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

[Saurabh Singh Sengar]

> -----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 ?

- Saurabh