Re: [PATCH v2] iommu/dma: Add config for PCI SAC address trick

[Robin Murphy]

On 2022-06-23 12:33, Joerg Roedel wrote:
> On Wed, Jun 22, 2022 at 02:12:39PM +0100, Robin Murphy wrote:
> > Thanks for your bravery!
>
> It already starts, with that patch I am getting:
>
> 	xhci_hcd 0000:02:00.0: AMD-Vi: Event logged [IO_PAGE_FAULT domain=0x000f address=0xff00ffffffefe000 flags=0x0000]
>
> In my kernel log. The device is an AMD XHCI controller and seems to
> funciton normally after boot. The message disappears with
> iommu.forcedac=0.
>
> Need to look more into that...

Given how amd_iommu_domain_alloc() sets the domain aperture, presumably 
the DMA address allocated was 0xffffffffffefe000? Odd that it gets bits 
punched out in the middle rather than simply truncated off the top as I 
would have expected :/

Robin.