linux-kernel - Re: [PATCH] s390/kvm: avoid hypfs error message

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Date:   Mon, 20 Jun 2022 11:25:56 +0200
From:   Juergen Gross <jgross@...e.com>
To:     Heiko Carstens <hca@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>
Cc:     linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Sven Schnelle <svens@...ux.ibm.com>
Subject: Re: [PATCH] s390/kvm: avoid hypfs error message

On 20.06.22 11:19, Heiko Carstens wrote:
> On Mon, Jun 20, 2022 at 09:18:37AM +0200, Christian Borntraeger wrote:
>> Am 20.06.22 um 08:03 schrieb Juergen Gross:
>>> Ping?
>>>
>>> On 07.06.22 14:33, Juergen Gross wrote:
>>>> When booting under KVM the following error messages are issued:
>>>>
>>>> hypfs.7f5705: The hardware system does not support hypfs
>>>> hypfs.7a79f0: Initialization of hypfs failed with rc=-61
>>>>
>>>> While being documented, they can easily be avoided by bailing out of
>>>> hypfs_init() early in case of running as a KVM guest.
>>>>
>>>> Signed-off-by: Juergen Gross <jgross@...e.com>
>>>> ---
>>>>    arch/s390/hypfs/inode.c | 3 +++
>>>>    1 file changed, 3 insertions(+)
>>>>
>>>> diff --git a/arch/s390/hypfs/inode.c b/arch/s390/hypfs/inode.c
>>>> index 5c97f48cea91..bdf078f3c641 100644
>>>> --- a/arch/s390/hypfs/inode.c
>>>> +++ b/arch/s390/hypfs/inode.c
>>>> @@ -464,6 +464,9 @@ static int __init hypfs_init(void)
>>>>    {
>>>>        int rc;
>>>> +    if (MACHINE_IS_KVM)
>>>> +        return -ENODATA;
>>>> +
>>>>        hypfs_dbfs_init();
>>>>        if (hypfs_diag_init()) {
>>
>> In case KVM implements hypfs this check would then be wrong.
>> Question to people on CC/TO.
>> Would it be an option to still check with KVM but avoid the error message.
>> So basically changing hypfs_diag_init and fail_dbfs_exit to check
>> for KVM on error?
>> Or is this worse?
> 
> I'd say just move the pr_err("Initialization of hypfs failed with...")
> one label above to fail_hypfs_diag_exit. Then we still get the message
> that the hardware system doesn't support hypfs, which seems to be
> wanted, and the error message only appears for an error.
> 
> Even though I personally dislike printing everything to the console
> this seems to be what is/was preferred. So let's keep that.

Works for me.

Would you be fine with additionally:

@@ __init int hypfs_diag_init(void)
          int rc;

          if (diag204_probe()) {
-                pr_err("The hardware system does not support hypfs\n");
+                pr_info("The hardware system does not support hypfs\n");
                  return -ENODATA;
          }

As this not really an error.


Juergen

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