Messages in this thread | | | Date | Mon, 28 Sep 2020 22:49:57 +0800 | From | Baolin Wang <> | Subject | Re: [PATCH] arm64: PCI: Validate the node before setting node id for root bus |
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On Mon, Sep 28, 2020 at 03:00:55PM +0100, Will Deacon wrote: > [+ Lorenzo] > > On Tue, Sep 22, 2020 at 06:33:24PM +0800, Baolin Wang wrote: > > If the BIOS disabled the NUMA configuration, but did not change the > > proximity domain description in the SRAT table, so the PCI root bus > > device may get a incorrect node id by acpi_get_node(). > > How "incorrect" are we talking here? What actually goes wrong? At some > point, we have to trust what the firmware is telling us.
What I mean is, if we disable the NUMA from BIOS, but we did not change the PXM for the PCI devices, so the PCI devices can still get a numa node id from acpi_get_node(). For example, we can still get the numa node id = 1 in this case from acpi_get_node(), but the numa_nodes_parsed is empty, which means the node id 1 is invalid. We should add a validation for the node id when setting the root bus node id.
> > > Thus better to add a numa node validation before setting numa node > > for the PCI root bus, like pci_acpi_root_get_node() does for X86 > > architecture. > > > > Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> > > --- > > arch/arm64/kernel/pci.c | 6 +++++- > > 1 file changed, 5 insertions(+), 1 deletion(-) > > > > diff --git a/arch/arm64/kernel/pci.c b/arch/arm64/kernel/pci.c > > index 1006ed2..24fe2bd 100644 > > --- a/arch/arm64/kernel/pci.c > > +++ b/arch/arm64/kernel/pci.c > > @@ -86,9 +86,13 @@ int pcibios_root_bridge_prepare(struct pci_host_bridge *bridge) > > struct pci_config_window *cfg = bridge->bus->sysdata; > > struct acpi_device *adev = to_acpi_device(cfg->parent); > > struct device *bus_dev = &bridge->bus->dev; > > + int node = acpi_get_node(acpi_device_handle(adev)); > > + > > + if (node != NUMA_NO_NODE && !node_online(node)) > > + node = NUMA_NO_NODE; > > Hmm. afaict, acpi_get_node() tries quite hard to return a valid node when > it gets back NUMA_NO_NODE in acpi_map_pxm_to_node(). Seems like we're > undoing all of that here, which worries me because NUMA_NO_NODE is a bit > of a loaded gun if you interpret it as a valid node.
I did not treate NUMA_NO_NODE as a valid node, I just add a validation to validate if it is a valid node before setting. See my previous comments, hopes I make things clear. Thanks.
> > Anyway, I defer to Lorenzo on this. > > Will
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