Re: [PATCH v3 07/23] OvmfPkg/Virtio: take RingBaseShift in SetQueueAddress()

[Laszlo Ersek <lersek@redhat.com>]

On 08/23/17 22:41, Laszlo Ersek wrote:
> On 08/23/17 14:22, Brijesh Singh wrote:
>> For the case when an IOMMU is used for translating system physical
>> addresses to DMA bus master addresses, the transport-independent
>> virtio device drivers will be required to map their VRING areas to
>> bus addresses with VIRTIO_DEVICE_PROTOCOL.MapSharedBuffer() calls.
>>
>> VirtioRingMap() maps the ring buffer system physical to a bus address.
>> When an IOMMU is used for translating the address then bus address can
>> start at a different offset from the system physical address.
> 
> (1) The paragraph that you now have as first paragraph above was my
> suggestion, so thank you for picking it up. However, the second
> paragraph should have been deleted; I suggested the now-first paragraph
> as a replacement for the now-second one.
> 
> I wrote, "to keep our references within the virtio device protocol".
> VirtioRingMap() is a VirtioLib function, which is a utility layer on top
> of the virtio device protocol. So, as I said, VirtioLib patches may
> refer to both VirtioLib and the protocol, but protocol patches should
> preferably only refer to the protocol, and not VirtioLib.
> 
>   VirtioLib --+
>    |  ^       |
>    |  |       |
>    |  +-------+
>    |
>    v
>   VirtioDeviceProtocol --+
>                 ^        |
>                 |        |
>                 +--------+
> 
> This is also consistent with the reordering of the patches that I asked
> for (and that you implemented well in v3, thank you for it).
> 
> So, apologies if I wasn't clear enough of this -- it's not a big deal at
> all, I can remove the second paragraph when I push this.
> 
> Reviewed-by: Laszlo Ersek <lersek@redhat.com>
> 
> Thanks!
> Laszlo
> 
>>
>> - MMIO and legacy virtio transport do not support IOMMU to translate the
>>   addresses hence RingBaseShift will always be set to zero.
>>
>> - modern virtio transport supports IOMMU to translate the address, in
>>   next patch we will update the Virtio10Dxe to use RingBaseShift offset.
>>
>> Suggested-by: Laszlo Ersek <lersek@redhat.com>
>> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
>> Cc: Jordan Justen <jordan.l.justen@intel.com>
>> Cc: Tom Lendacky <thomas.lendacky@amd.com>
>> Cc: Laszlo Ersek <lersek@redhat.com>
>> Contributed-under: TianoCore Contribution Agreement 1.1
>> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
>> ---
>>  OvmfPkg/Include/Protocol/VirtioDevice.h                         | 19 +++++++++++++++++--
>>  OvmfPkg/Library/VirtioMmioDeviceLib/VirtioMmioDevice.h          |  3 ++-
>>  OvmfPkg/VirtioPciDeviceDxe/VirtioPciDevice.h                    |  3 ++-
>>  OvmfPkg/Library/VirtioMmioDeviceLib/VirtioMmioDeviceFunctions.c |  5 ++++-
>>  OvmfPkg/Virtio10Dxe/Virtio10.c                                  |  5 ++++-
>>  OvmfPkg/VirtioBlkDxe/VirtioBlk.c                                |  2 +-
>>  OvmfPkg/VirtioGpuDxe/Commands.c                                 |  6 +++++-
>>  OvmfPkg/VirtioNetDxe/SnpInitialize.c                            |  2 +-
>>  OvmfPkg/VirtioPciDeviceDxe/VirtioPciFunctions.c                 |  5 ++++-
>>  OvmfPkg/VirtioRngDxe/VirtioRng.c                                |  2 +-
>>  OvmfPkg/VirtioScsiDxe/VirtioScsi.c                              |  2 +-
>>  11 files changed, 42 insertions(+), 12 deletions(-)
>>
>> diff --git a/OvmfPkg/Include/Protocol/VirtioDevice.h b/OvmfPkg/Include/Protocol/VirtioDevice.h
>> index 9a01932958a2..2e3a6d6edf04 100644
>> --- a/OvmfPkg/Include/Protocol/VirtioDevice.h
>> +++ b/OvmfPkg/Include/Protocol/VirtioDevice.h
>> @@ -156,7 +156,21 @@ EFI_STATUS
>>    @param[in] This             This instance of VIRTIO_DEVICE_PROTOCOL
>>  
>>    @param[in] Ring             The initialized VRING object to take the
>> -                              addresses from.
>> +                              addresses from. The caller is responsible for
>> +                              ensuring that on input, all Ring->NumPages pages,
>> +                              starting at Ring->Base, have been successfully
>> +                              mapped with a single call to
>> +                              This->MapSharedBuffer() for CommonBuffer bus
>> +                              master operation..

(2) I'll also remove one of the periods.

Thanks
Laszlo