RE: [PATCH 21/37] xen/arm: Keep memory nodes in dtb for NUMA when boot from EFI

[Wei Chen <Wei.Chen@arm.com>]

> -----Original Message-----
> From: Stefano Stabellini <sstabellini@kernel.org>
> Sent: 2021年9月24日 9:23
> To: Wei Chen <Wei.Chen@arm.com>
> Cc: xen-devel@lists.xenproject.org; sstabellini@kernel.org; julien@xen.org;
> Bertrand Marquis <Bertrand.Marquis@arm.com>
> Subject: Re: [PATCH 21/37] xen/arm: Keep memory nodes in dtb for NUMA when
> boot from EFI
> 
> On Thu, 23 Sep 2021, Wei Chen wrote:
> > EFI can get memory map from EFI system table. But EFI system
> > table doesn't contain memory NUMA information, EFI depends on
> > ACPI SRAT or device tree memory node to parse memory blocks'
> > NUMA mapping.
> >
> > But in current code, when Xen is booting from EFI, it will
> > delete all memory nodes in device tree. So in UEFI + DTB
> > boot, we don't have numa-node-id for memory blocks any more.
> >
> > So in this patch, we will keep memory nodes in device tree for
> > NUMA code to parse memory numa-node-id later.
> >
> > As a side effect, if we still parse boot memory information in
> > early_scan_node, bootmem.info will calculate memory ranges in
> > memory nodes twice. So we have to prevent early_scan_node to
> > parse memory nodes in EFI boot.
> >
> > As EFI APIs only can be used in Arm64, so we introduced a stub
> > API for non-EFI supported Arm32. This will prevent
> 
> This last sentence is incomplete.
> 
> But aside from that, this patch looks good to me.
> 

Ah, it truncated by accident. I will fix it.

> 
> > Signed-off-by: Wei Chen <wei.chen@arm.com>
> > ---
> >  xen/arch/arm/bootfdt.c      |  8 +++++++-
> >  xen/arch/arm/efi/efi-boot.h | 25 -------------------------
> >  xen/include/xen/efi.h       |  7 +++++++
> >  3 files changed, 14 insertions(+), 26 deletions(-)
> >
> > diff --git a/xen/arch/arm/bootfdt.c b/xen/arch/arm/bootfdt.c
> > index afaa0e249b..6bc5a465ec 100644
> > --- a/xen/arch/arm/bootfdt.c
> > +++ b/xen/arch/arm/bootfdt.c
> > @@ -11,6 +11,7 @@
> >  #include <xen/lib.h>
> >  #include <xen/kernel.h>
> >  #include <xen/init.h>
> > +#include <xen/efi.h>
> >  #include <xen/device_tree.h>
> >  #include <xen/libfdt/libfdt.h>
> >  #include <xen/sort.h>
> > @@ -370,7 +371,12 @@ static int __init early_scan_node(const void *fdt,
> >  {
> >      int rc = 0;
> >
> > -    if ( device_tree_node_matches(fdt, node, "memory") )
> > +    /*
> > +     * If Xen has been booted via UEFI, the memory banks will already
> > +     * be populated. So we should skip the parsing.
> > +     */
> > +    if ( !efi_enabled(EFI_BOOT) &&
> > +         device_tree_node_matches(fdt, node, "memory"))
> >          rc = process_memory_node(fdt, node, name, depth,
> >                                   address_cells, size_cells,
> &bootinfo.mem);
> >      else if ( depth == 1 && !dt_node_cmp(name, "reserved-memory") )
> > diff --git a/xen/arch/arm/efi/efi-boot.h b/xen/arch/arm/efi/efi-boot.h
> > index cf9c37153f..d0a9987fa4 100644
> > --- a/xen/arch/arm/efi/efi-boot.h
> > +++ b/xen/arch/arm/efi/efi-boot.h
> > @@ -197,33 +197,8 @@ EFI_STATUS __init
> fdt_add_uefi_nodes(EFI_SYSTEM_TABLE *sys_table,
> >      int status;
> >      u32 fdt_val32;
> >      u64 fdt_val64;
> > -    int prev;
> >      int num_rsv;
> >
> > -    /*
> > -     * Delete any memory nodes present.  The EFI memory map is the only
> > -     * memory description provided to Xen.
> > -     */
> > -    prev = 0;
> > -    for (;;)
> > -    {
> > -        const char *type;
> > -        int len;
> > -
> > -        node = fdt_next_node(fdt, prev, NULL);
> > -        if ( node < 0 )
> > -            break;
> > -
> > -        type = fdt_getprop(fdt, node, "device_type", &len);
> > -        if ( type && strncmp(type, "memory", len) == 0 )
> > -        {
> > -            fdt_del_node(fdt, node);
> > -            continue;
> > -        }
> > -
> > -        prev = node;
> > -    }
> > -
> >     /*
> >      * Delete all memory reserve map entries. When booting via UEFI,
> >      * kernel will use the UEFI memory map to find reserved regions.
> > diff --git a/xen/include/xen/efi.h b/xen/include/xen/efi.h
> > index 661a48286a..b52a4678e9 100644
> > --- a/xen/include/xen/efi.h
> > +++ b/xen/include/xen/efi.h
> > @@ -47,6 +47,13 @@ int efi_runtime_call(struct xenpf_efi_runtime_call *);
> >  int efi_compat_get_info(uint32_t idx, union compat_pf_efi_info *);
> >  int efi_compat_runtime_call(struct compat_pf_efi_runtime_call *);
> >
> > +#else
> > +
> > +static inline bool efi_enabled(unsigned int feature)
> > +{
> > +    return false;
> > +}
> > +
> >  #endif /* CONFIG_EFI*/
> >
> >  #endif /* !__ASSEMBLY__ */
> > --
> > 2.25.1
> >