Messages in this thread | | | Date | Thu, 27 Apr 2017 23:03:25 +0200 | From | Joerg Roedel <> | Subject | Re: [RFC PATCH 0/2] iommu/s390: Fix iommu-groups and add sysfs support |
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Hi Gerald,
thanks for your reply. I have some more questions, please see below.
On Thu, Apr 27, 2017 at 08:10:18PM +0200, Gerald Schaefer wrote:
> Well, there is a separate zpci_dev for each pci_dev on s390, > and each of those has its own separate dma-table (thus not shared).
Is that true for all functions of a PCIe card, so does every function of a device has its own zpci_dev structure and thus its own DMA-table?
My assumption came from the fact that the zpci_dev is read from pci_dev->sysdata, which is propagated there from the pci_bridge through the pci_root_bus structures.
> Given this "separate zpci_dev for each pci_dev" situation, I don't > see what this update actually changes, compared to the previous code, > see also my comments to that patch.
The add_device call-back is invoked for every function of a pci-device, because each function gets its own pci_dev structure. Also we usually group all functions of a PCI-device together into one iommu-group, because we don't trust that the device isolates its functions from each other.
Regards,
Joerg
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