Re: [PATCH v4 19/28] cxl/mem: Configure dynamic capacity interrupts

[Fan Ni]

On Mon, Oct 07, 2024 at 06:16:25PM -0500, ira.weiny@xxxxxxxxx wrote:
> From: Navneet Singh <navneet.singh@xxxxxxxxx>
> 
> 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.
> 
> Signed-off-by: Navneet Singh <navneet.singh@xxxxxxxxx>
> Co-developed-by: Ira Weiny <ira.weiny@xxxxxxxxx>
> Signed-off-by: Ira Weiny <ira.weiny@xxxxxxxxx>
> 
> ---
> Changes:
> [iweiny: rebase on 6.12]
> ---
>  drivers/cxl/cxlmem.h |  2 ++
>  drivers/cxl/pci.c    | 72 +++++++++++++++++++++++++++++++++++++++++++---------
>  2 files changed, 62 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
> index c3b889a586d8..2d2a1884a174 100644
> --- a/drivers/cxl/cxlmem.h
> +++ b/drivers/cxl/cxlmem.h
> @@ -226,7 +226,9 @@ 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 c6042db0653d..2ba059d313c2 100644
> --- a/drivers/cxl/pci.c
> +++ b/drivers/cxl/pci.c
> @@ -672,23 +672,34 @@ 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);
> @@ -735,6 +746,31 @@ 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 rc;

If the device has both static and dynamic capacity, return an error code
here will cause cxl_event_config() return early, and
cxl_mem_get_event_records() will not be called, will it be an issue?

Fan

> +		}
> +	}
> +
> +	return 0;
> +}
> +
>  static bool cxl_event_int_is_fw(u8 setting)
>  {
>  	u8 mode = FIELD_GET(CXLDEV_EVENT_INT_MODE_MASK, setting);
> @@ -761,17 +797,25 @@ 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 = { 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;
>  	}
>  
> @@ -779,10 +823,10 @@ 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;
>  
> @@ -790,12 +834,16 @@ 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);
>  
> +	dev_dbg(mds->cxlds.dev, "Event config : %s DCD %s\n",
> +		native_cxl ? "OS" : "BIOS",
> +		cxl_dcd_supported(mds) ? "supported" : "not supported");
> +
>  	return 0;
>  }
>  
> 
> -- 
> 2.46.0
> 

-- 
Fan Ni