From 5df96161b5e89dbffadc0b9e3feea49433d5c2eb Mon Sep 17 00:00:00 2001
From: Alison Schofield <alison.schofield@intel.com>
Date: Fri, 3 Sep 2021 19:20:39 -0700
Subject: [PATCH] cxl/acpi: Do not add DSDT disabled ACPI0016 host bridge ports
Git-commit: a7bfaad54b8b9cf06041528988d6b75b4b921546
Patch-mainline: v5.15-rc1
References: stable-5.14.3
commit a7bfaad54b8b9cf06041528988d6b75b4b921546 upstream.
During CXL ACPI probe, host bridge ports are discovered by scanning
the ACPI0017 root port for ACPI0016 host bridge devices. The scan
matches on the hardware id of "ACPI0016". An issue occurs when an
ACPI0016 device is defined in the DSDT yet disabled on the platform.
Attempts by the cxl_acpi driver to add host bridge ports using a
disabled device fails, and the entire cxl_acpi probe fails.
The DSDT table includes an _STA method that sets the status and the
ACPI subsystem has checks available to examine it. One such check is
in the acpi_pci_find_root() path. Move the call to acpi_pci_find_root()
to the matching function to prevent this issue when adding either
upstream or downstream ports.
Suggested-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Alison Schofield <alison.schofield@intel.com>
Fixes: 7d4b5ca2e2cb ("cxl/acpi: Add downstream port data to cxl_port instances")
Cc: <stable@vger.kernel.org>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/163072203957.2250120.2178685721061002124.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/cxl/acpi.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
index 8ae89273f58e..54e9d4d2cf5f 100644
--- a/drivers/cxl/acpi.c
+++ b/drivers/cxl/acpi.c
@@ -243,6 +243,9 @@ static struct acpi_device *to_cxl_host_bridge(struct device *dev)
{
struct acpi_device *adev = to_acpi_device(dev);
+ if (!acpi_pci_find_root(adev->handle))
+ return NULL;
+
if (strcmp(acpi_device_hid(adev), "ACPI0016") == 0)
return adev;
return NULL;
@@ -266,10 +269,6 @@ static int add_host_bridge_uport(struct device *match, void *arg)
if (!bridge)
return 0;
- pci_root = acpi_pci_find_root(bridge->handle);
- if (!pci_root)
- return -ENXIO;
-
dport = find_dport_by_dev(root_port, match);
if (!dport) {
dev_dbg(host, "host bridge expected and not found\n");
@@ -282,6 +281,11 @@ static int add_host_bridge_uport(struct device *match, void *arg)
return PTR_ERR(port);
dev_dbg(host, "%s: add: %s\n", dev_name(match), dev_name(&port->dev));
+ /*
+ * Note that this lookup already succeeded in
+ * to_cxl_host_bridge(), so no need to check for failure here
+ */
+ pci_root = acpi_pci_find_root(bridge->handle);
ctx = (struct cxl_walk_context){
.dev = host,
.root = pci_root->bus,
--
2.26.2