linux-kernel - Re: [RFC PATCH 14/14] WIP/cxl/mem: Add get firmware for testing

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Date:   Wed, 9 Dec 2020 16:42:26 -0800
From:   Dan Williams <dan.j.williams@...el.com>
To:     Ben Widawsky <ben.widawsky@...el.com>
Cc:     linux-cxl@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux PCI <linux-pci@...r.kernel.org>,
        Linux ACPI <linux-acpi@...r.kernel.org>,
        Ira Weiny <ira.weiny@...el.com>,
        Vishal Verma <vishal.l.verma@...el.com>,
        "Kelley, Sean V" <sean.v.kelley@...el.com>,
        Rafael Wysocki <rafael.j.wysocki@...el.com>,
        Bjorn Helgaas <helgaas@...nel.org>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        Jon Masters <jcm@...masters.org>,
        Chris Browy <cbrowy@...ry-design.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Christoph Hellwig <hch@...radead.org>
Subject: Re: [RFC PATCH 14/14] WIP/cxl/mem: Add get firmware for testing

On Tue, Dec 8, 2020 at 4:25 PM Ben Widawsky <ben.widawsky@...el.com> wrote:
>
> This also serves as an example how to add a new command
>
> Signed-off-by: Ben Widawsky <ben.widawsky@...el.com>
> ---
>  drivers/cxl/mem.c            | 22 ++++++++++++++++++++++
>  include/uapi/linux/cxl_mem.h |  3 ++-
>  2 files changed, 24 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c
> index 6b2f8d3776b5..76aa1e6e4117 100644
> --- a/drivers/cxl/mem.c
> +++ b/drivers/cxl/mem.c
> @@ -116,6 +116,7 @@ struct cxl_mem_command {
>  static struct cxl_mem_command mem_commands[] = {
>         CXL_CMD(INVALID, NONE, 0, 0, "Reserved", false, 0),
>         CXL_CMD(RAW, TAINT, ~0, ~0, "Raw", true, 0),
> +       CXL_CMD(GET_FW_INFO, NONE, 0, 0x50, "Get FW Info", false, 0x0200),

I think CXL_CMD() arguments can be put on a diet if the
mem-command-id-to-name was moved to its own table, and the opcode was
defined as something like:

#define CXL_MBOX_OP_GET_FW_INFO 0x200

...so that CXL_CMD can just do:

    .opcode = CXL_MBOX_OP_##_id

That @_enable arg wants a flag #define like CMD_ENABLE which reads
better than 'true'. I would then add CMD_KERNEL_EXCL alongside that
flag to indicate the commands that may be exclusive to the kernel when
the device is active in a PMEM memory region, or ones that have an
alternate ABI wrapped around them like the keys subsystem for security
or the firwmare activation sysfs interface.

>  };
>
>  static int cxl_mem_wait_for_doorbell(struct cxl_mem *cxlm)
> @@ -827,6 +828,23 @@ static int cxl_mem_add_memdev(struct cxl_mem *cxlm)
>         return cxl_register(dev);
>  }
>
> +static int cxl_mem_enable_commands(struct cxl_mem *cxlm)
> +{
> +       struct cxl_mem_command *c;
> +
> +       /*
> +        * For now we pretend Get FW info is supported.
> +        *
> +        * FIXME: Invoke GET LOG to get the Command Effect Logs (CEL).
> +        */
> +       c = cxl_mem_find_command(0x200);
> +       if (!c)
> +               return -ENOENT;
> +
> +       c->enable = true;
> +       return 0;
> +}
> +
>  /**
>   * cxl_mem_identify() - Send the IDENTIFY command to the device.
>   * @cxlm: The device to identify.
> @@ -936,6 +954,10 @@ static int cxl_mem_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>         if (rc)
>                 return rc;
>
> +       rc = cxl_mem_enable_commands(cxlm);
> +       if (rc)
> +               return rc;
> +
>         rc = cxl_mem_identify(cxlm);
>         if (rc)
>                 return rc;
> diff --git a/include/uapi/linux/cxl_mem.h b/include/uapi/linux/cxl_mem.h
> index f2fbb0dcda06..3ac39acf8fa7 100644
> --- a/include/uapi/linux/cxl_mem.h
> +++ b/include/uapi/linux/cxl_mem.h
> @@ -50,7 +50,8 @@ struct cxl_command_info {
>         __u32 id;
>  #define CXL_MEM_COMMAND_ID_INVALID 0
>  #define CXL_MEM_COMMAND_ID_RAW 1
> -#define CXL_MEM_COMMAND_ID_MAX (CXL_MEM_COMMAND_ID_RAW + 1)
> +#define CXL_MEM_COMMAND_ID_GET_FW_INFO 2
> +#define CXL_MEM_COMMAND_ID_MAX (CXL_MEM_COMMAND_ID_GET_FW_INFO + 1)

Seems like CXL_MEM_COMMAND_ID definitions want to be an enum so that
CXL_MEM_COMMAND_ID_MAX does not need to be touched every time.

>
>         __u32 flags;
>  #define CXL_MEM_COMMAND_FLAG_NONE 0
> --
> 2.29.2
>