Re: [PATCH v6 07/16] x86/pci: Add Hygon Dhyana support to PCI and north bridge

[Pu Wen]

On 2018/9/20 1:20, Lendacky, Thomas wrote:

@@ -197,12 +212,25 @@ int amd_cache_northbridges(void)
        u16 i = 0;
        struct amd_northbridge *nb;
        struct pci_dev *root, *misc, *link;
+       const struct pci_device_id *root_ids = NULL;
+       const struct pci_device_id *misc_ids = NULL;
+       const struct pci_device_id *link_ids = NULL;
+
+       if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {
+               root_ids = amd_root_ids;
+               misc_ids = amd_nb_misc_ids;
+               link_ids = amd_nb_link_ids;
+       } else if (boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) {
+               root_ids = hygon_root_ids;
+               misc_ids = hygon_nb_misc_ids;
+               link_ids = hygon_nb_link_ids;
+       }

To be compatible with "before this patch" you should probably do:

        if (boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) {
                root_ids = hygon_root_ids;
                misc_ids = hygon_nb_misc_ids;
                link_ids = hygon_nb_link_ids;
        } else {
                root_ids = amd_root_ids;
                misc_ids = amd_nb_misc_ids;
                link_ids = amd_nb_link_ids;
        }

That way they are always the AMD values if not your chip.

...

@@ -263,9 +291,15 @@ bool __init early_is_amd_nb(u32 device)
  {
        const struct pci_device_id *id;
        u32 vendor = device & 0xffff;
+       const struct pci_device_id *misc_ids = NULL;
+
+       if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)
+               misc_ids = amd_nb_misc_ids;
+       else if (boot_cpu_data.x86_vendor == X86_VENDOR_HYGON)
+               misc_ids = hygon_nb_misc_ids;

Same comment as above.  This will probably eliminate the PANIC that
that was reported by LKP.

Yes, it's this modification that caused the PANIC reported by LKP.
Because the misc_ids will be NULL if running on Intel chip.

If change the vendor checking like this:

+       if (boot_cpu_data.x86_vendor == X86_VENDOR_HYGON)
+               misc_ids = hygon_nb_misc_ids;
+       else
+               misc_ids = amd_nb_misc_ids;

The PANIC will be eliminated.

The PANIC will also be eliminated by adding AMD vendor checking in
amd_gart_present:

+       if(boot_cpu_data.x86_vendor != X86_VENDOR_AMD)
+               return false;

To prevent the function return true on non AMD platform.

Thanks,
Pu Wen