Re: [PATCH v2 3/6] kvm: s390: Reject KVM_SET_GSI_ROUTING on ucontrol VMs

[Hariharan Mari <hari55@linux.ibm.com>]

On 2024-12-16 10:21, Christoph Schlameuss wrote:
> Prevent null pointer dereference when processing
> KVM_IRQ_ROUTING_S390_ADAPTER routing entries.
> The ioctl cannot be processed for ucontrol VMs.
> 
> Fixes: f65470661f36 ("KVM: s390/interrupt: do not pin adapter interrupt 
> pages")
> Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>

Tested-by: Hariharan Mari <hari55@linux.ibm.com>
> ---
>  Documentation/virt/kvm/api.rst | 3 +++
>  arch/s390/kvm/interrupt.c      | 2 ++
>  2 files changed, 5 insertions(+)
> 
> diff --git a/Documentation/virt/kvm/api.rst 
> b/Documentation/virt/kvm/api.rst
> index 454c2aaa155e..f15b61317aad 100644
> --- a/Documentation/virt/kvm/api.rst
> +++ b/Documentation/virt/kvm/api.rst
> @@ -1914,6 +1914,9 @@ No flags are specified so far, the corresponding
> field must be set to zero.
>    #define KVM_IRQ_ROUTING_HV_SINT 4
>    #define KVM_IRQ_ROUTING_XEN_EVTCHN 5
> 
> +On s390, adding a KVM_IRQ_ROUTING_S390_ADAPTER is rejected on ucontrol 
> VMs with
> +error -EINVAL.
> +
>  flags:
> 
>  - KVM_MSI_VALID_DEVID: used along with KVM_IRQ_ROUTING_MSI routing 
> entry
> diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
> index 22d73c13e555..d4f031e086fc 100644
> --- a/arch/s390/kvm/interrupt.c
> +++ b/arch/s390/kvm/interrupt.c
> @@ -2898,6 +2898,8 @@ int kvm_set_routing_entry(struct kvm *kvm,
>  	switch (ue->type) {
>  	/* we store the userspace addresses instead of the guest addresses */
>  	case KVM_IRQ_ROUTING_S390_ADAPTER:
> +		if (kvm_is_ucontrol(kvm))
> +			return -EINVAL;
>  		e->set = set_adapter_int;
>  		uaddr =  gmap_translate(kvm->arch.gmap, ue->u.adapter.summary_addr);
>  		if (uaddr == -EFAULT)