linux-kernel - Re: [PATCH v14 01/34] PCI: Move CXL DVSEC definitions into uapi/linux/pci

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Message-ID: <20260122185847.GA36294@bhelgaas>
Date: Thu, 22 Jan 2026 12:58:47 -0600
From: Bjorn Helgaas <helgaas@...nel.org>
To: Terry Bowman <terry.bowman@....com>
Cc: dave@...olabs.net, jonathan.cameron@...wei.com, dave.jiang@...el.com,
	alison.schofield@...el.com, dan.j.williams@...el.com,
	bhelgaas@...gle.com, shiju.jose@...wei.com, ming.li@...omail.com,
	Smita.KoralahalliChannabasappa@....com, rrichter@....com,
	dan.carpenter@...aro.org, PradeepVineshReddy.Kodamati@....com,
	lukas@...ner.de, Benjamin.Cheatham@....com,
	sathyanarayanan.kuppuswamy@...ux.intel.com,
	linux-cxl@...r.kernel.org, vishal.l.verma@...el.com,
	alucerop@....com, ira.weiny@...el.com, linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org
Subject: Re: [PATCH v14 01/34] PCI: Move CXL DVSEC definitions into
 uapi/linux/pci_regs.h

On Wed, Jan 14, 2026 at 12:20:22PM -0600, Terry Bowman wrote:
> The CXL DVSECs are currently defined in cxl/core/cxlpci.h. These are not
> accessible to other subsystems. Move these to uapi/linux/pci_regs.h.

I'm looking a little bit askance at adding things to
uapi/linux/pci_regs.h and then renaming them.  I know it's OCD to
worry about that momentary blip, but changes in uapi potentially break
userspace.

Maybe we could rename them first, then move them to pci_regs.h?

Either way:

