netdev - [PATCH v14 12/22] sfc: obtain root decoder with enough HPA free space

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Message-ID: <20250417212926.1343268-13-alejandro.lucero-palau@amd.com>
Date: Thu, 17 Apr 2025 22:29:15 +0100
From: <alejandro.lucero-palau@....com>
To: <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>
CC: Alejandro Lucero <alucerop@....com>, Martin Habets
	<habetsm.xilinx@...il.com>, Edward Cree <ecree.xilinx@...il.com>, "Jonathan
 Cameron" <Jonathan.Cameron@...wei.com>
Subject: [PATCH v14 12/22] sfc: obtain root decoder with enough HPA free space

From: Alejandro Lucero <alucerop@....com>

Asking for available HPA space is the previous step to try to obtain
an HPA range suitable to accel driver purposes.

Add this call to efx cxl initialization.

Make sfc cxl build dependent on CXL region.

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>
---
 drivers/net/ethernet/sfc/Kconfig   |  1 +
 drivers/net/ethernet/sfc/efx_cxl.c | 19 +++++++++++++++++++
 2 files changed, 20 insertions(+)

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 04a65dd130a4..f08a9f43bd38 100644
--- a/drivers/net/ethernet/sfc/efx_cxl.c
+++ b/drivers/net/ethernet/sfc/efx_cxl.c
@@ -26,6 +26,7 @@ int efx_cxl_init(struct efx_probe_data *probe_data)
 	struct cxl_dpa_info sfc_dpa_info = {
 		.size = EFX_CTPIO_BUFFER_SIZE
 	};
+	resource_size_t max_size;
 	struct efx_cxl *cxl;
 	u16 dvsec;
 	int rc;
@@ -85,6 +86,22 @@ int efx_cxl_init(struct efx_probe_data *probe_data)
 		return PTR_ERR(cxl->cxlmd);
 	}
 
+	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");
+		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);
+		return -ENOSPC;
+	}
+
 	probe_data->cxl = cxl;
 
 	return 0;
@@ -92,6 +109,8 @@ int efx_cxl_init(struct efx_probe_data *probe_data)
 
 void efx_cxl_exit(struct efx_probe_data *probe_data)
 {
+	if (probe_data->cxl)
+		cxl_put_root_decoder(probe_data->cxl->cxlrd);
 }
 
 MODULE_IMPORT_NS("CXL");
-- 
2.34.1