[PATCH 3/9] x86/pci: Add MCFG debug logging

Bjorn Helgaas
2023-11-21T18:37:04Z

MCFG handling is a frequent source of problems. Add more logging to aid in
debugging.

Enable the logging with CONFIG_DYNAMIC_DEBUG=y and the kernel boot
parameter 'dyndbg="file arch/x86/pci +p"'.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
---
arch/x86/pci/acpi.c | 3 +++
arch/x86/pci/mmconfig-shared.c | 23 ++++++++++++++++++-----
2 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c
index ea2eb2ec90e2..55c4b07ec1f6 100644
--- a/arch/x86/pci/acpi.c
+++ b/arch/x86/pci/acpi.c
@@ -283,6 +283,9 @@ static int setup_mcfg_map(struct acpi_pci_root_info *ci)
info->mcfg_added = false;
seg = info->sd.domain;

+ dev_dbg(dev, "%s(%04x %pR ECAM %pa)\n", __func__, seg,
+ &root->secondary, &root->mcfg_addr);
+
/* return success if MMCFG is not in use */
if (raw_pci_ext_ops && raw_pci_ext_ops != &pci_mmcfg)
return 0;
diff --git a/arch/x86/pci/mmconfig-shared.c b/arch/x86/pci/mmconfig-shared.c
index 64c39a23d37a..bc1312d920da 100644
--- a/arch/x86/pci/mmconfig-shared.c
+++ b/arch/x86/pci/mmconfig-shared.c
@@ -579,7 +579,8 @@ static void __init pci_mmcfg_reject_broken(int early)

list_for_each_entry(cfg, &pci_mmcfg_list, list) {
if (pci_mmcfg_check_reserved(NULL, cfg, early) == 0) {
- pr_info(PREFIX "not using MMCONFIG\n");
+ pr_info(PREFIX "not using MMCONFIG (%pR not reserved)\n",
+ &cfg->res);
free_all_mmcfg();
return;
}
@@ -676,6 +677,8 @@ static int pci_mmcfg_for_each_region(int (*func)(__u64 start, __u64 size,

static void __init __pci_mmcfg_init(int early)
{
+ pr_debug(PREFIX "%s(%s)\n", __func__, early ? "early" : "late");
+
pci_mmcfg_reject_broken(early);
if (list_empty(&pci_mmcfg_list))
return;
@@ -702,6 +705,8 @@ static int __initdata known_bridge;

void __init pci_mmcfg_early_init(void)
{
+ pr_debug(PREFIX "%s() pci_probe %#x\n", __func__, pci_probe);
+
if (pci_probe & PCI_PROBE_MMCONF) {
if (pci_mmcfg_check_hostbridge())
known_bridge = 1;
@@ -715,6 +720,8 @@ void __init pci_mmcfg_early_init(void)

void __init pci_mmcfg_late_init(void)
{
+ pr_debug(PREFIX "%s() pci_probe %#x\n", __func__, pci_probe);
+
/* MMCONFIG disabled */
if ((pci_probe & PCI_PROBE_MMCONF) == 0)
return;
@@ -735,6 +742,8 @@ static int __init pci_mmcfg_late_insert_resources(void)

pci_mmcfg_running_state = true;

+ pr_debug(PREFIX "%s() pci_probe %#x\n", __func__, pci_probe);
+
/* If we are not using MMCONFIG, don't insert the resources. */
if ((pci_probe & PCI_PROBE_MMCONF) == 0)
return 1;
@@ -744,9 +753,12 @@ static int __init pci_mmcfg_late_insert_resources(void)
* marked so it won't cause request errors when __request_region is
* called.
*/
- list_for_each_entry(cfg, &pci_mmcfg_list, list)
- if (!cfg->res.parent)
+ list_for_each_entry(cfg, &pci_mmcfg_list, list) {
+ if (!cfg->res.parent) {
+ pr_debug(PREFIX "%s() insert %pR\n", __func__, &cfg->res);
insert_resource(&iomem_resource, &cfg->res);
+ }
+ }

return 0;
}
@@ -766,6 +778,8 @@ int pci_mmconfig_insert(struct device *dev, u16 seg, u8 start, u8 end,
struct resource *tmp = NULL;
struct pci_mmcfg_region *cfg;

+ dev_dbg(dev, "%s(%04x [bus %02x-%02x])\n", __func__, seg, start, end);
+
if (!(pci_probe & PCI_PROBE_MMCONF) || pci_mmcfg_arch_init_failed)
return -ENODEV;

@@ -810,8 +824,7 @@ int pci_mmconfig_insert(struct device *dev, u16 seg, u8 start, u8 end,
"%s %pR\n",
&cfg->res, tmp->name, tmp);
} else if (pci_mmcfg_arch_map(cfg)) {
- dev_warn(dev, "fail to map MMCONFIG %pR.\n",
- &cfg->res);
+ dev_warn(dev, "fail to map MMCONFIG %pR\n", &cfg->res);
} else {
list_add_sorted(cfg);
dev_info(dev, "MMCONFIG at %pR (base %#lx)\n",
--
2.34.1