Acked-by: Bjorn Helgaas <bhelgaas@...gle.com>

> The CXL DVSEC definitions will be renamed and reformatted to fit better
> with existing defines.
> 
> Signed-off-by: Terry Bowman <terry.bowman@....com>
> Reviewed-by: Dave Jiang <dave.jiang@...el.com>
> Reviewed-by: Jonathan Cameron <jonathan.cameron@...wei.com>
> Reviewed-by: Dan Williams <dan.j.williams@...el.com>
> 
> ----
> 
> Changes in v13->v14:
> - Add Jonathan's and Dan's review-by
> - Update commit title prefix (Bjorn)
> - Revert format fix for cxl_sbr_masked() (Jonathan)
> - Update 'Compute Express Link' comment block (Jonathan)
> - Move PCI_DVSEC_CXL_FLEXBUS definitions to later patch where
>   used (Jonathan)
> - Removed stray change (Bjorn)
> 
> Changes in v12->v13:
> - Add Dave Jiang's reviewed-by
> - Remove changes to existing PCI_DVSEC_CXL_PORT* defines. Update commit
>   message. (Jonathan)
> 
> Changes in v11 -> v12:
> - Change formatting to be same as existing definitions
> - Change GENMASK() -> __GENMASK() and BIT() to _BITUL()
> 
> Changes in v10 -> v11:
> - New commit
> ---
>  drivers/cxl/cxlpci.h          | 53 -----------------------------
>  include/uapi/linux/pci_regs.h | 64 ++++++++++++++++++++++++++++++++---
>  2 files changed, 59 insertions(+), 58 deletions(-)
> 
> diff --git a/drivers/cxl/cxlpci.h b/drivers/cxl/cxlpci.h
> index 1d526bea8431..cdb7cf3dbcb4 100644
> --- a/drivers/cxl/cxlpci.h
> +++ b/drivers/cxl/cxlpci.h
> @@ -7,59 +7,6 @@
>  
>  #define CXL_MEMORY_PROGIF	0x10
>  
> -/*
> - * See section 8.1 Configuration Space Registers in the CXL 2.0
> - * Specification. Names are taken straight from the specification with "CXL" and
> - * "DVSEC" redundancies removed. When obvious, abbreviations may be used.
> - */
> -#define PCI_DVSEC_HEADER1_LENGTH_MASK	GENMASK(31, 20)
> -
> -/* CXL 2.0 8.1.3: PCIe DVSEC for CXL Device */
> -#define CXL_DVSEC_PCIE_DEVICE					0
> -#define   CXL_DVSEC_CAP_OFFSET		0xA
> -#define     CXL_DVSEC_MEM_CAPABLE	BIT(2)
> -#define     CXL_DVSEC_HDM_COUNT_MASK	GENMASK(5, 4)
> -#define   CXL_DVSEC_CTRL_OFFSET		0xC
> -#define     CXL_DVSEC_MEM_ENABLE	BIT(2)
> -#define   CXL_DVSEC_RANGE_SIZE_HIGH(i)	(0x18 + (i * 0x10))
> -#define   CXL_DVSEC_RANGE_SIZE_LOW(i)	(0x1C + (i * 0x10))
> -#define     CXL_DVSEC_MEM_INFO_VALID	BIT(0)
> -#define     CXL_DVSEC_MEM_ACTIVE	BIT(1)
> -#define     CXL_DVSEC_MEM_SIZE_LOW_MASK	GENMASK(31, 28)
> -#define   CXL_DVSEC_RANGE_BASE_HIGH(i)	(0x20 + (i * 0x10))
> -#define   CXL_DVSEC_RANGE_BASE_LOW(i)	(0x24 + (i * 0x10))
> -#define     CXL_DVSEC_MEM_BASE_LOW_MASK	GENMASK(31, 28)
> -
> -#define CXL_DVSEC_RANGE_MAX		2
> -
> -/* CXL 2.0 8.1.4: Non-CXL Function Map DVSEC */
> -#define CXL_DVSEC_FUNCTION_MAP					2
> -
> -/* CXL 2.0 8.1.5: CXL 2.0 Extensions DVSEC for Ports */
> -#define CXL_DVSEC_PORT_EXTENSIONS				3
> -
> -/* CXL 2.0 8.1.6: GPF DVSEC for CXL Port */
> -#define CXL_DVSEC_PORT_GPF					4
> -#define   CXL_DVSEC_PORT_GPF_PHASE_1_CONTROL_OFFSET		0x0C
> -#define     CXL_DVSEC_PORT_GPF_PHASE_1_TMO_BASE_MASK		GENMASK(3, 0)
> -#define     CXL_DVSEC_PORT_GPF_PHASE_1_TMO_SCALE_MASK		GENMASK(11, 8)
> -#define   CXL_DVSEC_PORT_GPF_PHASE_2_CONTROL_OFFSET		0xE
> -#define     CXL_DVSEC_PORT_GPF_PHASE_2_TMO_BASE_MASK		GENMASK(3, 0)
> -#define     CXL_DVSEC_PORT_GPF_PHASE_2_TMO_SCALE_MASK		GENMASK(11, 8)
> -
> -/* CXL 2.0 8.1.7: GPF DVSEC for CXL Device */
> -#define CXL_DVSEC_DEVICE_GPF					5
> -
> -/* CXL 2.0 8.1.8: PCIe DVSEC for Flex Bus Port */
> -#define CXL_DVSEC_PCIE_FLEXBUS_PORT				7
> -
> -/* CXL 2.0 8.1.9: Register Locator DVSEC */
> -#define CXL_DVSEC_REG_LOCATOR					8
> -#define   CXL_DVSEC_REG_LOCATOR_BLOCK1_OFFSET			0xC
> -#define     CXL_DVSEC_REG_LOCATOR_BIR_MASK			GENMASK(2, 0)
> -#define	    CXL_DVSEC_REG_LOCATOR_BLOCK_ID_MASK			GENMASK(15, 8)
