| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <d612aaee-6bf4-4a30-aef2-46619cec379c@amd.com>
Date: Mon, 12 Jan 2026 15:11:00 -0600
From: "Cheatham, Benjamin" <benjamin.cheatham@....com>
To: Gregory Price <gourry@...rry.net>, <linux-cxl@...r.kernel.org>
CC: <linux-kernel@...r.kernel.org>, <kernel-team@...a.com>,
<dave@...olabs.net>, <jonathan.cameron@...wei.com>, <dave.jiang@...el.com>,
<alison.schofield@...el.com>, <vishal.l.verma@...el.com>,
<ira.weiny@...el.com>, <dan.j.williams@...el.com>
Subject: Re: [PATCH 5/6] cxl: add CXL_REGION_SYSRAM_DEFAULT_* build options
On 1/12/2026 10:35 AM, Gregory Price wrote:
> DEFAULT_OFFLINE: Blocks will be offline after being created.
> DEFAULT_ONLINE: Blocks will be onlined in ZONE_MOVABLE
> DEFAULT_ONLINE_NORMAL: Blocks will be onliend in ZONE_NORMAL.
>
> This prevents users from having to use the MHP auto-online build config,
> which may cause misbehaviors with other devices hotplugging memory.
Isn't the MHP auto-online build config still used in some flows? A quick note on
when that option will still be used would be nice.
>
> Signed-off-by: Gregory Price <gourry@...rry.net>
> ---
> drivers/cxl/Kconfig | 40 ++++++++++
> drivers/cxl/core/memctrl/sysram_region.c | 94 ++++++++++++++++++------
> 2 files changed, 110 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/cxl/Kconfig b/drivers/cxl/Kconfig
> index 5aed1524f8f1..3e087c9d5ea7 100644
> --- a/drivers/cxl/Kconfig
> +++ b/drivers/cxl/Kconfig
> @@ -243,6 +243,46 @@ config CXL_REGION_CTRL_AUTO_SYSRAM
>
> endchoice
>
> +choice
> + prompt "CXL SYSRAM Auto Online Mode"
> + depends on CXL_REGION
> + default CXL_REGION_SYSRAM_DEFAULT_OFFLINE
> + help
> + Select whether CXL memory hotplugged as System RAM should be
> + automatically onlined and in which zone. This applies when the
> + region controller is set to SYSRAM (either explicitly or via
> + the auto control mode).
> +
> +config CXL_REGION_SYSRAM_DEFAULT_OFFLINE
> + bool "Offline"
> + help
> + Leave the memory offline after hotplug. The memory must be
> + manually onlined via sysfs or other mechanisms before it can
> + be used by the system.
> +
> + This is the default and most conservative option.
> +
> +config CXL_REGION_SYSRAM_DEFAULT_ONLINE
> + bool "Online (Movable)"
> + help
> + Automatically online the memory as ZONE_MOVABLE after hotplug.
> + ZONE_MOVABLE memory can be used for user pages and is eligible
> + for memory hotremove, but cannot be used for kernel allocations.
> +
> + Select this for memory that may need to be hotremoved later.
> +
> +config CXL_REGION_SYSRAM_DEFAULT_ONLINE_NORMAL
> + bool "Online (Normal)"
> + help
> + Automatically online the memory as ZONE_NORMAL after hotplug.
> + ZONE_NORMAL memory can be used for all allocations including
> + kernel allocations, but may not be hotremovable.
> +
> + Select this for maximum memory utilization when hotremove is
> + not required.
> +
> +endchoice
> +
> config CXL_REGION_INVALIDATION_TEST
> bool "CXL: Region Cache Management Bypass (TEST)"
> depends on CXL_REGION
> diff --git a/drivers/cxl/core/memctrl/sysram_region.c b/drivers/cxl/core/memctrl/sysram_region.c
> index a7570c8a54e1..2e2d9b59a725 100644
> --- a/drivers/cxl/core/memctrl/sysram_region.c
> +++ b/drivers/cxl/core/memctrl/sysram_region.c
> @@ -129,12 +129,69 @@ static int offline_memory_block_cb(struct memory_block *mem, void *arg)
> return *rc;
> }
>
> +static int cxl_sysram_online_memory(struct range *range, int online_type)
> +{
> + struct online_memory_cb_arg cb_arg = {
> + .online_type = online_type,
> + .rc = 0,
> + };
> + int rc;
> +
> + rc = walk_memory_blocks(range->start, range_len(range),
> + &cb_arg, online_memory_block_cb);
> + if (!rc)
> + rc = cb_arg.rc;
> +
> + return rc;
> +}
> +
> +static int cxl_sysram_offline_memory(struct range *range)
> +{
> + int offline_rc = 0;
> + int rc;
> +
> + rc = walk_memory_blocks(range->start, range_len(range),
> + &offline_rc, offline_memory_block_cb);
> + if (!rc)
> + rc = offline_rc;
> +
> + return rc;
> +}
I think these two helpers can get moved into patch 2/6 when the 'store' attribute was defined. I don't
see anything that requires they're in this patch and it would help reduce churn.
