From: Heiko Carstens <hca@linux.ibm.com>
To: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Michael Mueller <mimu@linux.ibm.com>,
kvm@vger.kernel.org, linux-s390@vger.kernel.org,
Christian Borntraeger <borntraeger@linux.ibm.com>,
Janosch Frank <frankja@linux.ibm.com>,
Claudio Imbrenda <imbrenda@linux.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>,
Viktor Mihajlovski <mihajlov@linux.ibm.com>
Subject: Re: [PATCH] KVM: s390: fix gisa destroy operation might lead to cpu stalls
Date: Wed, 23 Aug 2023 21:29:51 +0200 [thread overview]
Message-ID: <20230823192951.28372-A-hca@linux.ibm.com> (raw)
In-Reply-To: <ZOYtd7m2TqMDIb++@li-008a6a4c-3549-11b2-a85c-c5cc2836eea2.ibm.com>
On Wed, Aug 23, 2023 at 06:01:59PM +0200, Alexander Gordeev wrote:
> On Wed, Aug 23, 2023 at 04:09:26PM +0200, Michael Mueller wrote:
> > Does that make sense for you?
>
> Not really. If process_gib_alert_list() does guarantee the removal,
> then it should be a condition, not the loop.
>
> But I am actually not into this code. Just wanted to point out that
> cpu_relax() is removed from this loop and the two other loops within
> process_gib_alert_list() do not have it either.
Not sure if you are mainly referring to the missing cpu_relax(), however:
any chance you missed that cpu_relax() translates only to barrier() on
s390? So it really doesn't "relax" anything. cpu_relax() used to be a
diagnose 0x44 (aka voluntary yield), but that caused many problems,
therefore we removed that logic, and the only thing remaining is a no-op
with compiler barrier semantics.
prev parent reply other threads:[~2023-08-23 19:30 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-23 12:41 [PATCH] KVM: s390: fix gisa destroy operation might lead to cpu stalls Michael Mueller
2023-08-23 13:23 ` Alexander Gordeev
2023-08-23 14:09 ` Michael Mueller
2023-08-23 16:01 ` Alexander Gordeev
2023-08-23 16:16 ` Claudio Imbrenda
2023-08-24 10:09 ` Michael Mueller
2023-08-23 19:29 ` Heiko Carstens [this message]
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