Re: [PATCH 01/26] cxl/mbox: Flag support for Dynamic Capacity Devices (DCD)

Alison Schofield
2024-04-10T18:15:34Z

On Sun, Mar 24, 2024 at 04:18:04PM -0700, Ira Weiny wrote:
> From: Navneet Singh <navneet.singh@intel.com>
>
> Per the CXL 3.1 specification software must check the Command Effects
> Log (CEL) to know if a device supports dynamic capacity (DC). If the
> device does support DC the specifics of the DC Regions (0-7) are read
> through the mailbox.

Do I need to know this 'If the device...' piece to understand this
patch? I like that below you say 'Subsequent patches will...'
That seems enough to set the scene.

>
> Flag DC Device (DCD) commands in a device if they are supported.
Why be vague w 'Flag'. How about 'Add a bitmap of DCD enabled
commands to the driver device state structure.'

> Subsequent patches will key off these bits to configure DCD.
>
> 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: update to latest master]
> [iweiny: update commit message]
> [iweiny: Based on the fix:
> https://lore.kernel.org/all/20230903-cxl-cel-fix-v1-1-e260c9467be3@intel.com/
> [jonathan: remove unneeded format change]
> [jonathan: don't split security code in mbox.c]
> ---
> drivers/cxl/core/mbox.c | 33 +++++++++++++++++++++++++++++++++
> drivers/cxl/cxlmem.h | 15 +++++++++++++++
> 2 files changed, 48 insertions(+)
>

snip

> /* Device enabled poison commands */
> enum poison_cmd_enabled_bits {
> CXL_POISON_ENABLED_LIST,
> @@ -454,6 +463,7 @@ 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

It's not a 'List' it's a bitmap. How about mimicing 'enabled_cmds'
description:

* @dcd_cmds: DCD commands found enabled in CEL

> * @total_bytes: sum of all possible capacities
> @@ -481,6 +491,7 @@ 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;
> @@ -551,6 +562,10 @@ 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
> };
>
>
> --
> 2.44.0
>