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Message-ID: <73ecf737-c523-b4ab-f11f-431bb5fb2c37@gmail.com>
Date: Fri, 18 Nov 2022 08:50:54 +0700
From: Bagas Sanjaya <bagasdotme@...il.com>
To: Janis Schoetterl-Glausch <scgl@...ux.ibm.com>,
Christian Borntraeger <borntraeger@...ux.ibm.com>,
Janosch Frank <frankja@...ux.ibm.com>,
Claudio Imbrenda <imbrenda@...ux.ibm.com>,
Heiko Carstens <hca@...ux.ibm.com>,
Vasily Gorbik <gor@...ux.ibm.com>,
Alexander Gordeev <agordeev@...ux.ibm.com>
Cc: David Hildenbrand <david@...hat.com>,
Jonathan Corbet <corbet@....net>, kvm@...r.kernel.org,
linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-kselftest@...r.kernel.org, linux-s390@...r.kernel.org,
Paolo Bonzini <pbonzini@...hat.com>,
Shuah Khan <shuah@...nel.org>,
Sven Schnelle <svens@...ux.ibm.com>
Subject: Re: [PATCH v3 2/9] Documentation: KVM: s390: Describe
KVM_S390_MEMOP_F_CMPXCHG
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
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