On Mon, Apr 12, 2021 at 01:27:35PM -0700, Saeed Mirzamohammadi wrote: > The IOMMU driver calculates the guest addressability for a DMA request > based on the value of the mgaw reported from the IOMMU. However, this > is a fused value and as mentioned in the spec, the guest width > should be calculated based on the minimum of supported adjusted guest > address width (SAGAW) and MGAW. > > This is from specification: > "Guest addressability for a given DMA request is limited to the > minimum of the value reported through this field and the adjusted > guest address width of the corresponding page-table structure. > (Adjusted guest address widths supported by hardware are reported > through the SAGAW field)." > > This causes domain initialization to fail and following > errors appear for EHCI PCI driver: > > [ 2.486393] ehci-pci 0000:01:00.4: EHCI Host Controller > [ 2.486624] ehci-pci 0000:01:00.4: new USB bus registered, assigned bus > number 1 > [ 2.489127] ehci-pci 0000:01:00.4: DMAR: Allocating domain failed > [ 2.489350] ehci-pci 0000:01:00.4: DMAR: 32bit DMA uses non-identity > mapping > [ 2.489359] ehci-pci 0000:01:00.4: can't setup: -12 > [ 2.489531] ehci-pci 0000:01:00.4: USB bus 1 deregistered > [ 2.490023] ehci-pci 0000:01:00.4: init 0000:01:00.4 fail, -12 > [ 2.490358] ehci-pci: probe of 0000:01:00.4 failed with error -12 > > This issue happens when the value of the sagaw corresponds to a > 48-bit agaw. This fix updates the calculation of the agaw based on > the minimum of IOMMU's sagaw value and MGAW. > > Cc: stable@xxxxxxxxxxxxxxx > Signed-off-by: Saeed Mirzamohammadi <saeed.mirzamohammadi@xxxxxxxxxx> > Tested-by: Camille Lu <camille.lu@xxxxxxx> > Reviewed-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx> > > --- Also when you resend this, please state the commit that this fixes, as this must be a regression, right? What kernel version did this previous work for? thanks, greg k-h
