On Thu, 2022-11-03 at 17:30 -0700, Dan Williams wrote:
> Some regions may not have any address space allocated. Skip them when
> validating HPA order otherwise a crash like the following may result:
>
> devm_cxl_add_region: cxl_acpi cxl_acpi.0: decoder3.4: created
> region9
> BUG: kernel NULL pointer dereference, address: 0000000000000000
> [..]
> RIP: 0010:store_targetN+0x655/0x1740 [cxl_core]
> [..]
> Call Trace:
> <TASK>
> kernfs_fop_write_iter+0x144/0x200
> vfs_write+0x24a/0x4d0
> ksys_write+0x69/0xf0
> do_syscall_64+0x3a/0x90
>
> store_targetN+0x655/0x1740:
> alloc_region_ref at drivers/cxl/core/region.c:676
> (inlined by) cxl_port_attach_region at drivers/cxl/core/region.c:850
> (inlined by) cxl_region_attach at drivers/cxl/core/region.c:1290
> (inlined by) attach_target at drivers/cxl/core/region.c:1410
> (inlined by) store_targetN at drivers/cxl/core/region.c:1453
>
> Cc: <stable@xxxxxxxxxxxxxxx>
> Fixes: 384e624bb211 ("cxl/region: Attach endpoint decoders")
> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
> ---
> drivers/cxl/core/region.c | 3 +++
> 1 file changed, 3 insertions(+)
Makes sense,
Reviewed-by: Vishal Verma <vishal.l.verma@xxxxxxxxx>
>
> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index bb6f4fc84a3f..d26ca7a6beae 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -658,6 +658,9 @@ static struct cxl_region_ref
> *alloc_region_ref(struct cxl_port *port,
> xa_for_each(&port->regions, index, iter) {
> struct cxl_region_params *ip = &iter->region->params;
>
> + if (!ip->res)
> + continue;
> +
> if (ip->res->start > p->res->start) {
> dev_dbg(&cxlr->dev,
> "%s: HPA order violation %s:%pr vs
> %pr\n",
>
