From: Christian Borntraeger <borntraeger@de.ibm.com>
To: David Hildenbrand <david@redhat.com>, Cornelia Huck <cohuck@redhat.com>
Cc: Janosch Frank <frankja@linux.vnet.ibm.com>,
KVM <kvm@vger.kernel.org>,
linux-s390 <linux-s390@vger.kernel.org>,
Qian Cai <cailca@icloud.com>, Pierre Morel <pmorel@linux.ibm.com>,
Tony Krowiak <akrowiak@linux.ibm.com>
Subject: Re: [PATCH] KVM: s390: Remove false WARN_ON_ONCE for the PQAP instruction
Date: Tue, 5 May 2020 10:27:16 +0200 [thread overview]
Message-ID: <480b0bff-8eb5-f75c-a3ce-2555e38917ee@de.ibm.com> (raw)
In-Reply-To: <59f1b90c-47d6-2661-0e99-548a53c9bcd6@redhat.com>
On 05.05.20 10:04, David Hildenbrand wrote:
> On 05.05.20 09:55, Christian Borntraeger wrote:
>>
>>
>> On 05.05.20 09:53, Cornelia Huck wrote:
>>> On Tue, 5 May 2020 09:35:25 +0200
>>> Christian Borntraeger <borntraeger@de.ibm.com> wrote:
>>>
>>>> In LPAR we will only get an intercept for FC==3 for the PQAP
>>>> instruction. Running nested under z/VM can result in other intercepts as
>>>> well, for example PQAP(QCI). So the WARN_ON_ONCE is not right. Let
>>>> us simply remove it.
>>>
>>> While I agree with removing the WARN_ON_ONCE, I'm wondering why z/VM
>>> gives us intercepts for those fcs... is that just a result of nesting
>>> (or the z/VM implementation), or is there anything we might want to do?
>>
>> Yes nesting.
>> The ECA bit for interpretion is an effective one. So if the ECA bit is off
>> in z/VM (no crypto cards) our ECA bit is basically ignored as these bits
>> are ANDed.
>> I asked Tony to ask the z/VM team if that is the case here.
>>
>
> So we can't detect if we have support for ECA_APIE, because there is no
> explicit feature bit, right? Rings a bell. Still an ugly
> hardware/firmware specification.
Yes, no matter if this is the case here, we cannot rely on ECA_APIE to not
trigger intercepts. So we must remove the WARN_ON.
cc stable?
>
> Seems to be the right thing to do
>
> Reviewed-by: David Hildenbrand <david@redhat.com>
>
next prev parent reply other threads:[~2020-05-05 8:27 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-05 7:35 [PATCH] KVM: s390: Remove false WARN_ON_ONCE for the PQAP instruction Christian Borntraeger
2020-05-05 7:53 ` Cornelia Huck
2020-05-05 7:55 ` Christian Borntraeger
2020-05-05 8:04 ` David Hildenbrand
2020-05-05 8:27 ` Christian Borntraeger [this message]
2020-05-05 8:28 ` David Hildenbrand
2020-05-05 8:33 ` Cornelia Huck
2020-05-05 12:18 ` Pierre Morel
2020-05-05 12:31 ` Christian Borntraeger
2020-05-05 8:21 ` Cornelia Huck
2020-05-05 22:34 ` Tony Krowiak
2020-05-06 6:08 ` Christian Borntraeger
2020-05-06 23:29 ` Tony Krowiak
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=480b0bff-8eb5-f75c-a3ce-2555e38917ee@de.ibm.com \
--to=borntraeger@de.ibm.com \
--cc=akrowiak@linux.ibm.com \
--cc=cailca@icloud.com \
--cc=cohuck@redhat.com \
--cc=david@redhat.com \
--cc=frankja@linux.vnet.ibm.com \
--cc=kvm@vger.kernel.org \
--cc=linux-s390@vger.kernel.org \
--cc=pmorel@linux.ibm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).