Hey all, After some consideration, I've decided to post a v2 of this patch that will make it a bit safer (although I haven't seen any problems with it) and make it a little easier to refactor some of the EEH code that interacts with the hooks.
Cheers,
Sam.
On Thu, Feb 14, 2019 at 04:14:42PM +1100, Sam Bobroff wrote:
> The pcibios_init() function for 64 bit PowerPC currently calls
> pci_bus_add_devices() before pcibios_resource_survey(), which seems
> incorrect because it adds devices and attempts to bind their drivers
> before allocating their resources (although no problems seem to be
> apparent).
>
> So move the call to pci_bus_add_devices() to after
> pcibios_resource_survey().
>
> This will also allow the ppc_md.pcibios_bus_add_device() hooks to
> perform actions that depend on PCI resources, both during rescanning
> (where this is already the case) and at boot time, which should
> support improvements and refactoring.
>
> Signed-off-by: Sam Bobroff <sbobr...@linux.ibm.com>
> ---
> Hi everyone,
>
> I've tested this on a P9 for both the host and a KVM guest, and the change
> hasn't caused any differences in PCI resource assignments or the general boot
> messages.
>
> I've also had a go at inspecting most of the code used by
> pci_bus_add_devices()
> and pcibios_resource_survey() and it doesn't look like there are going to be
> any changes in behaviour caused by reordering. It might be worth mentioning
> that the hotplug path (see pcibios_finish_adding_to_bus()) already does
> resource allocation before calling pci_bus_add_devices().
>
> However, it would be great if someone could test this change on some older
> hardware or comment on wether we should make the same change on 32 bit
> machines.
>
> Cheers,
> Sam.
>
> arch/powerpc/kernel/pci_64.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/arch/powerpc/kernel/pci_64.c b/arch/powerpc/kernel/pci_64.c
> index 9d8c10d55407..1ce28888dbdb 100644
> --- a/arch/powerpc/kernel/pci_64.c
> +++ b/arch/powerpc/kernel/pci_64.c
> @@ -58,14 +58,16 @@ static int __init pcibios_init(void)
> pci_add_flags(PCI_ENABLE_PROC_DOMAINS | PCI_COMPAT_DOMAIN_0);
>
> /* Scan all of the recorded PCI controllers. */
> - list_for_each_entry_safe(hose, tmp, &hose_list, list_node) {
> + list_for_each_entry_safe(hose, tmp, &hose_list, list_node)
> pcibios_scan_phb(hose);
> - pci_bus_add_devices(hose->bus);
> - }
>
> /* Call common code to handle resource allocation */
> pcibios_resource_survey();
>
> + /* Add devices. */
> + list_for_each_entry_safe(hose, tmp, &hose_list, list_node)
> + pci_bus_add_devices(hose->bus);
> +
> printk(KERN_DEBUG "PCI: Probing PCI hardware done\n");
>
> return 0;
> --
> 2.19.0.2.gcad72f5712
>
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