On 08/11/2013 11:58 PM, Michael S. Tsirkin wrote:
> On Sat, Aug 10, 2013 at 01:09:08AM +1000, Alexey Kardashevskiy wrote:
>> A PCI device's DMA address space (possibly an IOMMU) is returned by a
>> method on the PCIBus. At the moment that only has one caller, so the
>> method is simply open coded. We'll need another caller for VFIO, so
>> this patch introduces a helper/wrapper function.
>>
>> If IOMMU is not set, the pci_device_iommu_address_space() function
>> returns the parent's IOMMU skipping the "bus master" address space as
>> otherwise proper emulation would require more effort for no benefit.
>>
>> Signed-off-by: David Gibson <da...@gibson.dropbear.id.au>
>> [aik: added inheritance from parent if iommu is not set for the current bus]
>> Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru>
>>
>> ---
>> Changes:
>> v3:
>> * added comment about ignoring bus master address space
>>
>> v2:
>> * added inheritance, needed for a pci-bridge on spapr-ppc64
>> * pci_iommu_as renamed to pci_device_iommu_address_space
>> ---
>> hw/pci/pci.c | 24 ++++++++++++++++++------
>> include/hw/pci/pci.h | 1 +
>> 2 files changed, 19 insertions(+), 6 deletions(-)
>>
>> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
>> index 4c004f5..dbfa395 100644
>> --- a/hw/pci/pci.c
>> +++ b/hw/pci/pci.c
>> @@ -812,12 +812,7 @@ static PCIDevice *do_pci_register_device(PCIDevice
>> *pci_dev, PCIBus *bus,
>> }
>>
>> pci_dev->bus = bus;
>> - if (bus->iommu_fn) {
>> - dma_as = bus->iommu_fn(bus, bus->iommu_opaque, devfn);
>> - } else {
>> - /* FIXME: inherit memory region from bus creator */
>> - dma_as = &address_space_memory;
>> - }
>> + dma_as = pci_device_iommu_address_space(pci_dev);
>>
>> memory_region_init_alias(&pci_dev->bus_master_enable_region,
>> OBJECT(pci_dev), "bus master",
>> @@ -2239,6 +2234,23 @@ static void pci_device_class_init(ObjectClass *klass,
>> void *data)
>> k->props = pci_props;
>> }
>>
>> +AddressSpace *pci_device_iommu_address_space(PCIDevice *dev)
>> +{
>> + PCIBus *bus = PCI_BUS(dev->bus);
>> +
>> + if (bus->iommu_fn) {
>> + return bus->iommu_fn(bus, bus->iommu_opaque, dev->devfn);
>> + }
>> +
>> + if (bus->parent_dev) {
>> + /** We are ignoring the bus master DMA bit of the bridge
>> + * as it would complicate things such as VFIO for no good reason */
>
> /*
> * Always
> * like
> * this
> */
>
> /** Never
> * like this */
Hm. I thought I saw a lot of those but it was the kernel :)
btw may comments start with "/**" (with no text in that line but still) -
what is the difference to "/*"?
> The comment should be improved I think.
> I would put it like this:
> /*
> * Note: this does not check bus master enable bit on device or
> * any of the pci to pci bridges above it, it's up to the caller to
> * check that before initiating the transaction.
> *
> * TODO: design a mechanism for callers to do this without
> * doing bus scans on data path.
> */
What exactly do you call here "bus scans"?
> Would you like me to queue this on the pci tree? If yes I can
> tweak the comment myself, no need to repost.
Yes, please. Your tree is fine. Thanks!
>> + return pci_device_iommu_address_space(bus->parent_dev);
>> + }
>> +
>> + return &address_space_memory;
>> +}
>> +
>> void pci_setup_iommu(PCIBus *bus, PCIIOMMUFunc fn, void *opaque)
>> {
>> bus->iommu_fn = fn;
>> diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h
>> index ccec2ba..2374aa9 100644
>> --- a/include/hw/pci/pci.h
>> +++ b/include/hw/pci/pci.h
>> @@ -405,6 +405,7 @@ void pci_device_deassert_intx(PCIDevice *dev);
>>
>> typedef AddressSpace *(*PCIIOMMUFunc)(PCIBus *, void *, int);
>>
>> +AddressSpace *pci_device_iommu_address_space(PCIDevice *dev);
>> void pci_setup_iommu(PCIBus *bus, PCIIOMMUFunc fn, void *opaque);
>>
>> static inline void
--
Alexey
