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Date:   Tue, 24 May 2022 16:50:46 -0600
From:   Alex Williamson <alex.williamson@redhat.com>
To:     Matthew Rosato <mjrosato@linux.ibm.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,
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        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
Subject: Re: [PATCH v8 11/22] KVM: s390: pci: add basic kvm_zdev structure
Message-ID: <20220524165046.69f0d84a.alex.williamson@redhat.com>
In-Reply-To: <20220524185907.140285-12-mjrosato@linux.ibm.com>
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        <20220524185907.140285-12-mjrosato@linux.ibm.com>
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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,

Alex