On 27.03.2024 03:53, Marek Marczykowski-Górecki wrote:
> The IOMMU driver checks if RMRR/IVMD are marked as reserved in memory
> map. This should be true for addresses coming from the firmware, but
> when extra pages used by Xen itself are included in the mapping, those
> are taken from usable RAM used. Mark those pages as reserved too.
>
> Not marking the pages as reserved didn't caused issues before due to
> another a bug in IOMMU driver code, that was fixed in 83afa3135830
> ("amd-vi: fix IVMD memory type checks").
>
> Failing to reserve memory will lead to panic in IOMMU setup code. And
> not including the page in IOMMU mapping will lead to broken console (due
> to IOMMU faults). The pages chosen by the XHCI console driver should
> still be usable by the CPU though, and the console code already can deal
> with too slow console by dropping characters (and console not printing
> anything is a special case of "slow"). When reserving fails print an error
> message showing which pages failed and who requested them. This should
> be enough hint to find why XHCI console doesn't work.
>
> Fixes: 3a1a7b809ffa "drivers/char: mark DMA buffers as reserved for the XHCI"
> Signed-off-by: Marek Marczykowski-Górecki <marma...@invisiblethingslab.com>
Acked-by: Jan Beulich <jbeul...@suse.com>
