github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-09-23 22:14:03 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

cxl/pci: Remove incorrect mbox.valid check in cxl_pci_type3_init_mailbox()

Browse Source 
The driver's design intent is that missing or malformed component
registers should not prevent mailbox initialization. cxl_pci_probe()
already reflects this: the CXL_REGLOC_RBI_COMPONENT setup path only
emits a dev_warn() and continues when component registers are absent,
rather than returning an error.

The check 'if (!cxlds->reg_map.device_map.mbox.valid)' violates this
intent and is also technically incorrect for two reasons:

1. Wrong struct: the MEMDEV register block is enumerated into a local
   variable 'map', not into 'cxlds->reg_map'. The device_map.mbox.valid
   field inside cxlds->reg_map is never written by the MEMDEV probe and
   will always read as zero regardless of actual hardware capability.

2. Already validated: cxl_pci_setup_regs(CXL_REGLOC_RBI_MEMDEV) calls
   cxl_probe_regs() which explicitly checks mbox.valid and returns
   -ENXIO if the mailbox is absent. If that check passes, the mailbox is
   guaranteed to be present by the time cxl_pci_type3_init_mailbox() is
   called.

The value that the check actually reads is component_map.ras.valid,
which aliases device_map.mbox.valid in the union. This is populated by
the COMPONENT probe, not the MEMDEV probe. On devices where the
component register BAR does not implement a CXL Component Capability
Array (e.g. certain DCD devices), cxl_probe_component_regs() returns
early leaving ras.valid=false. Through the union, this makes mbox.valid
read as false, causing cxl_pci_type3_init_mailbox() to return -ENODEV
(-19) even though the mailbox hardware is fully functional.

Remove the check. Mailbox presence has already been validated by
cxl_pci_setup_regs(CXL_REGLOC_RBI_MEMDEV). The presence or absence of
component registers is irrelevant to mailbox initialization.

Fixes: 8d8081cecf ("cxl: Move mailbox related bits to the same context")
Reviewed-by: Richard Cheng <icheng@nvidia.com>
Signed-off-by: Wei Hou <wei.hou@scaleflux.com>
Reviewed-by: Li Ming <ming.li@zohomail.com>
Link: https://patch.msgid.link/20260628155857.239866-1-wei.hou@scaleflux.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
This commit is contained in:
Wei Hou 2026-06-28 23:58:57 +08:00 committed by Dave Jiang
parent a667f1eb71
commit d79b81893d
1 changed files with 0 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
drivers/cxl/pci.c
View File

@ -691,12 +691,6 @@ static int cxl_pci_type3_init_mailbox(struct cxl_dev_state *cxlds)
{
int rc;
/*
* Fail the init if there's no mailbox. For a type3 this is out of spec.
*/
if (!cxlds->reg_map.device_map.mbox.valid)
return -ENODEV;
rc = cxl_mailbox_init(&cxlds->cxl_mbox, cxlds->dev);
if (rc)
return rc;