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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: tsUrR14kjj1J2JHQO0RWy7t2aHH9JTkU X-Proofpoint-ORIG-GUID: 7JMI7yOl1y5ITORKqxIvwg9AR07YpkSC X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.1011,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2024-02-08_03,2024-02-07_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 priorityscore=1501 phishscore=0 malwarescore=0 lowpriorityscore=0 mlxscore=0 spamscore=0 bulkscore=0 mlxlogscore=813 impostorscore=0 clxscore=1015 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2311290000 definitions=main-2402080066 On 1/31/24 21:58, Eric Farman wrote: > The routine ar_translation() is called by get_vcpu_asce(), which is > called from a handful of places, such as an interception that is > being handled during KVM_RUN processing. In that case, the access > registers of the vcpu had been saved to a host_acrs struct and then > the guest access registers loaded from the KVM_RUN struct prior to > entering SIE. Saving them back to KVM_RUN at this point doesn't do > any harm, since it will be done again at the end of the KVM_RUN > loop when the host access registers are restored. > > But that's not the only path into this code. The MEM_OP ioctl can > be used while specifying an access register, and will arrive here. > > Linux itself doesn't use the access registers for much, but it does > squirrel the thread local storage variable into ACRs 0 and 1 in > copy_thread() [1]. This means that the MEM_OP ioctl may copy > non-zero access registers (the upper- and lower-halves of the TLS > pointer) to the KVM_RUN struct, which will end up getting propogated > to the guest once KVM_RUN ioctls occur. Since these are almost > certainly invalid as far as an ALET goes, an ALET Specification > Exception would be triggered if it were attempted to be used. > > Would you be able to come up with a kvm-unit-test to verify a fix and for regression? Hmmm, maybe a kselftest would be even easier.