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@xxxxxxxxxxxxx>
---
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?
