ACK: [SRU][J/K][PATCH 0/1] Ice ethernet driver fails to alloc MSI-X on high cpu count systems

[Tim Gardner]

On 4/14/23 3:29 PM, Luke Nowakowski-Krijger wrote:
> BugLink: https://bugs.launchpad.net/bugs/2012335
> 
> SRU Justification:
> 
> [Impact]
> 
> There is a user reporting errors in setup with their Intel E810 NIC with
> error messages saying that the driver cannot allocate enough MSI-X vectors
> on their 256 cpu-count system.
> 
> It seems the ICE ethernet driver has an all or nothing approach to
> allocating MSI-X vectors and could request more MSI-X vectors than it
> finds available, which could lead to the driver failing to initialize and
> start.
> 
> [Fix]
> 
> The patch that fixes this allocates as many MSI-X vectors as it can to continue
> functionality by reducing the number of requested MSI-X vectors if it does
> not have enough to do full allocation.
> 
> [Backport]
> 
> In Jammy we do not carry patches for switchdev support in the driver so do not
> allocate the switchdev MSI-X vector for it. Also in Jammy use the older
> way of checking RDMA support by testing the RDMA bit is set as opposed to the newer
> ice_is_rdma_ena that the patch uses.
> 
> [Test Plan]
> 
> Install and startup Ice driver with an Intel 800 series NIC and check that we
> do not have the failure:
> 
> Not enough device MSI-X vectors, requested = 260, available = 253
> 
> and check that everything works as expected.
> 
> The backported patch for Jammy has been tested by the original user who
> submited the bug report with their high cpu count system and confirmed no errors.
> 
> [Where problems could occur]
> 
> There could be problems with the logic of reducing the MSI-X vector
> usage leading to more errors in the driver, but otherwise minimal
> regression potential as the code is mostly refactoring initial MSI-X
> setup.
> 
> 
> Tony Nguyen (1):
>    ice: Allow operation with reduced device MSI-X
> 
>   drivers/net/ethernet/intel/ice/ice_main.c | 185 ++++++++++++----------
>   1 file changed, 100 insertions(+), 85 deletions(-)
> 
Acked-by: Tim Gardner <tim.gardner at canonical.com>
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Tim Gardner
Canonical, Inc