Re: [PATCH v4 20/23] cxl/pci: Prepare for logging RCH downstream port protocol errors

[Terry Bowman]

Hi Jonathan, thanks for reviewing.

On 6/1/23 08:49, Jonathan Cameron wrote:
> On Tue, 23 May 2023 18:22:11 -0500
> Terry Bowman <terry.bowman@xxxxxxx> wrote:
> 
> The title is very vague.  Can it be more specific to what
> is in this patch?  The description makes it seem like a bunch of
> unconnected things, but in reality they all chain together
> to get the registers and disable the interrupt.
> 

How about I split this into 2 patches (along lines of register mapping
and root port interrupt disable) and title as:
cxl/pci: Map RCH downstream registers for AER protocol error logging
cxl/pci: Disable root port interrupts in RCH mode

>> The restricted CXL host (RCH) error handler will log protocol errors
>> using AER and RAS status registers. The AER and RAS registers need
>> to be virtually memory mapped before enabling interrupts. Update
>> __devm_cxl_add_dport() to include RCH RAS and AER mapping.
>>
>> Add 'struct cxl_regs' to 'struct cxl_dport' for saving a unique copy of
>> the RCH downstream port's mapped registers.
>>
>> The RCH contains root command AER registers that should not be
>> enabled.[1] Disable these to prevent root port interrupt generation.
> 
>>
>> [1] CXL3.0 - 12.2.1.1 RCH Downstream Port-detected Errors
> I just noticed this formatting of CXL3.0
> It's CXL 3.0 or CXL rev 3.0 in most existing references in the tree so
> good to keep to one of those instead of introducing another form
> 

Ok, I will change.

>>
>> Co-developed-by: Robert Richter <rrichter@xxxxxxx>
>> Signed-off-by: Robert Richter <rrichter@xxxxxxx>
>> Signed-off-by: Terry Bowman <terry.bowman@xxxxxxx>
>> ---
>>  drivers/cxl/core/port.c | 64 +++++++++++++++++++++++++++++++++++++++++
>>  drivers/cxl/core/regs.c |  1 +
>>  drivers/cxl/cxl.h       | 11 +++++++
>>  3 files changed, 76 insertions(+)
>>
>> diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
>> index d147f08780d0..80c643254b86 100644
>> --- a/drivers/cxl/core/port.c
>> +++ b/drivers/cxl/core/port.c
>> @@ -8,6 +8,7 @@
>>  #include <linux/pci.h>
>>  #include <linux/slab.h>
>>  #include <linux/idr.h>
>> +#include <linux/aer.h>
>>  #include <cxlmem.h>
>>  #include <cxlpci.h>
>>  #include <cxl.h>
>> @@ -940,6 +941,63 @@ static void cxl_dport_unlink(void *data)
>>  	sysfs_remove_link(&port->dev.kobj, link_name);
>>  }
>>  
>> +static void cxl_disable_rch_root_ints(struct cxl_dport *dport)
>> +{
>> +	void __iomem *aer_base = dport->regs.dport_aer;
>> +	u32 aer_cmd_mask, aer_cmd;
>> +
>> +	if (!dport->rch || !aer_base)
>> +		return;
>> +
>> +	/*
>> +	 * Disable RCH root port command interrupts.
>> +	 * CXL3.0 12.2.1.1 - RCH Downstream Port-detected Errors
> 
> Space after CXL?
> 
Ok.