> -#define     CXL_DVSEC_REG_LOCATOR_BLOCK_OFF_LOW_MASK		GENMASK(31, 16)
> -
>  /*
>   * NOTE: Currently all the functions which are enabled for CXL require their
>   * vectors to be in the first 16.  Use this as the default max.
> diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
> index 3add74ae2594..6c4b6f19b18e 100644
> --- a/include/uapi/linux/pci_regs.h
> +++ b/include/uapi/linux/pci_regs.h
> @@ -1253,11 +1253,6 @@
>  #define PCI_DEV3_STA		0x0c	/* Device 3 Status Register */
>  #define  PCI_DEV3_STA_SEGMENT	0x8	/* Segment Captured (end-to-end flit-mode detected) */
>  
> -/* Compute Express Link (CXL r3.1, sec 8.1.5) */
> -#define PCI_DVSEC_CXL_PORT				3
> -#define PCI_DVSEC_CXL_PORT_CTL				0x0c
> -#define PCI_DVSEC_CXL_PORT_CTL_UNMASK_SBR		0x00000001
> -
>  /* Integrity and Data Encryption Extended Capability */
>  #define PCI_IDE_CAP			0x04
>  #define  PCI_IDE_CAP_LINK		0x1  /* Link IDE Stream Supported */
> @@ -1338,4 +1333,63 @@
>  #define  PCI_IDE_SEL_ADDR_3(x)		(28 + (x) * PCI_IDE_SEL_ADDR_BLOCK_SIZE)
>  #define PCI_IDE_SEL_BLOCK_SIZE(nr_assoc)  (20 + PCI_IDE_SEL_ADDR_BLOCK_SIZE * (nr_assoc))
>  
> +/* Compute Express Link (CXL r3.1, sec 8.1.5) */
> +#define PCI_DVSEC_CXL_PORT				3
> +#define PCI_DVSEC_CXL_PORT_CTL				0x0c
> +#define PCI_DVSEC_CXL_PORT_CTL_UNMASK_SBR		0x00000001
> +
> +/*
> + * Compute Express Link (CXL r3.2, sec 8.1)
> + *
> + * Note that CXL DVSEC id 3 and 7 to be ignored when the CXL link state
> + * is "disconnected" (CXL r3.2, sec 9.12.3). Re-enumerate these
> + * registers on downstream link-up events.
> + */
> +#define PCI_DVSEC_HEADER1_LENGTH_MASK  __GENMASK(31, 20)
> +
> +/* CXL 3.2 8.1.3: PCIe DVSEC for CXL Device */
> +#define CXL_DVSEC_PCIE_DEVICE				0
> +#define  CXL_DVSEC_CAP_OFFSET				0xA
> +#define   CXL_DVSEC_MEM_CAPABLE				_BITUL(2)
> +#define   CXL_DVSEC_HDM_COUNT_MASK			__GENMASK(5, 4)
> +#define  CXL_DVSEC_CTRL_OFFSET				0xC
> +#define   CXL_DVSEC_MEM_ENABLE				_BITUL(2)
> +#define  CXL_DVSEC_RANGE_SIZE_HIGH(i)			(0x18 + (i * 0x10))
> +#define  CXL_DVSEC_RANGE_SIZE_LOW(i)			(0x1C + (i * 0x10))
> +#define   CXL_DVSEC_MEM_INFO_VALID			_BITUL(0)
> +#define   CXL_DVSEC_MEM_ACTIVE				_BITUL(1)
> +#define   CXL_DVSEC_MEM_SIZE_LOW_MASK			__GENMASK(31, 28)
> +#define  CXL_DVSEC_RANGE_BASE_HIGH(i)			(0x20 + (i * 0x10))
> +#define  CXL_DVSEC_RANGE_BASE_LOW(i)			(0x24 + (i * 0x10))
> +#define   CXL_DVSEC_MEM_BASE_LOW_MASK			__GENMASK(31, 28)
> +
> +#define CXL_DVSEC_RANGE_MAX				2
> +
> +/* CXL 3.2 8.1.4: Non-CXL Function Map DVSEC */
> +#define CXL_DVSEC_FUNCTION_MAP				2
> +
> +/* CXL 3.2 8.1.5: Extensions DVSEC for Ports */
> +#define CXL_DVSEC_PORT					3
> +#define   CXL_DVSEC_PORT_CTL				0x0c
> +#define    CXL_DVSEC_PORT_CTL_UNMASK_SBR		0x00000001
> +
> +/* CXL 3.2 8.1.6: GPF DVSEC for CXL Port */
> +#define CXL_DVSEC_PORT_GPF				4
> +#define  CXL_DVSEC_PORT_GPF_PHASE_1_CONTROL_OFFSET	0x0C
> +#define   CXL_DVSEC_PORT_GPF_PHASE_1_TMO_BASE_MASK	__GENMASK(3, 0)
> +#define   CXL_DVSEC_PORT_GPF_PHASE_1_TMO_SCALE_MASK	__GENMASK(11, 8)
> +#define  CXL_DVSEC_PORT_GPF_PHASE_2_CONTROL_OFFSET	0xE
> +#define   CXL_DVSEC_PORT_GPF_PHASE_2_TMO_BASE_MASK	__GENMASK(3, 0)
> +#define   CXL_DVSEC_PORT_GPF_PHASE_2_TMO_SCALE_MASK	__GENMASK(11, 8)
> +
> +/* CXL 3.2 8.1.7: GPF DVSEC for CXL Device */
> +#define CXL_DVSEC_DEVICE_GPF				5
> +
> +/* CXL 3.2 8.1.9: Register Locator DVSEC */
> +#define CXL_DVSEC_REG_LOCATOR				8
> +#define  CXL_DVSEC_REG_LOCATOR_BLOCK1_OFFSET		0xC
> +#define   CXL_DVSEC_REG_LOCATOR_BIR_MASK		__GENMASK(2, 0)
> +#define   CXL_DVSEC_REG_LOCATOR_BLOCK_ID_MASK		__GENMASK(15, 8)
> +#define   CXL_DVSEC_REG_LOCATOR_BLOCK_OFF_LOW_MASK	__GENMASK(31, 16)
> +
>  #endif /* LINUX_PCI_REGS_H */
> -- 
> 2.34.1
>