On 2024-12-16 10:21, Christoph Schlameuss wrote:

Prevent null pointer dereference when processing the KVM_DEV_FLIC_APF_ENABLE and KVM_DEV_FLIC_APF_DISABLE_WAIT ioctls in the interrupt controller.

Fixes: 3c038e6be0e2 ("KVM: async_pf: Async page fault support on s390") Reported-by: Claudio Imbrenda imbrenda@linux.ibm.com Signed-off-by: Christoph Schlameuss schlameuss@linux.ibm.com

Tested-by: Hariharan Mari hari55@linux.ibm.com

---

Documentation/virt/kvm/devices/s390_flic.rst | 4 ++++ arch/s390/kvm/interrupt.c | 4 ++++ 2 files changed, 8 insertions(+)

diff --git a/Documentation/virt/kvm/devices/s390_flic.rst b/Documentation/virt/kvm/devices/s390_flic.rst index ea96559ba501..b784f8016748 100644 --- a/Documentation/virt/kvm/devices/s390_flic.rst +++ b/Documentation/virt/kvm/devices/s390_flic.rst @@ -58,11 +58,15 @@ Groups: Enables async page faults for the guest. So in case of a major page fault the host is allowed to handle this async and continues the guest.

• -EINVAL is returned when called on the FLIC of a ucontrol VM.
• KVM_DEV_FLIC_APF_DISABLE_WAIT Disables async page faults for the guest and waits until already

pending async page faults are done. This is necessary to trigger a completion interrupt for every init interrupt before migrating the interrupt list.

• -EINVAL is returned when called on the FLIC of a ucontrol VM.
• KVM_DEV_FLIC_ADAPTER_REGISTER Register an I/O adapter interrupt source. Takes a

kvm_s390_io_adapter describing the adapter to register:: diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c index ea8dce299954..22d73c13e555 100644 --- a/arch/s390/kvm/interrupt.c +++ b/arch/s390/kvm/interrupt.c @@ -2678,9 +2678,13 @@ static int flic_set_attr(struct kvm_device *dev, struct kvm_device_attr *attr) kvm_s390_clear_float_irqs(dev->kvm); break; case KVM_DEV_FLIC_APF_ENABLE:

• if (kvm_is_ucontrol(dev->kvm))
  

• 	return -EINVAL;
  

  dev->kvm->arch.gmap->pfault_enabled = 1; break; case KVM_DEV_FLIC_APF_DISABLE_WAIT:

• if (kvm_is_ucontrol(dev->kvm))
  

• 	return -EINVAL;
  

  dev->kvm->arch.gmap->pfault_enabled = 0; /*
  • Make sure no async faults are in transition when