netdev - Re: [PATCH v18 10/20] sfc: get root decoder

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Message-ID: <c4d4f61a-ef32-4156-a083-399b81a314e7@intel.com>
Date: Fri, 19 Sep 2025 11:20:54 -0700
From: Dave Jiang <dave.jiang@...el.com>
To: alejandro.lucero-palau@....com, 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
Cc: Alejandro Lucero <alucerop@....com>,
 Martin Habets <habetsm.xilinx@...il.com>,
 Edward Cree <ecree.xilinx@...il.com>,
 Jonathan Cameron <Jonathan.Cameron@...wei.com>
Subject: Re: [PATCH v18 10/20] sfc: get root decoder



On 9/18/25 2:17 AM, alejandro.lucero-palau@....com wrote:
> From: Alejandro Lucero <alucerop@....com>
> 
> Use cxl api for getting HPA (Host Physical Address) to use from a
> CXL root decoder.
> 
> Signed-off-by: Alejandro Lucero <alucerop@....com>
> Reviewed-by: Martin Habets <habetsm.xilinx@...il.com>
> Acked-by: Edward Cree <ecree.xilinx@...il.com>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>

Reviewed-by: Dave Jiang <dave.jiang@...el.com>
> ---
>  drivers/cxl/cxl.h                  | 15 ---------------
>  drivers/net/ethernet/sfc/Kconfig   |  1 +
>  drivers/net/ethernet/sfc/efx_cxl.c | 27 +++++++++++++++++++++++++++
>  include/cxl/cxl.h                  | 14 ++++++++++++++
>  4 files changed, 42 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
> index 076640e91ee0..ab490b5a9457 100644
> --- a/drivers/cxl/cxl.h
> +++ b/drivers/cxl/cxl.h
> @@ -219,21 +219,6 @@ int cxl_dport_map_rcd_linkcap(struct pci_dev *pdev, struct cxl_dport *dport);
>  #define CXL_RESOURCE_NONE ((resource_size_t) -1)
>  #define CXL_TARGET_STRLEN 20
>  
> -/*
> - * cxl_decoder flags that define the type of memory / devices this
> - * decoder supports as well as configuration lock status See "CXL 2.0
> - * 8.2.5.12.7 CXL HDM Decoder 0 Control Register" for details.
> - * Additionally indicate whether decoder settings were autodetected,
> - * user customized.
> - */
> -#define CXL_DECODER_F_RAM   BIT(0)
> -#define CXL_DECODER_F_PMEM  BIT(1)
> -#define CXL_DECODER_F_TYPE2 BIT(2)
> -#define CXL_DECODER_F_TYPE3 BIT(3)
> -#define CXL_DECODER_F_LOCK  BIT(4)
> -#define CXL_DECODER_F_ENABLE    BIT(5)
> -#define CXL_DECODER_F_MASK  GENMASK(5, 0)
> -
>  enum cxl_decoder_type {
>  	CXL_DECODER_DEVMEM = 2,
>  	CXL_DECODER_HOSTONLYMEM = 3,
> diff --git a/drivers/net/ethernet/sfc/Kconfig b/drivers/net/ethernet/sfc/Kconfig
> index 979f2801e2a8..e959d9b4f4ce 100644
> --- a/drivers/net/ethernet/sfc/Kconfig
> +++ b/drivers/net/ethernet/sfc/Kconfig
> @@ -69,6 +69,7 @@ config SFC_MCDI_LOGGING
>  config SFC_CXL
>  	bool "Solarflare SFC9100-family CXL support"
>  	depends on SFC && CXL_BUS >= SFC
> +	depends on CXL_REGION
>  	default SFC
>  	help
>  	  This enables SFC CXL support if the kernel is configuring CXL for
> diff --git a/drivers/net/ethernet/sfc/efx_cxl.c b/drivers/net/ethernet/sfc/efx_cxl.c
> index 177c60b269d6..d29594e71027 100644
> --- a/drivers/net/ethernet/sfc/efx_cxl.c
> +++ b/drivers/net/ethernet/sfc/efx_cxl.c
> @@ -18,6 +18,7 @@ int efx_cxl_init(struct efx_probe_data *probe_data)
>  {
>  	struct efx_nic *efx = &probe_data->efx;
>  	struct pci_dev *pci_dev = efx->pci_dev;
> +	resource_size_t max_size;
>  	struct efx_cxl *cxl;
>  	u16 dvsec;
>  	int rc;
> @@ -88,13 +89,39 @@ int efx_cxl_init(struct efx_probe_data *probe_data)
>  		return PTR_ERR(cxl->cxlmd);
>  	}
>  
> +	cxl->endpoint = cxl_acquire_endpoint(cxl->cxlmd);
> +	if (IS_ERR(cxl->endpoint))
> +		return PTR_ERR(cxl->endpoint);
> +
> +	cxl->cxlrd = cxl_get_hpa_freespace(cxl->cxlmd, 1,
> +					   CXL_DECODER_F_RAM | CXL_DECODER_F_TYPE2,
> +					   &max_size);
> +
> +	if (IS_ERR(cxl->cxlrd)) {
> +		pci_err(pci_dev, "cxl_get_hpa_freespace failed\n");
> +		cxl_release_endpoint(cxl->cxlmd, cxl->endpoint);
> +		return PTR_ERR(cxl->cxlrd);
> +	}
> +
> +	if (max_size < EFX_CTPIO_BUFFER_SIZE) {
> +		pci_err(pci_dev, "%s: not enough free HPA space %pap < %u\n",
> +			__func__, &max_size, EFX_CTPIO_BUFFER_SIZE);
> +		cxl_put_root_decoder(cxl->cxlrd);
> +		cxl_release_endpoint(cxl->cxlmd, cxl->endpoint);
> +		return -ENOSPC;
> +	}
> +
>  	probe_data->cxl = cxl;
>  
> +	cxl_release_endpoint(cxl->cxlmd, cxl->endpoint);
> +
>  	return 0;
>  }
>  
>  void efx_cxl_exit(struct efx_probe_data *probe_data)
>  {
> +	if (probe_data->cxl)
> +		cxl_put_root_decoder(probe_data->cxl->cxlrd);
>  }
>  
>  MODULE_IMPORT_NS("CXL");
> diff --git a/include/cxl/cxl.h b/include/cxl/cxl.h
> index 7722d4190573..788700fb1eb2 100644
> --- a/include/cxl/cxl.h
> +++ b/include/cxl/cxl.h
> @@ -153,6 +153,20 @@ struct cxl_dpa_partition {
>  
>  #define CXL_NR_PARTITIONS_MAX 2
>  
> +/*
> + * cxl_decoder flags that define the type of memory / devices this
> + * decoder supports as well as configuration lock status See "CXL 2.0
> + * 8.2.5.12.7 CXL HDM Decoder 0 Control Register" for details.
> + * Additionally indicate whether decoder settings were autodetected,
> + * user customized.
> + */
> +#define CXL_DECODER_F_RAM   BIT(0)
> +#define CXL_DECODER_F_PMEM  BIT(1)
> +#define CXL_DECODER_F_TYPE2 BIT(2)
> +#define CXL_DECODER_F_TYPE3 BIT(3)
> +#define CXL_DECODER_F_LOCK  BIT(4)
> +#define CXL_DECODER_F_ENABLE    BIT(5)
> +
>  struct cxl_memdev_ops {
>  	int (*probe)(struct cxl_memdev *cxlmd);
>  };