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Date:   Wed, 25 May 2022 09:19:08 -0400
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Subject: Re: [PATCH v8 11/22] KVM: s390: pci: add basic kvm_zdev structure
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To:     Alex Williamson <alex.williamson@redhat.com>
Cc:     linux-s390@vger.kernel.org, cohuck@redhat.com,
        schnelle@linux.ibm.com, farman@linux.ibm.com, pmorel@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,
        jgg@nvidia.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-doc@vger.kernel.org
References: <20220524185907.140285-1-mjrosato@linux.ibm.com>
 <20220524185907.140285-12-mjrosato@linux.ibm.com>
 <20220524165046.69f0d84a.alex.williamson@redhat.com>
From:   Matthew Rosato <mjrosato@linux.ibm.com>
In-Reply-To: <20220524165046.69f0d84a.alex.williamson@redhat.com>
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On 5/24/22 6:50 PM, Alex Williamson wrote:
> On Tue, 24 May 2022 14:58:56 -0400
> Matthew Rosato <mjrosato@linux.ibm.com> wrote:
>> diff --git a/arch/s390/kvm/pci.c b/arch/s390/kvm/pci.c
>> new file mode 100644
>> index 000000000000..21c2be5c2713
>> --- /dev/null
>> +++ b/arch/s390/kvm/pci.c
>> @@ -0,0 +1,36 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * s390 kvm PCI passthrough support
>> + *
>> + * Copyright IBM Corp. 2022
>> + *
>> + *    Author(s): Matthew Rosato <mjrosato@linux.ibm.com>
>> + */
>> +
>> +#include <linux/kvm_host.h>
>> +#include <linux/pci.h>
>> +#include "pci.h"
>> +
>> +static int kvm_s390_pci_dev_open(struct zpci_dev *zdev)
>> +{
>> +	struct kvm_zdev *kzdev;
>> +
>> +	kzdev = kzalloc(sizeof(struct kvm_zdev), GFP_KERNEL);
>> +	if (!kzdev)
>> +		return -ENOMEM;
>> +
>> +	kzdev->zdev = zdev;
>> +	zdev->kzdev = kzdev;
>> +
>> +	return 0;
>> +}
>> +
>> +static void kvm_s390_pci_dev_release(struct zpci_dev *zdev)
>> +{
>> +	struct kvm_zdev *kzdev;
>> +
>> +	kzdev = zdev->kzdev;
>> +	WARN_ON(kzdev->zdev != zdev);
>> +	zdev->kzdev = 0;
> 
> I imagine this should be s/0/NULL/, right?  I feel like there was a
> recent similar discussion, but I can't think of any unique search terms
> to sort it out of my inbox.  Thanks,
> 

Yup, I recall a similar comment on a prior version but I don't recall if 
it was this particular patch or not -- anyway will change