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Date:   Mon, 1 Feb 2021 18:14:54 +0100
From:   Cornelia Huck <cohuck@redhat.com>
To:     Max Gurtovoy <mgurtovoy@nvidia.com>
Cc:     <jgg@nvidia.com>, <kvm@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <alex.williamson@redhat.com>,
        <liranl@nvidia.com>, <oren@nvidia.com>, <tzahio@nvidia.com>,
        <leonro@nvidia.com>, <yarong@nvidia.com>, <aviadye@nvidia.com>,
        <shahafs@nvidia.com>, <artemp@nvidia.com>, <kwankhede@nvidia.com>,
        <ACurrid@nvidia.com>, <gmataev@nvidia.com>, <cjia@nvidia.com>,
        <mjrosato@linux.ibm.com>, <yishaih@nvidia.com>, <aik@ozlabs.ru>
Subject: Re: [PATCH 8/9] vfio/pci: use x86 naming instead of igd
Message-ID: <20210201181454.22112b57.cohuck@redhat.com>
In-Reply-To: <20210201162828.5938-9-mgurtovoy@nvidia.com>
References: <20210201162828.5938-1-mgurtovoy@nvidia.com>
        <20210201162828.5938-9-mgurtovoy@nvidia.com>
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On Mon, 1 Feb 2021 16:28:27 +0000
Max Gurtovoy <mgurtovoy@nvidia.com> wrote:

> This patch doesn't change any logic but only align to the concept of
> vfio_pci_core extensions. Extensions that are related to a platform
> and not to a specific vendor of PCI devices should be part of the core
> driver. Extensions that are specific for PCI device vendor should go
> to a dedicated vendor vfio-pci driver.

My understanding is that igd means support for Intel graphics, i.e. a
strict subset of x86. If there are other future extensions that e.g.
only make sense for some devices found only on AMD systems, I don't
think they should all be included under the same x86 umbrella.

Similar reasoning for nvlink, that only seems to cover support for some
GPUs under Power, and is not a general platform-specific extension IIUC.

We can arguably do the zdev -> s390 rename (as zpci appears only on
s390, and all PCI devices will be zpci on that platform), although I'm
not sure about the benefit.

> 
> For now, x86 extensions will include only igd.
> 
> Signed-off-by: Max Gurtovoy <mgurtovoy@nvidia.com>
> ---
>  drivers/vfio/pci/Kconfig                            | 13 ++++++-------
>  drivers/vfio/pci/Makefile                           |  2 +-
>  drivers/vfio/pci/vfio_pci_core.c                    |  2 +-
>  drivers/vfio/pci/vfio_pci_private.h                 |  2 +-
>  drivers/vfio/pci/{vfio_pci_igd.c => vfio_pci_x86.c} |  0
>  5 files changed, 9 insertions(+), 10 deletions(-)
>  rename drivers/vfio/pci/{vfio_pci_igd.c => vfio_pci_x86.c} (100%)

(...)

> diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
> index c559027def2d..e0e258c37fb5 100644
> --- a/drivers/vfio/pci/vfio_pci_core.c
> +++ b/drivers/vfio/pci/vfio_pci_core.c
> @@ -328,7 +328,7 @@ static int vfio_pci_enable(struct vfio_pci_device *vdev)
>  
>  	if (vfio_pci_is_vga(pdev) &&
>  	    pdev->vendor == PCI_VENDOR_ID_INTEL &&
> -	    IS_ENABLED(CONFIG_VFIO_PCI_IGD)) {
> +	    IS_ENABLED(CONFIG_VFIO_PCI_X86)) {
>  		ret = vfio_pci_igd_init(vdev);

This one explicitly checks for Intel devices, so I'm not sure why you
want to generalize this to x86?

>  		if (ret && ret != -ENODEV) {
>  			pci_warn(pdev, "Failed to setup Intel IGD regions\n");