Re: [Qemu-devel] [PATCH 1/3] msi/msix: added functions to API to set up message address and data

[Alexey Kardashevskiy <aik@ozlabs.ru>]

On 14/06/12 15:38, Alex Williamson wrote:
> On Thu, 2012-06-14 at 15:17 +1000, Alexey Kardashevskiy wrote:
>> On 14/06/12 14:56, Alex Williamson wrote:
>>> On Thu, 2012-06-14 at 14:31 +1000, Alexey Kardashevskiy wrote:
>>>> Normally QEMU expects the guest to initialize MSI/MSIX vectors.
>>>> However on POWER the guest uses RTAS subsystem to configure MSI/MSIX and
>>>> does not write these vectors to device's config space or MSIX BAR.
>>>>
>>>> On the other hand, msi_notify()/msix_notify() write to these vectors to
>>>> signal the guest about an interrupt so we have to write correct vectors
>>>> to the devices in order not to change every user of MSI/MSIX.
>>>>
>>>> The first aim is to support MSIX for virtio-pci on POWER. There is
>>>> another patch for POWER coming which introduces a special memory region
>>>> where MSI/MSIX vectors point to.
>>>>
>>>> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
>>>> ---
>>>>  hw/msi.c  |   14 ++++++++++++++
>>>>  hw/msi.h  |    1 +
>>>>  hw/msix.c |   10 ++++++++++
>>>>  hw/msix.h |    3 +++
>>>>  4 files changed, 28 insertions(+), 0 deletions(-)
>>>>
>>>> diff --git a/hw/msi.c b/hw/msi.c
>>>> index 5d6ceb6..124878a 100644
>>>> --- a/hw/msi.c
>>>> +++ b/hw/msi.c
>>>> @@ -358,3 +358,17 @@ unsigned int msi_nr_vectors_allocated(const PCIDevice *dev)
>>>>      uint16_t flags = pci_get_word(dev->config + msi_flags_off(dev));
>>>>      return msi_nr_vectors(flags);
>>>>  }
>>>> +
>>>> +void msi_set_address_data(PCIDevice *dev, uint64_t address, uint16_t data)
>>>> +{
>>>> +    uint16_t flags = pci_get_word(dev->config + msi_flags_off(dev));
>>>> +    bool msi64bit = flags & PCI_MSI_FLAGS_64BIT;
>>>> +
>>>> +    if (msi64bit) {
>>>> +        pci_set_quad(dev->config + msi_address_lo_off(dev), address);
>>>> +    } else {
>>>> +        pci_set_long(dev->config + msi_address_lo_off(dev), address);
>>>> +    }
>>>> +    pci_set_word(dev->config + msi_data_off(dev, msi64bit), data);
>>>> +}
>>>
>>> Why not make it msi_set_message() and pass MSIMessage?  I'd be great if
>>> you tossed in a msi_get_message() as well, I think we need it to be able
>>> to do a kvm_irqchip_add_msi_route() with MSI.  Thanks,
>>
>>
>> I am missing the point. What is that MSIMessage?
>> It is just an address and data, making a struct from this is a bit too much :)
>> I am totally unfamiliar with kvm_irqchip_add_msi_route to see the bigger picture, sorry.
> 
> MSIVectorUseNotifier passes a MSIMessage back to the device when a
> vector is unmasked.  We can then add a route in KVM for that message
> with kvm_irqchip_add_msi_route.  Finally, kvm_irqchip_add_irqfd allows
> us to connect that MSI route to an eventfd, such as from virtio or vfio.
> Then MSI eventfds can bypass qemu and be injected directly into KVM and
> on into the guest.  So we seem to already have some standardization on
> passing address/data via an MSIMessage.
> 
> You need a "set" interface, I need a "get" interface.  msix already has
> a static msix_get_message().  So I'd suggest that an exported
> get/set_message for each seems like the right way to go.  Thanks,

Ok. Slowly :) What QEMU tree are you talking about? git, branch?
There is neither MSIVectorUseNotifier nor MSIMessage in your or mine trees.


-- 
Alexey