From: Heiko Carstens <hca@linux.ibm.com>
To: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>,
Janosch Frank <frankja@linux.ibm.com>,
David Hildenbrand <david@redhat.com>,
kvm@vger.kernel.org, linux-s390@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/3] KVM: s390: Remove one byte cmpxchg() usage
Date: Mon, 25 Nov 2024 14:37:55 +0100 [thread overview]
Message-ID: <20241125133755.14417-D-hca@linux.ibm.com> (raw)
In-Reply-To: <20241125131617.13be742d@p-imbrenda>
On Mon, Nov 25, 2024 at 01:16:17PM +0100, Claudio Imbrenda wrote:
> On Mon, 25 Nov 2024 12:50:38 +0100
> Heiko Carstens <hca@linux.ibm.com> wrote:
> > @@ -128,23 +126,16 @@ static void sca_clear_ext_call(struct kvm_vcpu *vcpu)
> > struct esca_block *sca = vcpu->kvm->arch.sca;
> > union esca_sigp_ctrl *sigp_ctrl =
> > &(sca->cpu[vcpu->vcpu_id].sigp_ctrl);
> > - union esca_sigp_ctrl old;
> >
> > - old = READ_ONCE(*sigp_ctrl);
> > - expect = old.value;
> > - rc = cmpxchg(&sigp_ctrl->value, old.value, 0);
> > + WRITE_ONCE(sigp_ctrl->value, 9);
>
> that's supposed to be a 0, right?
Duh... yes, of course. I added the "9" to better find the corresponding
code in assembly, and obviously forgot to replace it with 0 again.
Thanks for pointing this out!
Strange enough this still worked. Hmm.
next prev parent reply other threads:[~2024-11-25 13:38 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-11-25 11:50 [PATCH 0/3] KVM: s390: Couple of small cmpxchg() optimizations Heiko Carstens
2024-11-25 11:50 ` [PATCH 1/3] KVM: s390: Use try_cmpxchg() instead of cmpxchg() loops Heiko Carstens
2024-11-25 12:18 ` Claudio Imbrenda
2024-11-25 11:50 ` [PATCH 2/3] KVM: s390: Remove one byte cmpxchg() usage Heiko Carstens
2024-11-25 12:16 ` Claudio Imbrenda
2024-11-25 13:37 ` Heiko Carstens [this message]
2024-11-25 16:20 ` Claudio Imbrenda
2024-11-25 11:50 ` [PATCH 3/3] KVM: s390: Increase size of union sca_utility to four bytes Heiko Carstens
2024-11-25 12:20 ` Claudio Imbrenda
2024-11-25 13:40 ` Heiko Carstens
2024-11-25 16:17 ` Claudio Imbrenda
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