Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:18 as permitted sender) client-ip=2620:137:e000::1:18;
Message-ID: <2978f1c7-e299-a385-9ef3-5ee796b134e4@linux.ibm.com>
Date:   Tue, 5 Apr 2022 17:06:23 +0200
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101
 Thunderbird/91.3.0
Subject: Re: [PATCH v5 14/21] KVM: s390: pci: provide routines for
 enabling/disabling interrupt forwarding
Content-Language: en-US
To:     Matthew Rosato <mjrosato@linux.ibm.com>,
        Niklas Schnelle <schnelle@linux.ibm.com>,
        linux-s390@vger.kernel.org
Cc:     alex.williamson@redhat.com, cohuck@redhat.com,
        farman@linux.ibm.com, borntraeger@linux.ibm.com, hca@linux.ibm.com,
        gor@linux.ibm.com, gerald.schaefer@linux.ibm.com,
        agordeev@linux.ibm.com, svens@linux.ibm.com, frankja@linux.ibm.com,
        david@redhat.com, imbrenda@linux.ibm.com, vneethv@linux.ibm.com,
        oberpar@linux.ibm.com, freude@linux.ibm.com, thuth@redhat.com,
        pasic@linux.ibm.com, pbonzini@redhat.com, corbet@lwn.net,
        kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-doc@vger.kernel.org
References: <20220404174349.58530-1-mjrosato@linux.ibm.com>
 <20220404174349.58530-15-mjrosato@linux.ibm.com>
 <9a551f04c3878ecb3a26fed6aff2834fbfe41f18.camel@linux.ibm.com>
 <7196af99-fcfa-c9a6-a245-c15268c6851b@linux.ibm.com>
From:   Pierre Morel <pmorel@linux.ibm.com>
In-Reply-To: <7196af99-fcfa-c9a6-a245-c15268c6851b@linux.ibm.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit
Precedence: bulk


On 4/5/22 15:48, Matthew Rosato wrote:
> On 4/5/22 9:39 AM, Niklas Schnelle wrote:
>> On Mon, 2022-04-04 at 13:43 -0400, Matthew Rosato wrote:
>>> These routines will be wired into a kvm ioctl in order to respond to
>>> requests to enable / disable a device for Adapter Event Notifications /
>>> Adapter Interuption Forwarding.
>>>
>>> Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
>>> ---
>>>   arch/s390/kvm/pci.c      | 247 +++++++++++++++++++++++++++++++++++++++
>>>   arch/s390/kvm/pci.h      |   1 +
>>>   arch/s390/pci/pci_insn.c |   1 +
>>>   3 files changed, 249 insertions(+)
>>>
>>> diff --git a/arch/s390/kvm/pci.c b/arch/s390/kvm/pci.c
>>> index 01bd8a2f503b..f0fd68569a9d 100644
>>> --- a/arch/s390/kvm/pci.c
>>> +++ b/arch/s390/kvm/pci.c
>>> @@ -11,6 +11,7 @@
>>>   #include <linux/pci.h>
>>>   #include <asm/pci.h>
>>>   #include <asm/pci_insn.h>
>>> +#include <asm/pci_io.h>
>>>   #include "pci.h"
>>>   struct zpci_aift *aift;
>>> @@ -152,6 +153,252 @@ int kvm_s390_pci_aen_init(u8 nisc)
>>>       return rc;
>>>   }
>>> +/* Modify PCI: Register floating adapter interruption forwarding */
>>> +static int kvm_zpci_set_airq(struct zpci_dev *zdev)
>>> +{
>>> +    u64 req = ZPCI_CREATE_REQ(zdev->fh, 0, ZPCI_MOD_FC_REG_INT);
>>> +    struct zpci_fib fib = {};
>>
>> Hmm this one uses '{}' as initializer while all current callers of
>> zpci_mod_fc() use '{0}'. As far as I know the empty braces are a GNU
>> extension so should work for the kernel but for consistency I'd go with
>> '{0}' or possibly '{.foo = bar, ...}' where that is more readable.
>> There too uninitialized fields will be set to 0. Unless of course there
>> is a conflicting KVM convention that I don't know about.
> 
> No convention that I'm aware of, I previously had fib = {0} based on the 
> same rationale you describe and changed to fib = {} per review request 
> from Pierre a few versions back.  I don't have a strong preference, but 
> I did not note any functional difference between the two and see a bunch 
> of examples of both methods throughout the kernel.
> 

Was stupid of me to comment that, as you said there are no difference, 
so do as you want.


-- 
Pierre Morel
IBM Lab Boeblingen