github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-07-27 09:36:22 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

cxl/region: Block region delete during region creation

Browse Source 
Expand the range lock, rename it "regions_lock", to disable region deletion
in the critical period between construct_region() and attach_target(), as
well as the period between device_add() and registering the remove actions.

Otherwise, userspace can confuse the kernel. It can violate the assumption
the region stays registered through the completion of cxl_add_to_region().
It can violate the assumption that devm_add_action_or_reset() is working
with a live 'struct cxl_region'.

It is ok for the region to disappear outside of those windows as that
mirrors device hotplug flows where the proper locks are held.

Fixes: a32320b71f ("cxl/region: Add region autodiscovery")
Signed-off-by: Dan Williams <djbw@kernel.org>
Reviewed-by: Alejandro Lucero <alucerop@amd.com>
Tested-by: ALejandro Lucero <alucerop@amd.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Link: https://patch.msgid.link/20260519210158.1499795-2-djbw@kernel.org
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
This commit is contained in:
Dan Williams 2026-05-19 14:01:54 -07:00 committed by Dave Jiang
parent e43ffb69e0
commit d91feb8869
3 changed files with 13 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/cxl/core/port.c
View File

@ -2016,7 +2016,7 @@ struct cxl_root_decoder *cxl_root_decoder_alloc(struct cxl_port *port,
return ERR_PTR(rc);
}
mutex_init(&cxlrd->range_lock);
mutex_init(&cxlrd->regions_lock);
cxld = &cxlsd->cxld;
cxld->dev.type = &cxl_decoder_root_type;

12
drivers/cxl/core/region.c
View File

@ -2779,6 +2779,10 @@ static ssize_t create_region_store(struct device *dev, const char *buf,
if (rc != 1)
return -EINVAL;
ACQUIRE(mutex_intr, regions_lock)(&cxlrd->regions_lock);
if ((rc = ACQUIRE_ERR(mutex_intr, &regions_lock)))
return rc;
cxlr = __create_region(cxlrd, mode, id, CXL_DECODER_HOSTONLYMEM);
if (IS_ERR(cxlr))
return PTR_ERR(cxlr);
@ -2838,6 +2842,11 @@ static ssize_t delete_region_store(struct device *dev,
struct cxl_root_decoder *cxlrd = to_cxl_root_decoder(dev);
struct cxl_port *port = to_cxl_port(dev->parent);
struct cxl_region *cxlr;
int rc;
ACQUIRE(mutex_intr, regions_lock)(&cxlrd->regions_lock);
if ((rc = ACQUIRE_ERR(mutex_intr, &regions_lock)))
return rc;
cxlr = cxl_find_region_by_name(cxlrd, buf);
if (IS_ERR(cxlr))
@ -3776,12 +3785,11 @@ int cxl_add_to_region(struct cxl_endpoint_decoder *cxled)
* for the HPA range, one does the construction and the others
* add to that.
*/
mutex_lock(&cxlrd->range_lock);
guard(mutex)(&cxlrd->regions_lock);
struct cxl_region *cxlr __free(put_cxl_region) =
cxl_find_region_by_range(cxlrd, &ctx.hpa_range);
if (!cxlr)
cxlr = construct_region(cxlrd, &ctx);
mutex_unlock(&cxlrd->range_lock);
rc = PTR_ERR_OR_ZERO(cxlr);
if (rc)

4
drivers/cxl/cxl.h
View File

@ -359,7 +359,7 @@ struct cxl_rd_ops {
* @cache_size: extended linear cache size if exists, otherwise zero.
* @region_id: region id for next region provisioning event
* @platform_data: platform specific configuration data
* @range_lock: sync region autodiscovery by address range
* @regions_lock: sync region discovery, construction, and deletion
* @qos_class: QoS performance class cookie
* @ops: CXL root decoder operations
* @cxlsd: base cxl switch decoder
@ -369,7 +369,7 @@ struct cxl_root_decoder {
resource_size_t cache_size;
atomic_t region_id;
void *platform_data;
struct mutex range_lock;
struct mutex regions_lock;
int qos_class;
struct cxl_rd_ops ops;
struct cxl_switch_decoder cxlsd;