linux-kernel - Re: [PATCH RFC v2 02/18] cxl/mbox: Flag support for Dynamic Capacity Devices (DCD)

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Message-ID: <20231024171631.000066c7@Huawei.com>
Date:   Tue, 24 Oct 2023 17:16:31 +0100
From:   Jonathan Cameron <Jonathan.Cameron@...wei.com>
To:     Ira Weiny <ira.weiny@...el.com>
CC:     Dan Williams <dan.j.williams@...el.com>,
        Navneet Singh <navneet.singh@...el.com>,
        Fan Ni <fan.ni@...sung.com>,
        Davidlohr Bueso <dave@...olabs.net>,
        Dave Jiang <dave.jiang@...el.com>,
        Alison Schofield <alison.schofield@...el.com>,
        Vishal Verma <vishal.l.verma@...el.com>,
        <linux-cxl@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RFC v2 02/18] cxl/mbox: Flag support for Dynamic
 Capacity Devices (DCD)

On Mon, 28 Aug 2023 22:20:53 -0700
Ira Weiny <ira.weiny@...el.com> wrote:

> Per the CXL 3.0 specification software must check the Command Effects
> Log (CEL) to know if a device supports DC.  If the device does support
> DC the specifics of the DC Regions (0-7) are read through the mailbox.
> 
> Flag DC Device (DCD) commands in a device if they are supported.
> Subsequent patches will key off these bits to configure a DCD.
> 
> Co-developed-by: Navneet Singh <navneet.singh@...el.com>
> Signed-off-by: Navneet Singh <navneet.singh@...el.com>
> Signed-off-by: Ira Weiny <ira.weiny@...el.com>
> 
> ---
> Changes for v2
> [iweiny: new patch]
> ---
>  drivers/cxl/core/mbox.c | 38 +++++++++++++++++++++++++++++++++++---
>  drivers/cxl/cxlmem.h    | 15 +++++++++++++++
>  2 files changed, 50 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
> index f052d5f174ee..554ec97a7c39 100644
> --- a/drivers/cxl/core/mbox.c
> +++ b/drivers/cxl/core/mbox.c
> @@ -111,6 +111,34 @@ static u8 security_command_sets[] = {
>  	0x46, /* Security Passthrough */
>  };
>  
Small note I noticed whilst rebasing this for some tests.
Adding this in the middle of the stuff for security commands is
a bit odd. I'd move it up or down a few lines.

