linux-kernel - Re: [PATCH] zcrypt: handle AP Info notification from CHSC SEI command

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Message-Id: <88b72363-9dca-4653-c326-9c37b6349a32@linux.ibm.com>
Date:   Thu, 31 Jan 2019 18:28:39 -0500
From:   Tony Krowiak <akrowiak@...ux.ibm.com>
To:     Sebastian Ott <sebott@...ux.ibm.com>
Cc:     linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        Martin Schwidefsky <schwidefsky@...ibm.com>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        oberpar@...ux.ibm.com, freude@...ux.ibm.com, pmorel@...ux.ibm.com,
        pasic@...ux.ibm.com, cohuck@...hat.com
Subject: Re: [PATCH] zcrypt: handle AP Info notification from CHSC SEI command

On 1/30/19 1:32 PM, Sebastian Ott wrote:
> On Wed, 30 Jan 2019, Tony Krowiak wrote:
>> +#if IS_ENABLED(CONFIG_ZCRYPT)
>> +void ap_bus_cfg_chg(void);
>> +#else
>> +#error "no CONFIG_ZCRYPT"
>     ^
> I don't think that's the right thing to do here.

I'd like to leave it. If somebody edits .config
and sets CONFIG_ZCRYPT=n, then the build will
fail. The preprocessor error above tells them
why.

> 
> 
>> +++ b/drivers/s390/cio/chsc.h
>> @@ -9,6 +9,7 @@
>>   #include <asm/chsc.h>
>>   #include <asm/schid.h>
>>   #include <asm/qdio.h>
>> +#include <asm/ap.h>
> 
> This should be moved to chsc.c

I can do that, but I'm curious why.

> 
> 
>> +++ b/drivers/s390/crypto/ap_bus.c
>> @@ -35,6 +35,7 @@
>>   #include <linux/mod_devicetable.h>
>>   #include <linux/debugfs.h>
>>   #include <linux/ctype.h>
>> +#include <asm/crw.h>
> 
> This is not needed here.

I'll remove it.

> 
> 
>>   /*
>> +* A config change has happened, Force an ap bus rescan.
>> +*/
>> +void ap_bus_cfg_chg(void)
>> +{
>> +	AP_DBF(DBF_INFO, "%s config change, forcing bus rescan\n", __func__);
>> +
>> +	ap_bus_force_rescan();
>> +}
>> +EXPORT_SYMBOL(ap_bus_cfg_chg);
> 
> There is no need for the export symbol - you don't call that function
> from module code.
> As an unrelated question, just to be sure: ap_bus.c is compiled as
> built-in even with ZCRYPT=m, right?

No. If you edit .config and set CONFIG_ZCRYPT=m, ap_bus.c will be built
into the zcrypt.ko module. Through some other magic, the zcrypt module
is loaded when linux boots.

> 
> Reviewed-by: Sebastian Ott <sebott@...ux.ibm.com>
> 
> Regards,
> Sebastian
>