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From: Matthew Garrett <mjg59@google.com>
To: linux-efi <linux-efi@vger.kernel.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	x86@kernel.org, linux-pci@vger.kernel.org,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] [EFI,PCI] Allow disabling PCI busmastering on bridges during boot
Date: Mon, 2 Dec 2019 16:42:57 -0800
Message-ID: <CACdnJus7nHdr4p4H1j5as9eB=FG-uX+wy_tjvTQ5ObErDJHdow@mail.gmail.com> (raw)
In-Reply-To: <20191203004043.174977-1-matthewgarrett@google.com>

On Mon, Dec 2, 2019 at 4:40 PM Matthew Garrett
<matthewgarrett@google.com> wrote:
>
> Add an option to disable the busmaster bit in the control register on
> all PCI bridges before calling ExitBootServices() and passing control to
> the runtime kernel. System firmware may configure the IOMMU to prevent
> malicious PCI devices from being able to attack the OS via DMA. However,
> since firmware can't guarantee that the OS is IOMMU-aware, it will tear
> down IOMMU configuration when ExitBootServices() is called. This leaves
> a window between where a hostile device could still cause damage before
> Linux configures the IOMMU again.

I don't know enough about ARM to know if this makes sense there as well. Anyone?

  reply index

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-03  0:40 Matthew Garrett
2019-12-03  0:42 ` Matthew Garrett [this message]
2019-12-03 11:54   ` Ard Biesheuvel
2019-12-03 13:38     ` Laszlo Ersek
2019-12-03 19:36       ` Matthew Garrett
2019-12-03 19:40     ` Matthew Garrett
2019-12-04  7:11       ` Laszlo Ersek
2019-12-04 19:29         ` Matthew Garrett
2019-12-03 15:30 ` Andy Lutomirski
2019-12-03 16:33   ` Ard Biesheuvel
2019-12-03 19:41   ` Matthew Garrett
2019-12-04 19:50     ` Andy Lutomirski
2019-12-04 19:56       ` Matthew Garrett
2019-12-12 15:46         ` Ard Biesheuvel
2019-12-13 21:24           ` Matthew Garrett
2019-12-03 18:23 ` kbuild test robot
2019-12-05 13:04 ` kbuild test robot

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