On 17.02.20 15:47, Janosch Frank wrote:
> On 2/17/20 12:08 PM, David Hildenbrand wrote:
>>> @@ -4460,6 +4489,10 @@ static long kvm_s390_guest_mem_op(struct kvm_vcpu *vcpu,
>>>
>>> switch (mop->op) {
>>> case KVM_S390_MEMOP_LOGICAL_READ:
>>> + if (kvm_s390_pv_is_protected(vcpu->kvm)) {
>>> + r = -EINVAL;
>>> + break;
>>> + }
>>
>> Could we have a possible race with disabling code, especially while
>> concurrently freeing? (sorry if I ask again, there was just a flood of
>> emails)
see my other reply. Hopefully fixed soon.[...]
>>> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
>>> index 207915488502..0fdee1bc3798 100644
>>> --- a/include/uapi/linux/kvm.h
>>> +++ b/include/uapi/linux/kvm.h
>>> @@ -475,11 +475,15 @@ struct kvm_s390_mem_op {
>>> __u32 op; /* type of operation */
>>> __u64 buf; /* buffer in userspace */
>>> __u8 ar; /* the access register number */
>>> - __u8 reserved[31]; /* should be set to 0 */
>>> + __u8 reserved21[3]; /* should be set to 0 */
>>> + __u32 sida_offset; /* offset into the sida */
>>> + __u8 reserved28[24]; /* should be set to 0 */
>>> };
>>
>> As discussed, I'd prefer an overlaying layout for the sida, as the ar
>> does not make any sense (correct me if I'm wrong :) )
>
> That wouldn't work, because we still check mop->ar < 16 in
> kvm_s390_guest_mem_op(). Also we currently check mop contents twice
> because we overload mem_op() with the SIDA operations.
>
> Using a separate IOCTL is cleaner...
I would rather use the current patch instead of adding a new ioctl.
