On 09/05/17 14:41, Laszlo Ersek wrote: > On 09/01/17 13:24, Brijesh Singh wrote: >> When device is behind the IOMMU, driver is require to pass the device >> address of transmit buffer for the bus master operations. >> >> The patch uses VirtioMapAllBytesInSharedBuffer() to map transmit buffer >> system physical address to the device address. >> >> Since the transmit buffers are returned back to caller in >> VirtioNetGetStatus() hence we use OrderCollection library interface to >> save the host to device address mapping. After the buffer is succesfully >> transmited we do reverse lookup in OrderCollection data structure to get >> the host address for the transmitted device address. >> >> Cc: Ard Biesheuvel <[email protected]> >> Cc: Jordan Justen <[email protected]> >> Cc: Tom Lendacky <[email protected]> >> Cc: Laszlo Ersek <[email protected]> >> Contributed-under: TianoCore Contribution Agreement 1.1 >> Signed-off-by: Brijesh Singh <[email protected]> >> --- >> OvmfPkg/VirtioNetDxe/VirtioNet.inf | 1 + >> OvmfPkg/VirtioNetDxe/VirtioNet.h | 19 +++ >> OvmfPkg/VirtioNetDxe/SnpGetStatus.c | 30 +++- >> OvmfPkg/VirtioNetDxe/SnpSharedHelpers.c | 157 ++++++++++++++++++++ >> OvmfPkg/VirtioNetDxe/SnpTransmit.c | 37 ++++- >> 5 files changed, 232 insertions(+), 12 deletions(-)
> (7) We'll have to document the new model in "TechNotes.txt". I've now re-read the final section of the text file, section Virtio internals -- Tx I propose the following updates. (Here I'm providing a diff, not a desired "end status", like I did for the diagram earlier. A diff is harder to interpret for a diagram, but easy for plain text.) Please verify that the proposed documentation updates match the logic that you've implemented: > diff --git a/OvmfPkg/VirtioNetDxe/TechNotes.txt > b/OvmfPkg/VirtioNetDxe/TechNotes.txt > index 9c1dfe6a773e..7a7b3071abba 100644 > --- a/OvmfPkg/VirtioNetDxe/TechNotes.txt > +++ b/OvmfPkg/VirtioNetDxe/TechNotes.txt > @@ -310,10 +310,14 @@ in the following: > that is shared by all of the head descriptors. This virtio-net request > header > is never modified by the host. > > -- Each tail descriptor is re-pointed to the caller-supplied packet buffer > - whenever VirtioNetTransmit places the corresponding head descriptor on the > - Available Ring. The caller is responsible to hang on to the unmodified > buffer > - until it is reported transmitted by VirtioNetGetStatus. > +- Each tail descriptor is re-pointed to the device-mapped address of the > + caller-supplied packet buffer whenever VirtioNetTransmit places the > + corresponding head descriptor on the Available Ring. A reverse mapping, > from > + the device-mapped address to the caller-supplied packet address, is saved > in > + an associative data structure that belongs to the driver instance. > + > +- Per spec, the caller is responsible to hang on to the unmodified packet > + buffer until it is reported transmitted by VirtioNetGetStatus. > > Steps of packet transmission: > > @@ -336,9 +340,11 @@ Steps of packet transmission: > - Client code calls VirtioNetGetStatus. In case the Used Ring is empty, the > function reports no Tx completion. Otherwise, a head descriptor's index is > consumed from the Used Ring and recycled to the private stack. The client > - code's original packet buffer address is fetched from the tail descriptor > - (where it has been stored at VirtioNetTransmit time) and returned to the > - caller. > + code's original packet buffer address is calculated by fetching the > + device-mapped address from the tail descriptor (where it has been stored at > + VirtioNetTransmit time), and by looking up the device-mapped address in the > + associative data structure. The reverse-mapped packet buffer address is > + returned to the caller. > > - The Len field of the Used Ring Element is not checked. The host is assumed > to > have transmitted the entire packet -- VirtioNetTransmit had forced it below Thanks! Laszlo _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
