Re: [PATCH v4] cxl/pci: Support Global Persistent Flush (GPF)

[Dan Williams <dan.j.williams@intel.com>]

Davidlohr Bueso wrote:
> Add support for GPF flows. It is found that the CXL specification
> around this to be a bit too involved from the driver side. And while
> this should really all handled by the hardware, this patch takes
> things with a grain of salt.
> 
> Upon respective port enumeration, both phase timeouts are set to
> a max of 20 seconds, which is the NMI watchdog default for lockup
> detection. The premise is that the kernel does not have enough
> information to set anything better than a max across the board
> and hope devices finish their GPF flows within the platform energy
> budget.
> 
> Timeout detection is based on dirty Shutdown semantics. The driver
> will mark it as dirty, expecting that the device clear it upon a
> successful GPF event. The admin may consult the device Health and
> check the dirty shutdown counter to see if there was a problem
> with data integrity.
> 
> Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
> ---
> 
> Changes from v3:
>   - no rch checking (Dan)
>   - cache port dvsec (Dan)
>   - set dirty shutdown in pcxl_nvdimm_probe() (Dan)
> 
>  Documentation/driver-api/cxl/maturity-map.rst |  2 +-
>  drivers/cxl/core/core.h                       |  2 +
>  drivers/cxl/core/mbox.c                       | 18 ++++
>  drivers/cxl/core/pci.c                        | 86 +++++++++++++++++++
>  drivers/cxl/core/port.c                       |  2 +
>  drivers/cxl/cxl.h                             |  2 +
>  drivers/cxl/cxlmem.h                          |  5 ++
>  drivers/cxl/cxlpci.h                          |  6 ++
>  drivers/cxl/pmem.c                            |  8 ++
>  9 files changed, 130 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/driver-api/cxl/maturity-map.rst b/Documentation/driver-api/cxl/maturity-map.rst
> index df8e2ac2a320..99dd2c841e69 100644
> --- a/Documentation/driver-api/cxl/maturity-map.rst
> +++ b/Documentation/driver-api/cxl/maturity-map.rst
> @@ -130,7 +130,7 @@ Mailbox commands
>  * [0] Switch CCI
>  * [3] Timestamp
>  * [1] PMEM labels
> -* [0] PMEM GPF / Dirty Shutdown
> +* [1] PMEM GPF / Dirty Shutdown

Hooray!

Reviewed-by: Dan Williams <dan.j.williams@intel.com>

>  * [0] Scan Media
>  
>  PMU
> diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
> index 800466f96a68..8f2eb76a3c8c 100644
> --- a/drivers/cxl/core/core.h
> +++ b/drivers/cxl/core/core.h
> @@ -115,4 +115,6 @@ bool cxl_need_node_perf_attrs_update(int nid);
>  int cxl_port_get_switch_dport_bandwidth(struct cxl_port *port,
>  					struct access_coordinate *c);
>  
> +int cxl_gpf_port_setup(struct device *dport_dev, struct cxl_port *port);
> +
>  #endif /* __CXL_CORE_H__ */
> diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
> index 548564c770c0..5b89ae5c5e28 100644
> --- a/drivers/cxl/core/mbox.c
> +++ b/drivers/cxl/core/mbox.c
> @@ -1308,6 +1308,24 @@ int cxl_mem_create_range_info(struct cxl_memdev_state *mds)
>  }
>  EXPORT_SYMBOL_NS_GPL(cxl_mem_create_range_info, "CXL");
>  
> +int cxl_dirty_shutdown_state(struct cxl_memdev_state *mds)
> +{
> +	struct cxl_mailbox *cxl_mbox = &mds->cxlds.cxl_mbox;

In the future I want to cleanup all these functions that take @mds just
to get back to the mailbox to just take the mailbox directly, but again
that's future work.