Re: [PATCH v5 01/12] cxl/memdev: Add support for the Inject Poison mailbox command

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

On Sun, 26 Mar 2023 22:03:07 -0700
alison.schofield@intel.com wrote:

> From: Alison Schofield <alison.schofield@intel.com>
> 
> CXL devices optionally support the INJECT POISON mailbox command. Add
> memdev driver support for the mailbox command.
> 
> Per the CXL Specification (3.0 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.
> 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.
> 
> If the address is not contained in the device's dpa resource, or is
> not 64 byte aligned, return -EINVAL without issuing the mbox command.
> 
> Poison injection is intended for debug only and will be exposed to
> userspace through debugfs. Restrict compilation to CONFIG_DEBUG_FS.
> 
> Signed-off-by: Alison Schofield <alison.schofield@intel.com>
LGTM
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

> ---
>  drivers/cxl/core/memdev.c | 55 +++++++++++++++++++++++++++++++++++++++
>  drivers/cxl/cxlmem.h      |  6 +++++
>  2 files changed, 61 insertions(+)
> 
> diff --git a/drivers/cxl/core/memdev.c b/drivers/cxl/core/memdev.c
> index f26b5b6cda10..3b3ac2868848 100644
> --- a/drivers/cxl/core/memdev.c
> +++ b/drivers/cxl/core/memdev.c
> @@ -213,6 +213,61 @@ ssize_t cxl_trigger_poison_list(struct device *dev,
>  }
>  EXPORT_SYMBOL_NS_GPL(cxl_trigger_poison_list, CXL);
>  
> +static int cxl_validate_poison_dpa(struct cxl_memdev *cxlmd, u64 dpa)
> +{
> +	struct cxl_dev_state *cxlds = cxlmd->cxlds;
> +
> +	if (!IS_ENABLED(CONFIG_DEBUG_FS))
> +		return 0;
> +
> +	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 (!IS_ALIGNED(dpa, 64)) {
> +		dev_dbg(cxlds->dev, "dpa:0x%llx is not 64-byte aligned\n", dpa);
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
> +int cxl_inject_poison(struct device *dev, u64 dpa)
> +{
> +	struct cxl_memdev *cxlmd = to_cxl_memdev(dev);
> +	struct cxl_mbox_inject_poison inject;
> +	struct cxl_mbox_cmd mbox_cmd;
> +	int rc;
> +
> +	if (!IS_ENABLED(CONFIG_DEBUG_FS))
> +		return 0;
> +
> +	down_read(&cxl_dpa_rwsem);
> +	rc = cxl_validate_poison_dpa(cxlmd, dpa);
> +	if (rc)
> +		goto out;
> +
> +	inject = (struct cxl_mbox_inject_poison) {
> +		.address = cpu_to_le64(dpa)
> +	};
> +	mbox_cmd = (struct cxl_mbox_cmd) {
> +		.opcode = CXL_MBOX_OP_INJECT_POISON,
> +		.size_in = sizeof(inject),
> +		.payload_in = &inject,
> +	};
> +	rc = cxl_internal_send_cmd(cxlmd->cxlds, &mbox_cmd);
> +out:
> +	up_read(&cxl_dpa_rwsem);
> +
> +	return rc;
> +}
> +EXPORT_SYMBOL_NS_GPL(cxl_inject_poison, CXL);
> +
>  static struct attribute *cxl_memdev_attributes[] = {
>  	&dev_attr_serial.attr,
>  	&dev_attr_firmware_version.attr,
> diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
> index 5febaa3f9b04..527efef2d700 100644
> --- a/drivers/cxl/cxlmem.h
> +++ b/drivers/cxl/cxlmem.h
> @@ -602,6 +602,11 @@ 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 */
> +struct cxl_mbox_inject_poison {
> +	__le64 address;
> +};
> +
>  /**
>   * struct cxl_mem_command - Driver representation of a memory device command
>   * @info: Command information as it exists for the UAPI
> @@ -678,6 +683,7 @@ int cxl_mem_get_poison(struct cxl_memdev *cxlmd, u64 offset, u64 len,
>  ssize_t cxl_trigger_poison_list(struct device *dev,
>  				struct device_attribute *attr, const char *buf,
>  				size_t len);
> +int cxl_inject_poison(struct device *dev, u64 dpa);
>  
>  #ifdef CONFIG_CXL_SUSPEND
>  void cxl_mem_active_inc(void);