Re: [PATCH 1/3] s390x/pci: avoid double enable/disable of aif

[Cédric Le Goater]

On 1/16/24 23:31, Matthew Rosato wrote:
> Use a flag to keep track of whether AIF is currently enabled.  This can be
> used to avoid enabling/disabling AIF multiple times as well as to determine
> whether or not it should be disabled during reset processing.

Why don't we disable AIF always at reset ? Doesn't KVM handle multiple calls
to KVM_S390_ZPCIOP_DEREG_AEN cleanly ? Just asking, I am no expert there.

Thanks,

C.


> Fixes: d0bc7091c2 ("s390x/pci: enable adapter event notification for interpreted 
> devices")
> Reported-by: Cédric Le Goater <clg@redhat.com>
> Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
> ---
>   hw/s390x/s390-pci-kvm.c         | 25 +++++++++++++++++++++++--
>   include/hw/s390x/s390-pci-bus.h |  1 +
>   2 files changed, 24 insertions(+), 2 deletions(-)
>
> diff --git a/hw/s390x/s390-pci-kvm.c b/hw/s390x/s390-pci-kvm.c
> index ff41e4106d..f7e10cfa72 100644
> --- a/hw/s390x/s390-pci-kvm.c
> +++ b/hw/s390x/s390-pci-kvm.c
> @@ -27,6 +27,7 @@ bool s390_pci_kvm_interp_allowed(void)
>   
>   int s390_pci_kvm_aif_enable(S390PCIBusDevice *pbdev, ZpciFib *fib, bool assist)
>   {
> +    int rc;
>       struct kvm_s390_zpci_op args = {
>           .fh = pbdev->fh,
>           .op = KVM_S390_ZPCIOP_REG_AEN,
> @@ -38,15 +39,35 @@ int s390_pci_kvm_aif_enable(S390PCIBusDevice *pbdev, 
> ZpciFib *fib, bool assist)
>           .u.reg_aen.flags = (assist) ? 0 : KVM_S390_ZPCIOP_REGAEN_HOST
>       };
>   
> -    return kvm_vm_ioctl(kvm_state, KVM_S390_ZPCI_OP, &args);
> +    if (pbdev->aif) {
> +        return -EINVAL;
> +    }
> +
> +    rc = kvm_vm_ioctl(kvm_state, KVM_S390_ZPCI_OP, &args);
> +    if (rc == 0) {
> +        pbdev->aif = true;
> +    }
> +
> +    return rc;
>   }
>   
>   int s390_pci_kvm_aif_disable(S390PCIBusDevice *pbdev)
>   {
> +    int rc;
> +
>       struct kvm_s390_zpci_op args = {
>           .fh = pbdev->fh,
>           .op = KVM_S390_ZPCIOP_DEREG_AEN
>       };
>   
> -    return kvm_vm_ioctl(kvm_state, KVM_S390_ZPCI_OP, &args);
> +    if (!pbdev->aif) {
> +        return -EINVAL;
> +    }
> +
> +    rc = kvm_vm_ioctl(kvm_state, KVM_S390_ZPCI_OP, &args);
> +    if (rc == 0) {
> +        pbev->aif = false;
> +    }
> +
> +    return rc;
>   }
> diff --git a/include/hw/s390x/s390-pci-bus.h b/include/hw/s390x/s390-pci-bus.h
> index b1bdbeaeb5..435e788867 100644
> --- a/include/hw/s390x/s390-pci-bus.h
> +++ b/include/hw/s390x/s390-pci-bus.h
> @@ -361,6 +361,7 @@ struct S390PCIBusDevice {
>       bool unplug_requested;
>       bool interp;
>       bool forwarding_assist;
> +    bool aif;
>       QTAILQ_ENTRY(S390PCIBusDevice) link;
>   };
>