Re: [PATCH v10 10/31] cxl/mem: Configure dynamic capacity interrupts

[Dave Jiang <dave.jiang@intel.com>]

On 5/23/26 2:43 AM, Anisa Su wrote:
> From: Ira Weiny <ira.weiny@intel.com>
> 
> Dynamic Capacity Devices (DCD) support extent change notifications
> through the event log mechanism.  The interrupt mailbox commands were
> extended in CXL 3.1 to support these notifications.  Firmware can't
> configure DCD events to be FW controlled but can retain control of
> memory events.
> 
> Configure DCD event log interrupts on devices supporting dynamic
> capacity.  Disable DCD if interrupts are not supported.
> 
> Care is taken to preserve the interrupt policy set by the FW if FW first
> has been selected by the BIOS.
> 
> Accept the 4-byte CXL 2.0 reply on GET Event Interrupt Policy by setting
> min_out to CXL_EVENT_INT_POLICY_BASE_SIZE; pre-CXL 3.1 firmware omits
> dcd_settings and would otherwise fail the size check.
> 
> Based on an original patch by Navneet Singh.
> 
> Signed-off-by: Ira Weiny <ira.weiny@intel.com>
> Signed-off-by: Anisa Su <anisa.su@samsung.com>
> 
> ---
> Changes:
> [anisa: rebase]
> [anisa: accept 4-byte CXL 2.0 GET reply via min_out]
> [anisa: drop Reviewed-by tags now that the patch carries new changes]
> ---
>  drivers/cxl/cxlmem.h |  2 ++
>  drivers/cxl/pci.c    | 75 ++++++++++++++++++++++++++++++++++++--------
>  2 files changed, 64 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
> index 10175ca3b7ee..65c009b02da6 100644
> --- a/drivers/cxl/cxlmem.h
> +++ b/drivers/cxl/cxlmem.h
> @@ -218,7 +218,9 @@ struct cxl_event_interrupt_policy {
>  	u8 warn_settings;
>  	u8 failure_settings;
>  	u8 fatal_settings;
> +	u8 dcd_settings;
>  } __packed;
> +#define CXL_EVENT_INT_POLICY_BASE_SIZE 4 /* info, warn, failure, fatal */
>  
>  /**
>   * struct cxl_event_state - Event log driver state
> diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
> index 8d12c684d670..83617439bbd3 100644
> --- a/drivers/cxl/pci.c
> +++ b/drivers/cxl/pci.c
> @@ -557,6 +557,8 @@ static int cxl_event_get_int_policy(struct cxl_memdev_state *mds,
>  		.opcode = CXL_MBOX_OP_GET_EVT_INT_POLICY,
>  		.payload_out = policy,
>  		.size_out = sizeof(*policy),
> +		/* CXL 2.0 firmware omits dcd_settings; accept the shorter reply */
> +		.min_out = CXL_EVENT_INT_POLICY_BASE_SIZE,
>  	};
>  	int rc;
>  
> @@ -569,23 +571,34 @@ static int cxl_event_get_int_policy(struct cxl_memdev_state *mds,
>  }
>  
>  static int cxl_event_config_msgnums(struct cxl_memdev_state *mds,
> -				    struct cxl_event_interrupt_policy *policy)
> +				    struct cxl_event_interrupt_policy *policy,
> +				    bool native_cxl)
>  {
>  	struct cxl_mailbox *cxl_mbox = &mds->cxlds.cxl_mbox;
> +	size_t size_in = CXL_EVENT_INT_POLICY_BASE_SIZE;
>  	struct cxl_mbox_cmd mbox_cmd;
>  	int rc;
>  
> -	*policy = (struct cxl_event_interrupt_policy) {
> -		.info_settings = CXL_INT_MSI_MSIX,
> -		.warn_settings = CXL_INT_MSI_MSIX,
> -		.failure_settings = CXL_INT_MSI_MSIX,
> -		.fatal_settings = CXL_INT_MSI_MSIX,
> -	};
> +	/* memory event policy is left if FW has control */
> +	if (native_cxl) {
> +		*policy = (struct cxl_event_interrupt_policy) {
> +			.info_settings = CXL_INT_MSI_MSIX,
> +			.warn_settings = CXL_INT_MSI_MSIX,
> +			.failure_settings = CXL_INT_MSI_MSIX,
> +			.fatal_settings = CXL_INT_MSI_MSIX,
> +			.dcd_settings = 0,
> +		};
> +	}
