On Thu, Jun 18, 2015 at 09:37:33PM +1000, Alexey Kardashevskiy wrote: > sPAPR IOMMU is managing two copies of an TCE table: > 1) a guest view of the table - this is what emulated devices use and > this is where H_GET_TCE reads from; > 2) a hardware TCE table - only present if there is at least one vfio-pci > device on a PHB; it is updated via a memory listener on a PHB address > space which forwards map/unmap requests to vfio-pci IOMMU host driver. > > At the moment presence of vfio-pci devices on a bus affect the way > the guest view table is allocated. If there is no vfio-pci on a PHB > and the host kernel supports KVM acceleration of H_PUT_TCE, a table > is allocated in KVM. However, if there is vfio-pci and we do yet not > support KVM acceleration for these, the table has to be allocated > by the userspace. > > When vfio-pci device is hotplugged and there were no vfio-pci devices > already, the guest view table could have been allocated by KVM which > means that H_PUT_TCE is handled by the host kernel and since we > do not support vfio-pci in KVM, the hardware table will not be updated. > > This reallocates the guest view table in QEMU if the first vfio-pci > device has just been plugged. spapr_tce_realloc_userspace() handles this. > > This replays all the mappings to make sure that the tables are in sync. > This will not have a visible effect though as for a new device > the guest kernel will allocate-and-map new addresses and therefore > existing mappings from emulated devices will not be used by vfio-pci > devices. > > This adds calls to spapr_phb_dma_capabilities_update() in PCI hotplug > hooks . > > Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru>
Reviewed-by: David Gibson <da...@gibson.dropbear.id.au>
Please ignore comment about hotplug I made on the previous patch, not
having read this one.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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