Re: [Xen-devel] [PATCH 6/8] x86/setup: move vm_init() before end_boot_allocator()

["Xia, Hongyan" <hongyxia@xxxxxxxxxx>]

On Sat, 2020-02-01 at 00:33 +0000, David Woodhouse wrote:
> From: David Woodhouse <dwmw@xxxxxxxxxxxx>
> 
> We would like to be able to use vmap() to map the live update data,
> and
> we need to do a first pass of the live update data before we prime
> the
> heap because we need to know which pages need to be preserved.
> 
> The warning about ACPI code can be dropped, since that problem no
> longer
> exists when things are done in this order.
> 
> Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx>
> ---
>  xen/arch/x86/setup.c | 8 ++------
>  1 file changed, 2 insertions(+), 6 deletions(-)
> 
> diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
> index 2677f127b9..5f68a1308f 100644
> --- a/xen/arch/x86/setup.c
> +++ b/xen/arch/x86/setup.c
> @@ -1489,6 +1489,8 @@ void __init noreturn __start_xen(unsigned long
> mbi_p)
>  
>      numa_initmem_init(0, raw_max_page);
>  
> +    vm_init();
> +
>      if ( max_page - 1 > virt_to_mfn(HYPERVISOR_VIRT_END - 1) )
>      {
>          unsigned long limit = virt_to_mfn(HYPERVISOR_VIRT_END - 1);
> @@ -1519,12 +1521,6 @@ void __init noreturn __start_xen(unsigned long
> mbi_p)
>          end_boot_allocator();
>  
>      system_state = SYS_STATE_boot;
> -    /*
> -     * No calls involving ACPI code should go between the setting of
> -     * SYS_STATE_boot and vm_init() (or else
> acpi_os_{,un}map_memory()
> -     * will break).
> -     */
> -    vm_init();
>  
>      console_init_ring();
>      vesa_init();

Is there any problem to move vm_init() even earlier than this, like
right after init_frametable()? ACPI and NUMA functions need a couple of
things permanently mapped. Without the directmap (directmap removal
series), xenheap and vmap at this stage, I can only map memory to the
directmap region which is really hacky. I would like to use vmap at
this stage so hopefully vmap can be ready very early.

Hongyan
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