On Wed, Sep 28, 2022 at 10:58:22AM +0200, Niklas Schnelle wrote: > On Tue, 2022-09-27 at 13:56 -0300, Jason Gunthorpe wrote: > > On Tue, Sep 27, 2022 at 06:33:48PM +0200, Niklas Schnelle wrote: > > > > > Not sure what the non-MSI reservation is for? It does seem like x86_64 > > > also uses this for quite large ranges. > > > > There are lots of things that are unsuitable for DMA on x86 platforms, > > unfortunately.. But yeah, I'm not sure either. > > > > > This is because I'm getting a map request for an IOVA in the reserved > > > region. > > > > How come? iova_reserve_iommu_regions() reads the reserved regions and > > loads them as reserved into the iovad which should cause > > iommu_dma_alloc_iova() and alloc_iova_fast() to not return values in > > those ranges. > > > > It all looks like it is supposed to work > > > > Did something go wrong in the initialization order perhaps? > > > > Jason > > It was of course a classic off-by-one, the table size is a number of > entries but geometry.aperture_end seems to be the largest allowed IOVA. > So we need: Right, I dislike this naming usually 'end' means "start + length" and 'last' means "start + length - 1" > Otherwise the first IOVA allocated is ZPCI_TABLE_SIZE_RT itself. > Similarly we need the second reserved region if (zdev->end_dma < > ZPCI_TABLE_SIZE_RT - 1). In your patch I think you had the > MAX_DMA_TABLE_ADDR name right but would have also calculated the number > of entries. Make sense.. > On the other hand with the dma-iommu.c conversion it no longer makes > sense to lower zdev->end_dma artificially, so at least on current > machine LPARs we would end up with just a lower reserved region > 0x0000000000000000 to 0x00000000ffffffff and can use IOVAs up to > aperture_end. So zdev->end_dma == MAX_DMA_TABLE_ADDR? (and is zdev->end_dma and 'end' or 'last' ?) Can you include this patch once you are happy with it, it nicely tidies this series? Thanks, Jason
