Some versions of the ENA firmware (observed on a c6i.large instance in
eu-west-2) will complain if the completion queue's MSI-X vector field
is left empty, even though the queue configuration specifies that
interrupts are not used.
Work around these firmware versions by passing in what appears to be
the magic "no MSI-X vector" value in this field.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The ENA data path design has separate submission and completion
queues. Submission queues must be refilled in strict order (since
there is only a single linear tail pointer used to communicate the
existence of new entries to the hardware), and completion queue
entries include a request identifier copied verbatim from the
submission queue entry. Once the submission queue doorbell has been
rung, software never again reads from the submission queue entry and
nothing ever needs to write back to the submission queue entry since
completions are reported via the separate completion queue.
This design allows the hardware to complete submission queue entries
out of order, provided that it internally caches at least as many
entries as it leaves gaps.
Record and identify I/O buffers by request identifier (using a
circular ring buffer of unique request identifiers), and remove the
assumption that submission queue entries will be completed in order.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The CREATE_CQ command is permitted to return a size smaller than
requested, which could leave us in a situation where the completion
queue could overflow.
Avoid overflow by limiting the submission queue fill level to the
actual size of the completion queue.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The Linux and FreeBSD drivers for the (totally undocumented) ENA
adapters use a two-phase reset mechanism: first set ENA_CTRL.RESET and
wait for this to be reflected in ENA_STAT.RESET, then clear
ENA_CTRL.RESET and again wait for it to be reflected in
ENA_STAT.RESET.
The iPXE driver currently assumes a self-clearing reset mechanism,
which appeared to work at the time that the driver was created but
seems no longer to function, at least on the t3.nano and t3a.nano
instance types found in eu-west-1.
Switch to a simplified version of the two-phase reset mechanism as
used by Linux and FreeBSD.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The malloc_dma() function allocates memory with specified physical
alignment, and is typically (though not exclusively) used to allocate
memory for DMA.
Rename to malloc_phys() to more closely match the functionality, and
to create name space for functions that specifically allocate and map
DMA-capable buffers.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Devices that support jumbo frames will currently default to the
largest possible MTU. This assumption is valid for virtual adapters
such as virtio-net, where the MTU must have been configured by a
system administrator, but is unsafe in the general case of a physical
adapter.
Default to the standard Ethernet MTU, unless explicitly overridden
either by the driver or via the ${netX/mtu} setting.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Some older versions of gcc (observed with gcc 4.7.2) report a spurious
uninitialised variable warning in ena_get_device_attributes(). Work
around this warning by manually inlining the relevant code (which has
only a single call site).
Reported-by: xbgmsharp <xbgmsharp@gmail.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