Regards,
Terry

>> +	 *
>> +	 * This sequnce may not be necessary. CXL spec states disabling
>> +	 * the root cmd register's interrupts is required. But, PCI spec
>> +	 * shows these are disabled by default on reset.
>> +	 */
>> +	aer_cmd_mask = (PCI_ERR_ROOT_CMD_COR_EN |
>> +			PCI_ERR_ROOT_CMD_NONFATAL_EN |
>> +			PCI_ERR_ROOT_CMD_FATAL_EN);
>> +	aer_cmd = readl(aer_base + PCI_ERR_ROOT_COMMAND);
>> +	aer_cmd &= ~aer_cmd_mask;
>> +	writel(aer_cmd, aer_base + PCI_ERR_ROOT_COMMAND);
>> +}
>> +
>> +static int cxl_dport_map_rch_aer(struct cxl_dport *dport)
>> +{
>> +	struct cxl_rcrb_info *ri = &dport->rcrb;
>> +	resource_size_t aer_phys;
>> +	void __iomem *dport_aer;
>> +
>> +	if (!dport->rch || !ri->aer_cap)
>> +		return -ENODEV;
>> +
>> +	aer_phys = ri->aer_cap + ri->base;
>> +	dport_aer = devm_cxl_iomap_block(dport->dev, aer_phys,
>> +					 sizeof(struct aer_capability_regs));
>> +	if (!dport_aer)
>> +		return -ENOMEM;
>> +
>> +	dport->regs.dport_aer = dport_aer;
>> +
>> +	return 0;
>> +}
>> +
>> +static int cxl_dport_map_regs(struct cxl_dport *dport)
>> +{
>> +	struct cxl_register_map *map = &dport->comp_map;
>> +
>> +	if (!map->component_map.ras.valid)
>> +		dev_dbg(map->dev, "RAS registers not found\n");
>> +	else if (cxl_map_component_regs(map, &dport->regs.component,
>> +					BIT(CXL_CM_CAP_CAP_ID_RAS)))
>> +		dev_dbg(dport->dev, "Failed to map RAS capability.\n");
>> +
>> +	return cxl_dport_map_rch_aer(dport);
>> +}
>> +
>>  static struct cxl_dport *
>>  __devm_cxl_add_dport(struct cxl_port *port, struct device *dport_dev,
>>  		     int port_id, resource_size_t component_reg_phys,
>> @@ -994,6 +1052,12 @@ __devm_cxl_add_dport(struct cxl_port *port, struct device *dport_dev,
>>  	if (rc && rc != -ENODEV)
>>  		return ERR_PTR(rc);
>>  
>> +	rc = cxl_dport_map_regs(dport);
>> +	if (rc && rc != -ENODEV)
>> +		return ERR_PTR(rc);
>> +
>> +	cxl_disable_rch_root_ints(dport);
>> +
>>  	cond_cxl_root_lock(port);
>>  	rc = add_dport(port, dport);
>>  	cond_cxl_root_unlock(port);
>> diff --git a/drivers/cxl/core/regs.c b/drivers/cxl/core/regs.c
>> index 045abc11add8..b34f9e04cae4 100644
>> --- a/drivers/cxl/core/regs.c
>> +++ b/drivers/cxl/core/regs.c
>> @@ -198,6 +198,7 @@ void __iomem *devm_cxl_iomap_block(struct device *dev, resource_size_t addr,
>>  
>>  	return ret_val;
>>  }
>> +EXPORT_SYMBOL_NS_GPL(devm_cxl_iomap_block, CXL);
>>  
>>  int cxl_map_component_regs(struct cxl_register_map *map,
>>  			   struct cxl_component_regs *regs,
>> diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
>> index 6134644b51f8..0e0bcbefefaf 100644
>> --- a/drivers/cxl/cxl.h
>> +++ b/drivers/cxl/cxl.h
>> @@ -209,6 +209,13 @@ struct cxl_regs {
>>  	struct_group_tagged(cxl_device_regs, device_regs,
>>  		void __iomem *status, *mbox, *memdev;
>>  	);
>> +	/*
>> +	 * RCH downstream port specific RAS register
>> +	 * @aer: CXL 3.0 8.2.1.1 RCH Downstream Port RCRB
>> +	 */
>> +	struct_group_tagged(cxl_rch_regs, rch_regs,
>> +		void __iomem *dport_aer;
>> +	);
>>  };
>>  
>>  struct cxl_reg_map {
>> @@ -255,6 +262,8 @@ void cxl_probe_component_regs(struct device *dev, void __iomem *base,
>>  			      struct cxl_component_reg_map *map);
>>  void cxl_probe_device_regs(struct device *dev, void __iomem *base,
>>  			   struct cxl_device_reg_map *map);
>> +void __iomem *devm_cxl_iomap_block(struct device *dev, resource_size_t addr,
>> +				   resource_size_t length);
>>  int cxl_map_component_regs(struct cxl_register_map *map,
>>  			   struct cxl_component_regs *regs,
>>  			   unsigned long map_mask);
>> @@ -603,6 +612,7 @@ struct cxl_rcrb_info {
>>   * @port_id: unique hardware identifier for dport in decoder target list
>>   * @rch: Indicate whether this dport was enumerated in RCH or VH mode
>>   * @rcrb: Data about the Root Complex Register Block layout
>> + * @regs: Dport parsed register blocks
>>   */
>>  struct cxl_dport {
>>  	struct device *dev;
>> @@ -611,6 +621,7 @@ struct cxl_dport {
>>  	int port_id;
>>  	bool rch;
>>  	struct cxl_rcrb_info rcrb;
>> +	struct cxl_regs regs;
>>  };
>>  
>>  /**
>