> +static bool cxl_is_dcd_command(u16 opcode)
> +{
> +#define CXL_MBOX_OP_DCD_CMDS 0x48
> +
> +	return (opcode >> 8) == CXL_MBOX_OP_DCD_CMDS;
> +}
> +
> +static void cxl_set_dcd_cmd_enabled(struct cxl_memdev_state *mds,
> +					u16 opcode)
> +{
> +	switch (opcode) {
> +	case CXL_MBOX_OP_GET_DC_CONFIG:
> +		set_bit(CXL_DCD_ENABLED_GET_CONFIG, mds->dcd_cmds);
> +		break;
> +	case CXL_MBOX_OP_GET_DC_EXTENT_LIST:
> +		set_bit(CXL_DCD_ENABLED_GET_EXTENT_LIST, mds->dcd_cmds);
> +		break;
> +	case CXL_MBOX_OP_ADD_DC_RESPONSE:
> +		set_bit(CXL_DCD_ENABLED_ADD_RESPONSE, mds->dcd_cmds);
> +		break;
> +	case CXL_MBOX_OP_RELEASE_DC:
> +		set_bit(CXL_DCD_ENABLED_RELEASE, mds->dcd_cmds);
> +		break;
> +	default:
> +		break;
> +	}
> +}
> +
>  static bool cxl_is_security_command(u16 opcode)
>  {
>  	int i;
> @@ -677,9 +705,10 @@ static void cxl_walk_cel(struct cxl_memdev_state *mds, size_t size, u8 *cel)
>  		u16 opcode = le16_to_cpu(cel_entry[i].opcode);
>  		struct cxl_mem_command *cmd = cxl_mem_find_command(opcode);
>  
> -		if (!cmd && !cxl_is_poison_command(opcode)) {
> -			dev_dbg(dev,
> -				"Opcode 0x%04x unsupported by driver\n", opcode);
> +		if (!cmd && !cxl_is_poison_command(opcode) &&
> +		    !cxl_is_dcd_command(opcode)) {
> +			dev_dbg(dev, "Opcode 0x%04x unsupported by driver\n",
> +				opcode);
>  			continue;
>  		}
>  
> @@ -689,6 +718,9 @@ static void cxl_walk_cel(struct cxl_memdev_state *mds, size_t size, u8 *cel)
>  		if (cxl_is_poison_command(opcode))
>  			cxl_set_poison_cmd_enabled(&mds->poison, opcode);
>  
> +		if (cxl_is_dcd_command(opcode))
> +			cxl_set_dcd_cmd_enabled(mds, opcode);
> +
>  		dev_dbg(dev, "Opcode 0x%04x enabled\n", opcode);
>  	}
>  }
> diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
> index adfba72445fc..5f2e65204bf9 100644
> --- a/drivers/cxl/cxlmem.h
> +++ b/drivers/cxl/cxlmem.h
> @@ -247,6 +247,15 @@ struct cxl_event_state {
>  	struct mutex log_lock;
>  };
>  
> +/* Device enabled DCD commands */
> +enum dcd_cmd_enabled_bits {
> +	CXL_DCD_ENABLED_GET_CONFIG,
> +	CXL_DCD_ENABLED_GET_EXTENT_LIST,
> +	CXL_DCD_ENABLED_ADD_RESPONSE,
> +	CXL_DCD_ENABLED_RELEASE,
> +	CXL_DCD_ENABLED_MAX
> +};
> +
>  /* Device enabled poison commands */
>  enum poison_cmd_enabled_bits {
>  	CXL_POISON_ENABLED_LIST,
> @@ -436,6 +445,7 @@ struct cxl_dev_state {
>   *                (CXL 2.0 8.2.9.5.1.1 Identify Memory Device)
>   * @mbox_mutex: Mutex to synchronize mailbox access.
>   * @firmware_version: Firmware version for the memory device.
> + * @dcd_cmds: List of DCD commands implemented by memory device
>   * @enabled_cmds: Hardware commands found enabled in CEL.
>   * @exclusive_cmds: Commands that are kernel-internal only
>   * @total_bytes: sum of all possible capacities
> @@ -460,6 +470,7 @@ struct cxl_memdev_state {
>  	size_t lsa_size;
>  	struct mutex mbox_mutex; /* Protects device mailbox and firmware */
>  	char firmware_version[0x10];
> +	DECLARE_BITMAP(dcd_cmds, CXL_DCD_ENABLED_MAX);
>  	DECLARE_BITMAP(enabled_cmds, CXL_MEM_COMMAND_ID_MAX);
>  	DECLARE_BITMAP(exclusive_cmds, CXL_MEM_COMMAND_ID_MAX);
>  	u64 total_bytes;
> @@ -525,6 +536,10 @@ enum cxl_opcode {
>  	CXL_MBOX_OP_UNLOCK		= 0x4503,
>  	CXL_MBOX_OP_FREEZE_SECURITY	= 0x4504,
>  	CXL_MBOX_OP_PASSPHRASE_SECURE_ERASE	= 0x4505,
> +	CXL_MBOX_OP_GET_DC_CONFIG	= 0x4800,
> +	CXL_MBOX_OP_GET_DC_EXTENT_LIST	= 0x4801,
> +	CXL_MBOX_OP_ADD_DC_RESPONSE	= 0x4802,
> +	CXL_MBOX_OP_RELEASE_DC		= 0x4803,
>  	CXL_MBOX_OP_MAX			= 0x10000
>  };
>  
>