From: Ankit Agrawal <ankita@nvidia.com>

NVIDIA's recently introduced Grace Blackwell (GB) Superchip in
continuation with the Grace Hopper (GH) superchip that provides a
cache coherent access to CPU and GPU to each other's memory with
an internal proprietary chip-to-chip (C2C) cache coherent interconnect.
The in-tree nvgrace-gpu driver manages the GH devices. The intention
is to extend the support to the new Grace Blackwell boards.

There is a HW defect on GH to support the Multi-Instance GPU (MIG)
feature [1] that necessiated the presence of a 1G carved out from
the device memory and mapped uncached. The 1G region is shown as a
fake BAR (comprising region 2 and 3) to workaround the issue.

The GB systems differ from GH systems in the following aspects.
1. The aforementioned HW defect is fixed on GB systems.
2. There is a usable BAR1 (region 2 and 3) on GB systems for the
GPUdirect RDMA feature [2].

This patch series accommodate those GB changes by showing the real
physical device BAR1 (region2 and 3) to the VM instead of the fake
one. This takes care of both the differences.

The presence of the fix for the HW defect is communicated by the
firmware through a DVSEC PCI config register. The module reads
this to take a different codepath on GB vs GH.

To improve system bootup time, HBM training is moved out of UEFI
in GB system. Poll for the register indicating the training state.
Also check the C2C link status if it is ready. Fail the probe if
either fails.

Link: https://www.nvidia.com/en-in/technologies/multi-instance-gpu/ [1]
Link: https://docs.nvidia.com/cuda/gpudirect-rdma/ [2]

Applied over next-20241003.

Signed-off-by: Ankit Agrawal <ankita@nvidia.com>

Ankit Agrawal (3):
  vfio/nvgrace-gpu: Read dvsec register to determine need for uncached
    resmem
  vfio/nvgrace-gpu: Expose the blackwell device PF BAR1 to the VM
  vfio/nvgrace-gpu: Check the HBM training and C2C link status

 drivers/vfio/pci/nvgrace-gpu/main.c | 115 ++++++++++++++++++++++++++--
 1 file changed, 107 insertions(+), 8 deletions(-)

-- 
2.34.1

On Sun, 6 Oct 2024 10:27:19 +0000
<ankita@nvidia.com> wrote:

> From: Ankit Agrawal <ankita@nvidia.com>
> 
> NVIDIA's recently introduced Grace Blackwell (GB) Superchip in
> continuation with the Grace Hopper (GH) superchip that provides a
> cache coherent access to CPU and GPU to each other's memory with
> an internal proprietary chip-to-chip (C2C) cache coherent interconnect.
> The in-tree nvgrace-gpu driver manages the GH devices. The intention
> is to extend the support to the new Grace Blackwell boards.

Where do we stand on QEMU enablement of GH, or the GB support here?
IIRC, the nvgrace-gpu variant driver was initially proposed with QEMU
being the means through which the community could make use of this
driver, but there seem to be a number of pieces missing for that
support.  Thanks,

Alex

> There is a HW defect on GH to support the Multi-Instance GPU (MIG)
> feature [1] that necessiated the presence of a 1G carved out from
> the device memory and mapped uncached. The 1G region is shown as a
> fake BAR (comprising region 2 and 3) to workaround the issue.
> 
> The GB systems differ from GH systems in the following aspects.
> 1. The aforementioned HW defect is fixed on GB systems.
> 2. There is a usable BAR1 (region 2 and 3) on GB systems for the
> GPUdirect RDMA feature [2].
> 
> This patch series accommodate those GB changes by showing the real
> physical device BAR1 (region2 and 3) to the VM instead of the fake
> one. This takes care of both the differences.
> 
> The presence of the fix for the HW defect is communicated by the
> firmware through a DVSEC PCI config register. The module reads
> this to take a different codepath on GB vs GH.
> 
> To improve system bootup time, HBM training is moved out of UEFI
> in GB system. Poll for the register indicating the training state.
> Also check the C2C link status if it is ready. Fail the probe if
> either fails.
> 
> Link: https://www.nvidia.com/en-in/technologies/multi-instance-gpu/ [1]
> Link: https://docs.nvidia.com/cuda/gpudirect-rdma/ [2]
> 
> Applied over next-20241003.
> 
> Signed-off-by: Ankit Agrawal <ankita@nvidia.com>
> 
> Ankit Agrawal (3):
>   vfio/nvgrace-gpu: Read dvsec register to determine need for uncached
>     resmem
>   vfio/nvgrace-gpu: Expose the blackwell device PF BAR1 to the VM
>   vfio/nvgrace-gpu: Check the HBM training and C2C link status
> 
>  drivers/vfio/pci/nvgrace-gpu/main.c | 115 ++++++++++++++++++++++++++--
>  1 file changed, 107 insertions(+), 8 deletions(-)
>