linux-kernel - Re: [PATCH v10 02/15] cxl/regs: Prepare for multiple users of register mappings

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Date:   Fri, 1 Sep 2023 10:15:27 +0100
From:   Jonathan Cameron <Jonathan.Cameron@...wei.com>
To:     Terry Bowman <terry.bowman@....com>
CC:     <alison.schofield@...el.com>, <vishal.l.verma@...el.com>,
        <ira.weiny@...el.com>, <bwidawsk@...nel.org>,
        <dan.j.williams@...el.com>, <dave.jiang@...el.com>,
        <linux-cxl@...r.kernel.org>, <rrichter@....com>,
        <linux-kernel@...r.kernel.org>, <bhelgaas@...gle.com>
Subject: Re: [PATCH v10 02/15] cxl/regs: Prepare for multiple users of
 register mappings

On Thu, 31 Aug 2023 10:20:18 -0500
Terry Bowman <terry.bowman@....com> wrote:

> From: Robert Richter <rrichter@....com>
> 
> The function devm_cxl_iomap_block() is used to map register mappings
> of CXL component or device registers. A @dev is used to unmap the IO
> regions during device removal.
> 
> Now, there are multiple devices using the register mappings. E.g. the
> RAS cap of the Component Registers is used by cxl_pci, the HDM cap
> used in cxl_mem. This could cause IO blocks not being freed and a
> subsequent reinitialization to fail if the same device is used for
> both.
> 
> To prevent that, expand cxl_map_component_regs() to pass a @dev to be
> used with devm to IO unmap. This allows to pass the device that
> actually is creating and using the IO region.
> 
> For symmetry also change the function i/f of cxl_map_device_regs().
> 
> Signed-off-by: Robert Richter <rrichter@....com>
> Signed-off-by: Terry Bowman <terry.bowman@....com>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>

I was ambiguous in reply to previous, but my RB not valid here as it
stands.  Just replying so that doesn't get lost for v11!

> ---
>  drivers/cxl/core/hdm.c  | 3 ++-
>  drivers/cxl/core/regs.c | 4 ++--
>  drivers/cxl/cxl.h       | 2 ++
>  drivers/cxl/pci.c       | 4 ++--
>  4 files changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c
> index 4449b34a80cc..17c8ba8c75e0 100644
> --- a/drivers/cxl/core/hdm.c
> +++ b/drivers/cxl/core/hdm.c
> @@ -98,7 +98,8 @@ static int map_hdm_decoder_regs(struct cxl_port *port, void __iomem *crb,
>  		return -ENODEV;
>  	}
>  
> -	return cxl_map_component_regs(&map, regs, BIT(CXL_CM_CAP_CAP_ID_HDM));
> +	return cxl_map_component_regs(&map, &port->dev, regs,
> +				      BIT(CXL_CM_CAP_CAP_ID_HDM));
>  }
>  
>  static bool should_emulate_decoders(struct cxl_endpoint_dvsec_info *info)
> diff --git a/drivers/cxl/core/regs.c b/drivers/cxl/core/regs.c
> index 6281127b3e9d..dfc3e272e7d8 100644
> --- a/drivers/cxl/core/regs.c
> +++ b/drivers/cxl/core/regs.c
> @@ -201,10 +201,10 @@ void __iomem *devm_cxl_iomap_block(struct device *dev, resource_size_t addr,
>  }
>  
>  int cxl_map_component_regs(const struct cxl_register_map *map,
> +			   struct device *dev,
>  			   struct cxl_component_regs *regs,
>  			   unsigned long map_mask)
>  {
> -	struct device *dev = map->dev;
>  	struct mapinfo {
>  		const struct cxl_reg_map *rmap;
>  		void __iomem **addr;
> @@ -235,9 +235,9 @@ int cxl_map_component_regs(const struct cxl_register_map *map,
>  EXPORT_SYMBOL_NS_GPL(cxl_map_component_regs, CXL);
>  
>  int cxl_map_device_regs(const struct cxl_register_map *map,
> +			struct device *dev,
>  			struct cxl_device_regs *regs)
>  {
> -	struct device *dev = map->dev;
>  	resource_size_t phys_addr = map->resource;
>  	struct mapinfo {
>  		const struct cxl_reg_map *rmap;
> diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
> index 76d92561af29..ec8ba9ebcf64 100644
> --- a/drivers/cxl/cxl.h
> +++ b/drivers/cxl/cxl.h
> @@ -274,9 +274,11 @@ void cxl_probe_component_regs(struct device *dev, void __iomem *base,
>  void cxl_probe_device_regs(struct device *dev, void __iomem *base,
>  			   struct cxl_device_reg_map *map);
>  int cxl_map_component_regs(const struct cxl_register_map *map,
> +			   struct device *dev,
>  			   struct cxl_component_regs *regs,
>  			   unsigned long map_mask);
>  int cxl_map_device_regs(const struct cxl_register_map *map,
> +			struct device *dev,
>  			struct cxl_device_regs *regs);
>  int cxl_map_pmu_regs(struct pci_dev *pdev, struct cxl_pmu_regs *regs,
>  		     struct cxl_register_map *map);
> diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
> index 48f88d96029d..88ddcff8a0b2 100644
> --- a/drivers/cxl/pci.c
> +++ b/drivers/cxl/pci.c
> @@ -827,7 +827,7 @@ static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>  	if (rc)
>  		return rc;
>  
> -	rc = cxl_map_device_regs(&map, &cxlds->regs.device_regs);
> +	rc = cxl_map_device_regs(&map, cxlds->dev, &cxlds->regs.device_regs);
>  	if (rc)
>  		return rc;
>  
> @@ -844,7 +844,7 @@ static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>  
>  	cxlds->component_reg_phys = map.resource;
>  
> -	rc = cxl_map_component_regs(&map, &cxlds->regs.component,
> +	rc = cxl_map_component_regs(&map, cxlds->dev, &cxlds->regs.component,
>  				    BIT(CXL_CM_CAP_CAP_ID_RAS));
>  	if (rc)
>  		dev_dbg(&pdev->dev, "Failed to map RAS capability.\n");