Subject: Re: [PATCH 10/11] vfio: selftests: Add mlx5 driver - data path and memcpy ops

From: David Matlack <[email-masked]>
Date: Mon, 4 May 2026 22:41:08 +0000

On 2026-04-30 09:08 PM, Jason Gunthorpe wrote:

> @@ -1368,6 +1716,11 @@ static void mlx5st_init(struct vfio_pci_device *device)
>  	mlx5st_alloc_pd(dev);
>  	mlx5st_create_mkey(dev);
>  
> +	mlx5st_setup_datapath(dev);
> +
> +	device->driver.max_memcpy_size = 1 << 20;
> +	device->driver.max_memcpy_count = SQ_WQE_CNT - 1;

What are these limits a function of? e.g. Is the 1MB size a hardware
limit? Can we change SQ_WQE_CNT in the future to increase max count?

I'm interested in this because for Live Update testing we've found it
valuable to keep the device busy for several minutes so that it can do
DMA continuously throughout the Live Update.

> +
>  	dev_dbg(device, "mlx5 driver initialized\n");
>  }