Messages in this thread | | | Date | Mon, 28 Sep 2020 15:00:55 +0100 | From | Will Deacon <> | Subject | Re: [PATCH] arm64: PCI: Validate the node before setting node id for root bus |
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[+ 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.
> 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.
Anyway, I defer to Lorenzo on this.
Will
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