linux-kernel - Re: [PATCH v8 1/4] vfio: Do not allow !ops->dma_unmap in vfio_pin/unpin

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Date:   Wed, 26 Jul 2023 11:33:49 -0600
From:   Alex Williamson <alex.williamson@...hat.com>
To:     Nicolin Chen <nicolinc@...dia.com>
Cc:     <jgg@...dia.com>, <kevin.tian@...el.com>, <yi.l.liu@...el.com>,
        <joro@...tes.org>, <will@...nel.org>, <robin.murphy@....com>,
        <shuah@...nel.org>, <linux-kernel@...r.kernel.org>,
        <iommu@...ts.linux.dev>, <kvm@...r.kernel.org>,
        <linux-kselftest@...r.kernel.org>, <mjrosato@...ux.ibm.com>,
        <farman@...ux.ibm.com>
Subject: Re: [PATCH v8 1/4] vfio: Do not allow !ops->dma_unmap in
 vfio_pin/unpin_pages()

On Mon, 24 Jul 2023 12:47:04 -0700
Nicolin Chen <nicolinc@...dia.com> wrote:

> A driver that doesn't implement ops->dma_unmap shouldn't be allowed to do
> vfio_pin/unpin_pages(), though it can use vfio_dma_rw() to access an iova
> range. Deny !ops->dma_unmap cases in vfio_pin/unpin_pages().
> 
> Suggested-by: Kevin Tian <kevin.tian@...el.com>
> Reviewed-by: Kevin Tian <kevin.tian@...el.com>
> Reviewed-by: Yi Liu <yi.l.liu@...el.com>
> Reviewed-by: Jason Gunthorpe <jgg@...dia.com>
> Signed-off-by: Nicolin Chen <nicolinc@...dia.com>
> ---
>  drivers/vfio/vfio_main.c | 4 ++++
>  1 file changed, 4 insertions(+)

I assume these go through iommufd.

Reviewed-by: Alex Williamson <alex.williamson@...hat.com>

> 
> diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
> index 902f06e52c48..0da8ed81a97d 100644
> --- a/drivers/vfio/vfio_main.c
> +++ b/drivers/vfio/vfio_main.c
> @@ -1483,6 +1483,8 @@ int vfio_pin_pages(struct vfio_device *device, dma_addr_t iova,
>  	/* group->container cannot change while a vfio device is open */
>  	if (!pages || !npage || WARN_ON(!vfio_assert_device_open(device)))
>  		return -EINVAL;
> +	if (!device->ops->dma_unmap)
> +		return -EINVAL;
>  	if (vfio_device_has_container(device))
>  		return vfio_device_container_pin_pages(device, iova,
>  						       npage, prot, pages);
> @@ -1520,6 +1522,8 @@ void vfio_unpin_pages(struct vfio_device *device, dma_addr_t iova, int npage)
>  {
>  	if (WARN_ON(!vfio_assert_device_open(device)))
>  		return;
> +	if (WARN_ON(!device->ops->dma_unmap))
> +		return;
>  
>  	if (vfio_device_has_container(device)) {
>  		vfio_device_container_unpin_pages(device, iova, npage);