On 14.09.2021 11:41, Juergen Gross wrote:
> Commit a799c2bd29d19c565 ("x86/setup: Consolidate early memory
> reservations") introduced early_reserve_memory() to do all needed
> initial memblock_reserve() calls in one function. Unfortunately the
> call of early_reserve_memory() is done too late for Xen dom0, as in
> some cases a Xen hook called by e820__memory_setup() will need those
> memory reservations to have happened already.
>
> Move the call of early_reserve_memory() to the beginning of
> setup_arch() in order to avoid such problems.
>
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: a799c2bd29d19c565 ("x86/setup: Consolidate early memory reservations")
> Reported-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> ---
> arch/x86/kernel/setup.c | 24 ++++++++++++------------
> 1 file changed, 12 insertions(+), 12 deletions(-)
>
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index 79f164141116..f369c51ec580 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -757,6 +757,18 @@ dump_kernel_offset(struct notifier_block *self, unsigned long v, void *p)
>
> void __init setup_arch(char **cmdline_p)
> {
> + /*
> + * Do some memory reservations *before* memory is added to
> + * memblock, so memblock allocations won't overwrite it.
> + * Do it after early param, so we could get (unlikely) panic from
> + * serial.
Hmm, this part of the comment is not only stale now, but gets actively
undermined. No idea how likely such a panic() would be, and hence how
relevant it is to retain this particular property.
Jan
> + * After this point everything still needed from the boot loader or
> + * firmware or kernel text should be early reserved or marked not
> + * RAM in e820. All other memory is free game.
> + */
> + early_reserve_memory();
> +
> #ifdef CONFIG_X86_32
> memcpy(&boot_cpu_data, &new_cpu_data, sizeof(new_cpu_data));
>
> @@ -876,18 +888,6 @@ void __init setup_arch(char **cmdline_p)
>
> parse_early_param();
>
> - /*
> - * Do some memory reservations *before* memory is added to
> - * memblock, so memblock allocations won't overwrite it.
> - * Do it after early param, so we could get (unlikely) panic from
> - * serial.
> - *
> - * After this point everything still needed from the boot loader or
> - * firmware or kernel text should be early reserved or marked not
> - * RAM in e820. All other memory is free game.
> - */
> - early_reserve_memory();
> -
> #ifdef CONFIG_MEMORY_HOTPLUG
> /*
> * Memory used by the kernel cannot be hot-removed because Linux
>
