On 6/25/2026 6:04 AM, Anisa Su wrote:
> From: Ira Weiny <[email protected]>
>
> 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 <[email protected]>
> Signed-off-by: Anisa Su <[email protected]>
>
> ---
> Changes:
> [anisa: add CXLDEV_EVENT_STATUS_DCD (bit 4) to CXLDEV_EVENT_STATUS_ALL;
> previously added in a later commit but moved to current commit]
>
> [anisa: check native_cxl before cxl_mem_get_event_records]
> ---
> drivers/cxl/cxl.h | 4 +-
> drivers/cxl/cxlmem.h | 2 +
> drivers/cxl/pci.c | 94 ++++++++++++++++++++++++++++++++++++--------
> 3 files changed, 83 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
> index 1297594beaec..864f6d3c03d4 100644
> --- a/drivers/cxl/cxl.h
> +++ b/drivers/cxl/cxl.h
> @@ -180,11 +180,13 @@ static inline int ways_to_eiw(unsigned int ways, u8
> *eiw)
> #define CXLDEV_EVENT_STATUS_WARN BIT(1)
> #define CXLDEV_EVENT_STATUS_FAIL BIT(2)
> #define CXLDEV_EVENT_STATUS_FATAL BIT(3)
> +#define CXLDEV_EVENT_STATUS_DCD BIT(4)
>
> #define CXLDEV_EVENT_STATUS_ALL (CXLDEV_EVENT_STATUS_INFO | \
> CXLDEV_EVENT_STATUS_WARN | \
> CXLDEV_EVENT_STATUS_FAIL | \
> - CXLDEV_EVENT_STATUS_FATAL)
> + CXLDEV_EVENT_STATUS_FATAL | \
> + CXLDEV_EVENT_STATUS_DCD)
>
> /* CXL rev 3.0 section 8.2.9.2.4; Table 8-52 */
> #define CXLDEV_EVENT_INT_MODE_MASK GENMASK(1, 0)
> diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
> index afc195d8c090..bcf976829c3e 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..95a4bf7c1e46 100644
> --- a/drivers/cxl/pci.c
> +++ b/drivers/cxl/pci.c
> @@ -514,7 +514,19 @@ static irqreturn_t cxl_event_thread(int irq, void *id)
> struct cxl_dev_id *dev_id = id;
> struct cxl_dev_state *cxlds = dev_id->cxlds;
> struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlds);
> + struct pci_host_bridge *host_bridge =
> + pci_find_host_bridge(to_pci_dev(cxlds->dev)->bus);
> u32 status;
> + u32 mask;
> +
> + /*
> + * Only drain logs the driver owns. When BIOS owns event reporting
> + * (!native_cxl) the driver is only here for the Dynamic Capacity log;
> + * processing the standard logs would steal firmware-first events from
> + * BIOS, so mask them out.
> + */
> + mask = host_bridge->native_cxl_error ? CXLDEV_EVENT_STATUS_ALL
> + : CXLDEV_EVENT_STATUS_DCD;
>
> do {
> /*
> @@ -522,8 +534,8 @@ static irqreturn_t cxl_event_thread(int irq, void *id)
> * ignore the reserved upper 32 bits
> */
> status = readl(cxlds->regs.status +
> CXLDEV_DEV_EVENT_STATUS_OFFSET);
> - /* Ignore logs unknown to the driver */
> - status &= CXLDEV_EVENT_STATUS_ALL;
> + /* Ignore logs unknown to the driver or owned by BIOS */
> + status &= mask;
> if (!status)
> break;
> cxl_mem_get_event_records(mds, status);
> @@ -557,6 +569,8 @@ 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 +583,34 @@ 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);
> + }
It seems there's a bug here that I found on one of our test machines. It's
possible the card doesn't support
DCD commands but does have the policy bit for DCD (i.e. CXL card is 3.0+), so
the payload still needs to be
large enough to include the DCD bit in that case. So, the size_in needs to
always include dcd_settings but
the actual policy setting should stay based on whether the card supports DCD.
Hopefully that makes sense, let
me know if it's not clear...
The first thing that I thought of for a solution is setting size_in based on
the CXL card's DVSEC revision
(i.e. size_in = 5 for CXL 3.0+, size_in = 4 otherwise). Not exactly a clean
solution, but I'm not sure there's
a way around it.
Thanks,
Ben
>
> 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 +657,30 @@ 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 +706,26 @@ 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 +733,10 @@ 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;
>
> @@ -687,11 +744,16 @@ 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);
> + if (native_cxl)
> + 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;
> }