> +
> +	if (cxl_dcd_supported(mds)) {
> +		policy->dcd_settings = CXL_INT_MSI_MSIX;
> +		size_in += sizeof(policy->dcd_settings);
> +	}
>  
>  	mbox_cmd = (struct cxl_mbox_cmd) {
>  		.opcode = CXL_MBOX_OP_SET_EVT_INT_POLICY,
>  		.payload_in = policy,
> -		.size_in = sizeof(*policy),
> +		.size_in = size_in,
>  	};
>  
>  	rc = cxl_internal_send_cmd(cxl_mbox, &mbox_cmd);
> @@ -632,6 +645,30 @@ static int cxl_event_irqsetup(struct cxl_memdev_state *mds,
>  	return 0;
>  }
>  
> +static int cxl_irqsetup(struct cxl_memdev_state *mds,
> +			struct cxl_event_interrupt_policy *policy,
> +			bool native_cxl)
> +{
> +	struct cxl_dev_state *cxlds = &mds->cxlds;
> +	int rc;
> +
> +	if (native_cxl) {
> +		rc = cxl_event_irqsetup(mds, policy);
> +		if (rc)
> +			return rc;
> +	}
> +
> +	if (cxl_dcd_supported(mds)) {
> +		rc = cxl_event_req_irq(cxlds, policy->dcd_settings);
> +		if (rc) {
> +			dev_err(cxlds->dev, "Failed to get interrupt for DCD event log\n");
> +			cxl_disable_dcd(mds);
> +		}
> +	}
> +
> +	return 0;
> +}
> +
>  static bool cxl_event_int_is_fw(u8 setting)
>  {
>  	u8 mode = FIELD_GET(CXLDEV_EVENT_INT_MODE_MASK, setting);
> @@ -657,18 +694,26 @@ static bool cxl_event_validate_mem_policy(struct cxl_memdev_state *mds,
>  static int cxl_event_config(struct pci_host_bridge *host_bridge,
>  			    struct cxl_memdev_state *mds, bool irq_avail)
>  {
> -	struct cxl_event_interrupt_policy policy;
> +	struct cxl_event_interrupt_policy policy = { 0 };
> +	bool native_cxl = host_bridge->native_cxl_error;
>  	int rc;
>  
>  	/*
>  	 * When BIOS maintains CXL error reporting control, it will process
>  	 * event records.  Only one agent can do so.
> +	 *
> +	 * If BIOS has control of events and DCD is not supported skip event
> +	 * configuration.
>  	 */
> -	if (!host_bridge->native_cxl_error)
> +	if (!native_cxl && !cxl_dcd_supported(mds))
>  		return 0;
>  
>  	if (!irq_avail) {
>  		dev_info(mds->cxlds.dev, "No interrupt support, disable event processing.\n");
> +		if (cxl_dcd_supported(mds)) {
> +			dev_info(mds->cxlds.dev, "DCD requires interrupts, disable DCD\n");
> +			cxl_disable_dcd(mds);
> +		}
>  		return 0;
>  	}
>  
> @@ -676,10 +721,10 @@ static int cxl_event_config(struct pci_host_bridge *host_bridge,
>  	if (rc)
>  		return rc;
>  
> -	if (!cxl_event_validate_mem_policy(mds, &policy))
> +	if (native_cxl && !cxl_event_validate_mem_policy(mds, &policy))
>  		return -EBUSY;
>  
> -	rc = cxl_event_config_msgnums(mds, &policy);
> +	rc = cxl_event_config_msgnums(mds, &policy, native_cxl);
>  	if (rc)
>  		return rc;
>  
> @@ -687,12 +732,16 @@ static int cxl_event_config(struct pci_host_bridge *host_bridge,
>  	if (rc)
>  		return rc;
>  
> -	rc = cxl_event_irqsetup(mds, &policy);
> +	rc = cxl_irqsetup(mds, &policy, native_cxl);
>  	if (rc)
>  		return rc;
>  
>  	cxl_mem_get_event_records(mds, CXLDEV_EVENT_STATUS_ALL);

Issue that was always there probably, should this check native_cxl so the BIOS owned events are not retrieved?

	if (native_cxl)
		cxl_mem_get_event_records(mds, CXLDEV_EVENT_STATUS_ALL);


Also, CXLDEV_EVENT_STATUS_ALL is missing bit 4 (Dynamic Capcity Event Log). CXL r4.0 8.2.9.3.1 Table 8-203.


DJ


>  
> +	dev_dbg(mds->cxlds.dev, "Event config : %s DCD %s\n",
> +		native_cxl ? "OS" : "BIOS",
> +		cxl_dcd_supported(mds) ? "supported" : "not supported");
> +
>  	return 0;
>  }
>