linux-kernel - Re: Failure to shutdown/reboot with intel

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Date:   Tue, 12 May 2020 23:13:18 +0200
From:   Joerg Roedel <jroedel@...e.de>
To:     Lenny Szubowicz <lszubowi@...hat.com>
Cc:     Uwe Kleine-König <uwe@...ine-koenig.org>,
        linux-kernel@...r.kernel.org, rafael.j.wysocki@...el.com,
        tglx@...utronix.de, x86@...nel.org,
        Lu Baolu <baolu.lu@...ux.intel.com>
Subject: Re: Failure to shutdown/reboot with intel_iommu=on

Hi Lenny,

On Tue, May 12, 2020 at 04:00:26PM -0400, Lenny Szubowicz wrote:
> Some Lenovo laptops provide an ACPI DMAR RMRR that identifies the memory
> range that the kernel should open up for permissable DMA access
> for this purpose. Unfortunately, the PCI device that performs these
> DMA operations is hidden from the kernel by the BIOS. Given that the
> associated PCI device is hidden, the Linux kernel does not act upon
> the associated DMAR RMRR.

That sounds aweful. We should add to the VT-d driver that it sets up
RMRR mappings for request-ids which are not present as a PCI device, to
fix the Laptops which have it.

For the others, is the region the TPM talks to via DMA known so that we
can add a quirk?


	Joerg