Re: [PATCH 1/5] cxl/memdev: Add support for the Inject Poison mailbox command

[Jonathan Cameron <Jonathan.Cameron@Huawei.com>]

On Tue, 29 Nov 2022 20:34:33 -0800
alison.schofield@intel.com wrote:

> From: Alison Schofield <alison.schofield@intel.com>
> 
> CXL devices optionally support the INJECT POISON mailbox command. Add
> a sysfs attribute and memdev driver support for injecting poison.
> 
> When a Device Physical Address (DPA) is written to the inject_poison
> sysfs attribute send an inject poison command to the device for the
> specified address.
> 
> Per the CXL Specification (8.2.9.8.4.2), after receiving a valid
> inject poison request, the device will return poison when the address
> is accessed through the CXL.mem bus. Injecting poison adds the address
> to the device's Poison List and the error source is set to injected
> error. In addition, the device adds a poison creation event to its
> internal Informational Event log, updates the Event Status register,
> and if configured, interrupts the host.
> 
> Also, per the CXL Specification, it is not an error to inject poison
> into an address that already has poison present and no error is returned
> from the device. The memdev driver performs basic sanity checking on the
> address, however, it does not go as far as reading the poison list to see
> if the address is on the list. That discovery is left to the device.
> 
> The inject_poison attribute is only visible for devices supporting
> the capability.
> 
> Signed-off-by: Alison Schofield <alison.schofield@intel.com>
A few trivial things inline.  With those fixes LGTM

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

> ---
>  Documentation/ABI/testing/sysfs-bus-cxl | 19 +++++++++
>  drivers/cxl/core/memdev.c               | 53 +++++++++++++++++++++++++
>  drivers/cxl/cxlmem.h                    |  3 ++
>  3 files changed, 75 insertions(+)
> 
> diff --git a/Documentation/ABI/testing/sysfs-bus-cxl b/Documentation/ABI/testing/sysfs-bus-cxl
> index b715a4609718..20db97f7a1aa 100644
> --- a/Documentation/ABI/testing/sysfs-bus-cxl
> +++ b/Documentation/ABI/testing/sysfs-bus-cxl
> @@ -416,3 +416,22 @@ Description:
>  		if accessed, and the source of the poison. The retrieved
>  		errors are logged as kernel trace events with the label
>  		'cxl_poison'.
> +
> +
> +What:		/sys/bus/cxl/devices/memX/inject_poison
> +Date:		December, 2022
> +KernelVersion:	v6.2
> +Contact:	linux-cxl@vger.kernel.org
> +Description:
> +		(WO) When a Device Physical Address (DPA) is written to this
> +		attribute the memdev driver sends an inject poison command to
> +		the device for the specified address. If successful, the device
> +		returns poison when the address is accessed through the CXL.mem
> +		bus. Injecting poison adds the address to the device's Poison
> +		List and the error source is set to injected error. In addition,
"set to Injected."

perhaps to match spec naming in Media Error Record.

> +		the device adds a poison creation event to its internal
> +		Informational Event log, updates the Event Status register, and
> +		if configured, interrupts the host. It is not an error to inject
> +		poison into an address that already has poison present and no
> +		error is returned. The inject_poison attribute is only visible
> +                for devices supporting the capability.

White space issues (spaces instead of tabs?)

Add something about the masked bits / granularity of addresses that are accepted.

> diff --git a/drivers/cxl/core/memdev.c b/drivers/cxl/core/memdev.c
> index d08b7295a01c..71130813030f 100644
> --- a/drivers/cxl/core/memdev.c
> +++ b/drivers/cxl/core/memdev.c
> @@ -142,6 +142,51 @@ static ssize_t trigger_poison_list_store(struct device *dev,
>  }
>  static DEVICE_ATTR_WO(trigger_poison_list);
>  
> +static int cxl_validate_poison_dpa(struct cxl_dev_state *cxlds, u64 dpa)
> +{
> +	if (!resource_size(&cxlds->dpa_res)) {
> +		dev_dbg(cxlds->dev, "device has no dpa resource\n");
> +		return -EINVAL;
> +	}
> +	if (dpa < cxlds->dpa_res.start || dpa > cxlds->dpa_res.end) {
> +		dev_dbg(cxlds->dev, "dpa:0x%llx not in resource:%pR\n",
> +			dpa, &cxlds->dpa_res);
> +		return -EINVAL;
> +	}
> +	if ((dpa & CXL_POISON_INJECT_RESERVED) != 0) {
> +		dev_dbg(cxlds->dev, "dpa reserve bit(s) [5:0] set 0x%llx\n",
> +			dpa);
> +		return -EINVAL;
> +	}
> +	return 0;
> +}
> +
> +static ssize_t inject_poison_store(struct device *dev,
> +				   struct device_attribute *attr,
> +				   const char *buf, size_t len)
> +{
> +	struct cxl_memdev *cxlmd = to_cxl_memdev(dev);
> +	struct cxl_dev_state *cxlds = cxlmd->cxlds;
> +	u64 dpa;
> +	int rc;
> +
> +	rc = kstrtou64(buf, 0, &dpa);
> +	if (rc)
> +		return rc;
> +	rc = cxl_validate_poison_dpa(cxlds, dpa);
> +	if (rc)
> +		return rc;
> +
> +	dpa = cpu_to_le64(dpa);
> +	rc = cxl_mbox_send_cmd(cxlds, CXL_MBOX_OP_INJECT_POISON, &dpa,

Endianness?

> +			       sizeof(dpa), NULL, cxlds->payload_size);
> +	if (rc)
> +		return rc;
> +
> +	return len;
> +}
> +static DEVICE_ATTR_WO(inject_poison);
> +
>  static struct attribute *cxl_memdev_attributes[] = {
>  	&dev_attr_serial.attr,
>  	&dev_attr_firmware_version.attr,
> @@ -149,6 +194,7 @@ static struct attribute *cxl_memdev_attributes[] = {
>  	&dev_attr_label_storage_size.attr,
>  	&dev_attr_numa_node.attr,
>  	&dev_attr_trigger_poison_list.attr,
> +	&dev_attr_inject_poison.attr,
>  	NULL,
>  };
>  
> @@ -175,6 +221,13 @@ static umode_t cxl_memdev_visible(struct kobject *kobj, struct attribute *a,
>  			      to_cxl_memdev(dev)->cxlds->enabled_cmds))
>  			return 0;
>  	}
> +	if (a == &dev_attr_inject_poison.attr) {
> +		struct device *dev = kobj_to_dev(kobj);
> +
> +		if (!test_bit(CXL_MEM_COMMAND_ID_INJECT_POISON,
> +			      to_cxl_memdev(dev)->cxlds->enabled_cmds))
> +			return 0;
> +	}
>  	return a->mode;
>  }
>  
> diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
> index 19a9e545ac19..0d4c34be7335 100644
> --- a/drivers/cxl/cxlmem.h
> +++ b/drivers/cxl/cxlmem.h
> @@ -396,6 +396,9 @@ struct cxl_mbox_poison_payload_out {
>  #define CXL_POISON_SOURCE_INJECTED	3
>  #define CXL_POISON_SOURCE_VENDOR	7
>  
> +/* Inject & Clear Poison  CXL 3.0 Spec 8.2.9.8.4.2/3 */
> +#define CXL_POISON_INJECT_RESERVED	GENMASK_ULL(5, 0)
> +
>  /**
>   * struct cxl_mem_command - Driver representation of a memory device command
>   * @info: Command information as it exists for the UAPI