On 1/10/23 21:26, Janis Schoetterl-Glausch wrote:
User space can use the MEM_OP ioctl to make storage key checked reads and writes to the guest, however, it has no way of performing atomic, key checked, accesses to the guest. Extend the MEM_OP ioctl in order to allow for this, by adding a cmpxchg mode. For now, support this mode for absolute accesses only.
This mode can be use, for example, to set the device-state-change indicator and the adapter-local-summary indicator atomically.
Signed-off-by: Janis Schoetterl-Glausch scgl@linux.ibm.com
include/uapi/linux/kvm.h | 7 +++ arch/s390/kvm/gaccess.h | 3 ++ arch/s390/kvm/gaccess.c | 102 +++++++++++++++++++++++++++++++++++++++ arch/s390/kvm/kvm-s390.c | 41 +++++++++++++++- 4 files changed, 151 insertions(+), 2 deletions(-)
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 55155e262646..452f43c1cc34 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -583,6 +583,8 @@ struct kvm_s390_mem_op { struct { __u8 ar; /* the access register number */ __u8 key; /* access key, ignored if flag unset */
__u8 pad1[6]; /* ignored */__u64 old_addr; /* ignored if flag unset */
These 3 are only used for flag values >=4, no? They aren't used for all flag values but for specific ones, right?