)
> return -ENOMEM;
>
> spin_lock_init(&aift->gait_lock);
> mutex_init(&aift->aift_lock);
> - zpci_kvm_hook.kvm_register = kvm_s390_pci_register_kvm;
> - zpci_kvm_hook.kvm_unregister = kvm_s390_pci_unregister_kvm;
>
> return 0;
> }
>
> void kvm_s390_pci_exit(void)
> {
> - mutex_destroy(&aift->aift_lock);
> zpci_kvm_hook.kvm_register = NULL;
> zpci_kvm_hook.kvm_unregister = NULL;
>
> + if (!kvm_s390_pci_interp_allowed())
> + return;
> +
> + mutex_destroy(&aift->aift_lock);
> +
> kfree(aift);
> }
