netdev - Re: [PATCH v17 20/22] sfc: create cxl region

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Message-ID: <20250627103828.000000c7@huawei.com>
Date: Fri, 27 Jun 2025 10:38:28 +0100
From: Jonathan Cameron <Jonathan.Cameron@...wei.com>
To: <alejandro.lucero-palau@....com>
CC: <linux-cxl@...r.kernel.org>, <netdev@...r.kernel.org>,
	<dan.j.williams@...el.com>, <edward.cree@....com>, <davem@...emloft.net>,
	<kuba@...nel.org>, <pabeni@...hat.com>, <edumazet@...gle.com>,
	<dave.jiang@...el.com>, Alejandro Lucero <alucerop@....com>
Subject: Re: [PATCH v17 20/22] sfc: create cxl region

On Tue, 24 Jun 2025 15:13:53 +0100
<alejandro.lucero-palau@....com> wrote:

> From: Alejandro Lucero <alucerop@....com>
> 
> Use cxl api for creating a region using the endpoint decoder related to
> a DPA range.
> 
> Add a callback for unwinding sfc cxl initialization when the endpoint port
> is destroyed by potential cxl_acpi or cxl_mem modules removal.
> 
> Signed-off-by: Alejandro Lucero <alucerop@....com>
> ---
>  drivers/net/ethernet/sfc/efx_cxl.c | 24 +++++++++++++++++++++++-
>  1 file changed, 23 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/sfc/efx_cxl.c b/drivers/net/ethernet/sfc/efx_cxl.c
> index ffbf0e706330..7365effe974e 100644
> --- a/drivers/net/ethernet/sfc/efx_cxl.c
> +++ b/drivers/net/ethernet/sfc/efx_cxl.c
> @@ -18,6 +18,16 @@
>  
>  #define EFX_CTPIO_BUFFER_SIZE	SZ_256M
>  
> +static void efx_release_cxl_region(void *priv_cxl)
> +{
> +	struct efx_probe_data *probe_data = priv_cxl;
> +	struct efx_cxl *cxl = probe_data->cxl;
> +
> +	iounmap(cxl->ctpio_cxl);
> +	cxl_put_root_decoder(cxl->cxlrd);
> +	probe_data->cxl_pio_initialised = false;
> +}
> +
>  int efx_cxl_init(struct efx_probe_data *probe_data)
>  {
>  	struct efx_nic *efx = &probe_data->efx;
> @@ -116,10 +126,21 @@ int efx_cxl_init(struct efx_probe_data *probe_data)
>  		goto put_root_decoder;
>  	}
>  
> +	cxl->efx_region = cxl_create_region(cxl->cxlrd, &cxl->cxled, 1,
> +					    efx_release_cxl_region,

As per earlier comment - given when it's released, I'd register the devm callback
out here not in cxl_create_region(). Might irritate the net maintainers though
as it would be a devm callback registered in non CXL code, but I don't think
that is a reason to jump through the hoops you currently have.


> +					    &probe_data);
> +	if (IS_ERR(cxl->efx_region)) {
> +		pci_err(pci_dev, "CXL accel create region failed");
> +		rc = PTR_ERR(cxl->efx_region);
> +		goto err_region;
> +	}
> +
>  	probe_data->cxl = cxl;
>  
>  	goto endpoint_release;
>  
> +err_region:
> +	cxl_dpa_free(cxl->cxled);
>  put_root_decoder:
>  	cxl_put_root_decoder(cxl->cxlrd);
>  endpoint_release:
> @@ -129,7 +150,8 @@ int efx_cxl_init(struct efx_probe_data *probe_data)
>  
>  void efx_cxl_exit(struct efx_probe_data *probe_data)
>  {
> -	if (probe_data->cxl) {
> +	if (probe_data->cxl_pio_initialised) {

Doesn't make sense yet because it's never true yet.  I assume the code
doesn't always fail in a way it didn't until now?

> +		cxl_decoder_kill_region(probe_data->cxl->cxled);
>  		cxl_dpa_free(probe_data->cxl->cxled);
>  		cxl_put_root_decoder(probe_data->cxl->cxlrd);
>  	}