Messages in this thread | ![/](/images/icornerl.gif) | | Date | Wed, 11 Jan 2023 10:38:28 +0100 | Subject | Re: [PATCH v5 01/10] KVM: s390: Extend MEM_OP ioctl by storage key checked cmpxchg | From | Janosch Frank <> |
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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?
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