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Message-ID: <20200520002055.GC31189@ziepe.ca>
Date: Tue, 19 May 2020 21:20:55 -0300
From: Jason Gunthorpe <jgg@...pe.ca>
To: Alex Williamson <alex.williamson@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
cohuck@...hat.com, peterx@...hat.com
Subject: Re: [PATCH 2/2] vfio: Introduce strict PFNMAP mappings
On Thu, May 14, 2020 at 10:52:09AM -0600, Alex Williamson wrote:
> vfio_unregister_iommu_driver(&vfio_noiommu_ops);
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index 62ba6bd8a486..8d6286d89230 100644
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -61,6 +61,11 @@ module_param_named(dma_entry_limit, dma_entry_limit, uint, 0644);
> MODULE_PARM_DESC(dma_entry_limit,
> "Maximum number of user DMA mappings per container (65535).");
>
> +static bool strict_mmio_maps = true;
> +module_param_named(strict_mmio_maps, strict_mmio_maps, bool, 0644);
> +MODULE_PARM_DESC(strict_mmio_maps,
> + "Restrict DMA mappings of MMIO to those provided by vfio bus drivers supporting invalidation (true).");
> +
This should probably explain that 'false' allows some kind of security
issue and maybe taint the kernel?
Do you think there is a reason to have this anyhow?
Jason
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