Re: [PATCH] x86/numa: Add Devicetree support

[Saurabh Singh Sengar]

On Fri, Aug 11, 2023 at 10:29:57AM +0000, Saurabh Singh Sengar wrote:
> 
> 
> > -----Original Message-----
> > From: Michael Kelley (LINUX) <mikelley@xxxxxxxxxxxxx>
> > Sent: Thursday, August 3, 2023 12:19 AM
> > To: Saurabh Sengar <ssengar@xxxxxxxxxxxxxxxxxxx>; tglx@xxxxxxxxxxxxx;
> > mingo@xxxxxxxxxx; bp@xxxxxxxxx; dave.hansen@xxxxxxxxxxxxxxx;
> > x86@xxxxxxxxxx; hpa@xxxxxxxxx; luto@xxxxxxxxxx; peterz@xxxxxxxxxxxxx;
> > linux-kernel@xxxxxxxxxxxxxxx
> > Subject: [EXTERNAL] RE: [PATCH] x86/numa: Add Devicetree support
> > 
> > From: Saurabh Sengar <ssengar@xxxxxxxxxxxxxxxxxxx> Sent: Tuesday, June
> > 27, 2023 12:28 AM
> > >
> > > Hyper-V has usecases where it need to fetch NUMA information from
> > > Devicetree. Currently, it is not possible to extract the NUMA
> > > information from Devicetree for x86 arch.
> > >
> > > Add support for Devicetree in the x86_numa_init function, allowing the
> > > retrieval of NUMA node information from the Devicetree.
> > >
> > > Additionally, relocate the x86_dtb_init function before initmem_init
> > > to ensure the Devicetree initialization prior to its utilization in
> > > x86_numa_init.
> > >
> > > Signed-off-by: Saurabh Sengar <ssengar@xxxxxxxxxxxxxxxxxxx>
> > > ---
> > >  arch/x86/Kconfig        | 1 +
> > >  arch/x86/kernel/setup.c | 2 +-
> > >  arch/x86/mm/numa.c      | 3 +++
> > >  3 files changed, 5 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index
> > > c531b16ee0bf..a2ada193b2d8 100644
> > > --- a/arch/x86/Kconfig
> > > +++ b/arch/x86/Kconfig
> > > @@ -1567,6 +1567,7 @@ config NUMA
> > >  	depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
> > >  	default y if X86_BIGSMP
> > >  	select USE_PERCPU_NUMA_NODE_ID
> > > +	select OF_NUMA if OF
> > >  	help
> > >  	  Enable NUMA (Non-Uniform Memory Access) support.
> > >
> > > diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index
> > > fd975a4a5200..940c92a6a5e9 100644
> > > --- a/arch/x86/kernel/setup.c
> > > +++ b/arch/x86/kernel/setup.c
> > > @@ -1220,6 +1220,7 @@ void __init setup_arch(char **cmdline_p)
> > >
> > >  	early_acpi_boot_init();
> > >
> > > +	x86_dtb_init();
> > >  	initmem_init();
> > >  	dma_contiguous_reserve(max_pfn_mapped << PAGE_SHIFT);
> > >
> > > @@ -1261,7 +1262,6 @@ void __init setup_arch(char **cmdline_p)
> > >  	 * Read APIC and some other early information from ACPI tables.
> > >  	 */
> > >  	acpi_boot_init();
> > > -	x86_dtb_init();
> > >
> > >  	/*
> > >  	 * get boot-time SMP configuration:
> > > diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c index
> > > 2aadb2019b4f..a6d3d331fda2 100644
> > > --- a/arch/x86/mm/numa.c
> > > +++ b/arch/x86/mm/numa.c
> > > @@ -11,6 +11,7 @@
> > >  #include <linux/nodemask.h>
> > >  #include <linux/sched.h>
> > >  #include <linux/topology.h>
> > > +#include <linux/of.h>
> > >
> > >  #include <asm/e820/api.h>
> > >  #include <asm/proto.h>
> > > @@ -733,6 +734,8 @@ void __init x86_numa_init(void)
> > >  		if (!numa_init(amd_numa_init))
> > >  			return;
> > >  #endif
> > > +		if (acpi_disabled && !numa_init(of_numa_init))
> > > +			return;
> > >  	}
> > >
> > >  	numa_init(dummy_numa_init);
> > > --
> > > 2.34.1
> > 
> > This looks good to me.  I've looked and don't see any obvious issues in
> > moving x86_dtb_init() earlier in setup_arch().  But I also know the setup
> > ordering can be very tricky to get working correctly with a wide range of
> > platforms, and I don't have that expertise.
> > But with those caveats,
> > 
> > Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
> 
> Hi X86 Maintainers,
> 
> Is this good to be accepted ?

Thomas/Borislav,

Kind reminder to review this.

- Saurabh


> 
> - Saurabh