On 13.05.2024 10:44, Roger Pau Monné wrote: > On Fri, May 10, 2024 at 09:09:54PM -0700, Elliott Mitchell wrote: >> On Thu, Apr 18, 2024 at 09:33:31PM -0700, Elliott Mitchell wrote: >>> >>> I suspect this is a case of there is some step which is missing from >>> Xen's IOMMU handling. Perhaps something which Linux does during an early >>> DMA setup stage, but the current Xen implementation does lazily? >>> Alternatively some flag setting or missing step? >>> >>> I should be able to do another test approach in a few weeks, but I would >>> love if something could be found sooner. >> >> Turned out to be disturbingly easy to get the first entry when it >> happened. Didn't even need `dbench`, it simply showed once the OS was >> fully loaded. I did get some additional data points. >> >> Appears this requires an AMD IOMMUv2. A test system with known >> functioning AMD IOMMUv1 didn't display the issue at all. >> >> (XEN) AMD-Vi: IO_PAGE_FAULT: DDDD:bb:dd.f d0 addr fffffffdf8000000 flags 0x8 >> I > > I would expect the address field to contain more information about the > fault, but I'm not finding any information on the AMD-Vi specification > apart from that it contains the DVA, which makes no sense when the > fault is caused by an interrupt.
Isn't the address above in the "magic" HT range (and hence still meaningful as an address)? Jan
