netdev - [PATCH v12 12/23] sfc: obtain root decoder with enough HPA free space

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Message-ID: <20250331144555.1947819-13-alejandro.lucero-palau@amd.com>
Date: Mon, 31 Mar 2025 15:45:44 +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 v12 12/23] 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 | 21 +++++++++++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/drivers/net/ethernet/sfc/Kconfig b/drivers/net/ethernet/sfc/Kconfig
index c5fb71e601e7..7a23d6d6d85f 100644
--- a/drivers/net/ethernet/sfc/Kconfig
+++ b/drivers/net/ethernet/sfc/Kconfig
@@ -68,6 +68,7 @@ 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 5a08a2306784..4395435af576 100644
--- a/drivers/net/ethernet/sfc/efx_cxl.c
+++ b/drivers/net/ethernet/sfc/efx_cxl.c
@@ -24,6 +24,7 @@ int efx_cxl_init(struct efx_probe_data *probe_data)
 	struct pci_dev *pci_dev = efx->pci_dev;
 	DECLARE_BITMAP(expected, CXL_MAX_CAPS);
 	DECLARE_BITMAP(found, CXL_MAX_CAPS);
+	resource_size_t max_size;
 	struct efx_cxl *cxl;
 	u16 dvsec;
 	int rc;
@@ -89,6 +90,24 @@ int efx_cxl_init(struct efx_probe_data *probe_data)
 		return rc;
 	}
 
+	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");
+		rc = PTR_ERR(cxl->cxlrd);
+		return rc;
+	}
+
+	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);
+		rc = -ENOSPC;
+		cxl_put_root_decoder(cxl->cxlrd);
+		return rc;
+	}
+
 	probe_data->cxl = cxl;
 
 	return 0;
@@ -96,6 +115,8 @@ 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