Re: [PATCH 13/26] cxl/mem: Configure dynamic capacity interrupts

Dan Williams
2024-05-06T16:56:55Z

ira.weiny@ wrote:
> From: Navneet Singh <navneet.singh@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. Split irq configuration of memory events and
> DCD events to allow for FW control of memory events while DCD is host
> controlled.
>
> Configure DCD event log interrupts on devices supporting dynamic
> capacity. Disable DCD if interrupts are not supported.
>
> Signed-off-by: Navneet Singh <navneet.singh@intel.com>
> Co-developed-by: Ira Weiny <ira.weiny@intel.com>
> Signed-off-by: Ira Weiny <ira.weiny@intel.com>
>
> ---
> Changes for v1
> [iweiny: rebase to upstream irq code]
> [iweiny: disable DCD if irqs not supported]
> ---
> drivers/cxl/core/mbox.c | 9 ++++++-
> drivers/cxl/cxl.h | 4 ++-
> drivers/cxl/cxlmem.h | 4 +++
> drivers/cxl/pci.c | 71 ++++++++++++++++++++++++++++++++++++++++---------
> 4 files changed, 74 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
> index 14e8a7528a8b..58b31fa47b93 100644
> --- a/drivers/cxl/core/mbox.c
> +++ b/drivers/cxl/core/mbox.c
> @@ -1323,10 +1323,17 @@ static int cxl_get_dc_config(struct cxl_memdev_state *mds, u8 start_region,
> return rc;
> }
>
> -static bool cxl_dcd_supported(struct cxl_memdev_state *mds)
> +bool cxl_dcd_supported(struct cxl_memdev_state *mds)
> {
> return test_bit(CXL_DCD_ENABLED_GET_CONFIG, mds->dcd_cmds);
> }
> +EXPORT_SYMBOL_NS_GPL(cxl_dcd_supported, CXL);
> +
> +void cxl_disable_dcd(struct cxl_memdev_state *mds)
> +{
> + clear_bit(CXL_DCD_ENABLED_GET_CONFIG, mds->dcd_cmds);
> +}
> +EXPORT_SYMBOL_NS_GPL(cxl_disable_dcd, CXL);

Just use the open-coded bit ops, or local / static helpers because these
helpers do not consume any other infra from core/mbox.c.

> /**
> * cxl_dev_dynamic_capacity_identify() - Reads the dynamic capacity
> diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
> index 15d418b3bc9b..d585f5fdd3ae 100644
> --- a/drivers/cxl/cxl.h
> +++ b/drivers/cxl/cxl.h
> @@ -164,11 +164,13 @@ 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 4624cf612c1e..01bee6eedff3 100644
> --- a/drivers/cxl/cxlmem.h
> +++ b/drivers/cxl/cxlmem.h
> @@ -225,7 +225,9 @@ 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
> @@ -890,6 +892,8 @@ void cxl_event_trace_record(const struct cxl_memdev *cxlmd,
> enum cxl_event_log_type type,
> enum cxl_event_type event_type,
> const uuid_t *uuid, union cxl_event *evt);
> +bool cxl_dcd_supported(struct cxl_memdev_state *mds);
> +void cxl_disable_dcd(struct cxl_memdev_state *mds);
> int cxl_set_timestamp(struct cxl_memdev_state *mds);
> int cxl_poison_state_init(struct cxl_memdev_state *mds);
> int cxl_mem_get_poison(struct cxl_memdev *cxlmd, u64 offset, u64 len,
> diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
> index 12cd5d399230..ef482eae09e9 100644
> --- a/drivers/cxl/pci.c
> +++ b/drivers/cxl/pci.c
> @@ -669,22 +669,33 @@ 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_mbox_cmd mbox_cmd;
> + size_t size_in;
> 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,
> - };
> + 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,

No need to initialize dcd_settings.

> + };
> + }
> + size_in = CXL_EVENT_INT_POLICY_BASE_SIZE;

Let's skip adding this new #define and make it explicit, i.e. wihtout
needing to crack open the spec, that the dcd settings are incremental to
the original payload size:

size_in = offsetof(typeof(*policy), dcd_settings);

> +
> + if (cxl_dcd_supported(mds)) {
> + policy->dcd_settings = CXL_INT_MSI_MSIX;
> + size_in += sizeof(policy->dcd_settings);

...and then this can just be:

size_in = sizeof(*policy);

> + }
>
> 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(mds, &mbox_cmd);
> @@ -731,6 +742,31 @@ 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;
> + }
> + }

I think this could be simplified if cxl_event_req_irq() simply skipped
the non CXL_INT_MSI_MSIX modes. I.e. cxl_event_req_irq() is being too
strict after the policy settings have already run the gauntlet.