On 27.10.2015 [16:56:10 +1100], Alexey Kardashevskiy wrote:
> On 10/24/2015 07:59 AM, Nishanth Aravamudan wrote:
> >When DDW (Dynamic DMA Windows) are present for a device, we have stored
> >the TCE (Translation Control Entry) size in a special device tree
> >property. Check if we have enabled DDW for the device and return the TCE
> >size from that property if present. If the property isn't present,
> >fallback to looking the value up in struct iommu_table. If we don't find
> >a iommu_table, fallback to the kernel's page size.
> >
> >Signed-off-by: Nishanth Aravamudan <n...@linux.vnet.ibm.com>
> >---
> > arch/powerpc/platforms/pseries/iommu.c | 36
> > ++++++++++++++++++++++++++++++++++
> > 1 file changed, 36 insertions(+)
> >
> >diff --git a/arch/powerpc/platforms/pseries/iommu.c
> >b/arch/powerpc/platforms/pseries/iommu.c
> >index 0946b98..1bf6471 100644
> >--- a/arch/powerpc/platforms/pseries/iommu.c
> >+++ b/arch/powerpc/platforms/pseries/iommu.c
> >@@ -1292,6 +1292,40 @@ static u64 dma_get_required_mask_pSeriesLP(struct
> >device *dev)
> > return dma_iommu_ops.get_required_mask(dev);
> > }
> >
> >+static unsigned long dma_get_page_shift_pSeriesLP(struct device *dev)
> >+{
> >+ struct iommu_table *tbl;
> >+
> >+ if (!disable_ddw && dev_is_pci(dev)) {
> >+ struct pci_dev *pdev = to_pci_dev(dev);
> >+ struct device_node *dn;
> >+
> >+ dn = pci_device_to_OF_node(pdev);
> >+
> >+ /* search upwards for ibm,dma-window */
> >+ for (; dn && PCI_DN(dn) && !PCI_DN(dn)->table_group;
> >+ dn = dn->parent)
> >+ if (of_get_property(dn, "ibm,dma-window", NULL))
> >+ break;
> >+ /*
> >+ * if there is a DDW configuration, the TCE shift is stored in
> >+ * the property
> >+ */
> >+ if (dn && PCI_DN(dn)) {
> >+ const struct dynamic_dma_window_prop *direct64 =
> >+ of_get_property(dn, DIRECT64_PROPNAME, NULL);
>
>
> This DIRECT64_PROPNAME property is only present under pHyp, QEMU/KVM
> does not set it as 64bit windows are dynamic there so something like
> find_existing_ddw() needs to be used here.
DIRECT64_PROPNAME is a Linux thing, not a pHyp or QEMU/KVM thing -- it's
created by the Linux DDW logic and left in the device-tree when we
successfully configure DDW.
You're right, though, that logically find_existing_ddw() would be better
to use here. I'll spin up a new version.
-Nish
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