RE: [Patch v3] PCI: hv: Fix NUMA node assignment when kernel boots with custom NUMA topology

[Long Li <longli@microsoft.com>]

> Subject: Re: [Patch v3] PCI: hv: Fix NUMA node assignment when kernel boots
> with custom NUMA topology
> 
> On Wed, Jan 19, 2022 at 11:59:06AM -0800, longli@linuxonhyperv.com wrote:
> > From: Long Li <longli@microsoft.com>
> >
> > When kernel boots with a NUMA topology with some NUMA nodes offline,
> > the PCI driver should only set an online NUMA node on the device. This
> > can happen during KDUMP where some NUMA nodes are not made online by
> the KDUMP kernel.
> >
> > This patch also fixes the case where kernel is booting with "numa=off".
> >
> > Fixes: 999dd956d838 ("PCI: hv: Add support for protocol 1.3 and
> > support PCI_BUS_RELATIONS2")
> >
> 
> No blank line here, please
> 
> > Signed-off-by: Long Li <longli@microsoft.com>
> 
> Everything below needs to be under "---" marker.

I'm sending v4 to address the comments.

Long


> 
> Thanks
> 
> >
> > Change log:
> > v2: use numa_map_to_online_node() to assign a node to device
> > (suggested by Michael Kelly <mikelley@microsoft.com>)
> >
> > v3: add "Fixes" and check for num_possible_nodes()
> > ---
> >  drivers/pci/controller/pci-hyperv.c | 13 +++++++++++--
> >  1 file changed, 11 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/pci/controller/pci-hyperv.c
> > b/drivers/pci/controller/pci-hyperv.c
> > index 6c9efeefae1b..b5276e81bb44 100644
> > --- a/drivers/pci/controller/pci-hyperv.c
> > +++ b/drivers/pci/controller/pci-hyperv.c
> > @@ -2129,8 +2129,17 @@ static void hv_pci_assign_numa_node(struct
> hv_pcibus_device *hbus)
> >  		if (!hv_dev)
> >  			continue;
> >
> > -		if (hv_dev->desc.flags &
> HV_PCI_DEVICE_FLAG_NUMA_AFFINITY)
> > -			set_dev_node(&dev->dev, hv_dev-
> >desc.virtual_numa_node);
> > +		if (hv_dev->desc.flags &
> HV_PCI_DEVICE_FLAG_NUMA_AFFINITY &&
> > +		    hv_dev->desc.virtual_numa_node < num_possible_nodes())
> > +			/*
> > +			 * The kernel may boot with some NUMA nodes offline
> > +			 * (e.g. in a KDUMP kernel) or with NUMA disabled via
> > +			 * "numa=off". In those cases, adjust the host provided
> > +			 * NUMA node to a valid NUMA node used by the kernel.
> > +			 */
> > +			set_dev_node(&dev->dev,
> > +				     numa_map_to_online_node(
> > +					     hv_dev->desc.virtual_numa_node));
> >
> >  		put_pcichild(hv_dev);
> >  	}
> > --
> > 2.25.1
> >