Re: [PATCH v3 2/9] Documentation: KVM: s390: Describe KVM_S390_MEMOP_F_CMPXCHG

Bagas Sanjaya
2022-11-18T01:51:09Z

On 11/18/22 05:17, Janis Schoetterl-Glausch wrote:
> +For write accesses, the KVM_S390_MEMOP_F_CMPXCHG might be supported.
> +In this case, instead of doing an unconditional write, the access occurs only
> +if the target location contains the "size" byte long value pointed to by
> +"old_p". This is performed as an atomic cmpxchg. "size" must be a power of two
> +up to and including 16.
> +The value at the target location is written to the location "old_p" points to.
> +If the exchange did not take place because the target value doesn't match the
> +old value KVM_S390_MEMOP_R_NO_XCHG is returned.
> +The KVM_S390_MEMOP_F_CMPXCHG flag is supported if KVM_CAP_S390_MEM_OP_EXTENSION
> +has bit 1 (i.e. bit with value 2) set.
>

Is KVM_S390_MEMOP_F_CMPXCHG supported with conditions (as you implied)?

--
An old man doll... just what I always wanted! - Clara