> +
> +static int cxl_sysram_auto_online(struct device *dev, struct range *range)
> +{
> + int online_type;
> + int rc;
> +
> + if (IS_ENABLED(CONFIG_CXL_REGION_SYSRAM_DEFAULT_OFFLINE))
> + return 0;
> +
> + if (IS_ENABLED(CONFIG_CXL_REGION_SYSRAM_DEFAULT_ONLINE))
> + online_type = MMOP_ONLINE_MOVABLE;
> + else if (IS_ENABLED(CONFIG_CXL_REGION_SYSRAM_DEFAULT_ONLINE_NORMAL))
> + online_type = MMOP_ONLINE_KERNEL;
> + else
> + online_type = MMOP_ONLINE_MOVABLE;
> +
> + rc = lock_device_hotplug_sysfs();
> + if (rc)
> + return rc;
> +
> + rc = cxl_sysram_online_memory(range, online_type);
> +
> + unlock_device_hotplug();
> +
> + if (rc)
> + dev_warn(dev, "auto-online failed: %d\n", rc);
> +
> + return rc;
> +}
> +
> static ssize_t state_store(struct device *dev,
> struct device_attribute *attr,
> const char *buf, size_t len)
> {
> struct cxl_region *cxlr = to_cxl_region(dev);
> - struct online_memory_cb_arg cb_arg;
> struct range range;
> int rc;
>
> @@ -149,30 +206,14 @@ static ssize_t state_store(struct device *dev,
> if (rc)
> return rc;
>
> - if (sysfs_streq(buf, "online")) {
> - cb_arg.online_type = MMOP_ONLINE_MOVABLE;
> - cb_arg.rc = 0;
> - rc = walk_memory_blocks(range.start, range_len(&range),
> - &cb_arg, online_memory_block_cb);
> - if (!rc)
> - rc = cb_arg.rc;
> - } else if (sysfs_streq(buf, "online_normal")) {
> - cb_arg.online_type = MMOP_ONLINE;
> - cb_arg.rc = 0;
> - rc = walk_memory_blocks(range.start, range_len(&range),
> - &cb_arg, online_memory_block_cb);
> - if (!rc)
> - rc = cb_arg.rc;
> - } else if (sysfs_streq(buf, "offline")) {
> - int offline_rc = 0;
> -
> - rc = walk_memory_blocks(range.start, range_len(&range),
> - &offline_rc, offline_memory_block_cb);
> - if (!rc)
> - rc = offline_rc;
> - } else {
> + if (sysfs_streq(buf, "online"))
> + rc = cxl_sysram_online_memory(&range, MMOP_ONLINE_MOVABLE);
> + else if (sysfs_streq(buf, "online_normal"))
> + rc = cxl_sysram_online_memory(&range, MMOP_ONLINE);
> + else if (sysfs_streq(buf, "offline"))
> + rc = cxl_sysram_offline_memory(&range);
> + else
> rc = -EINVAL;
> - }
>
> unlock_device_hotplug();
>
> @@ -332,6 +373,10 @@ int devm_cxl_add_sysram_region(struct cxl_region *cxlr)
> dev_dbg(dev, "%s: added %llu bytes as System RAM\n", dev_name(dev),
> (unsigned long long)total_len);
>
> + rc = cxl_sysram_auto_online(dev, &range);
> + if (rc)
> + goto err_auto_online;
> +
> dev_set_drvdata(dev, data);
> rc = devm_device_add_group(dev, &cxl_sysram_region_group);
> if (rc)
> @@ -341,6 +386,7 @@ int devm_cxl_add_sysram_region(struct cxl_region *cxlr)
>
> err_add_group:
> dev_set_drvdata(dev, NULL);
> +err_auto_online:
> /* if this fails, memory cannot be removed from the system until reboot */
> remove_memory(range.start, range_len(&range));
> err_add_memory:
Powered by blists - more mailing lists