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SubjectRe: [PATCH 01/11] x86/efi: Allocate e820 buffer before calling efi_exit_boot_service

* Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote:

> From: Eric Snowberg <eric.snowberg@oracle.com>
>
> Commit d64934019f6c ("x86/efi: Use efi_exit_boot_services()")
> introduced a regression on systems with large memory maps
> causing them to hang on boot. The first "goto get_map" that was removed
> from exit_boot insured there was enough room for the memory map when
> efi_call_early(exit_boot_services) was called. This happens when
> (nr_desc > ARRAY_SIZE(params->e820_table).
>
> Chain of events:
> exit_boot()
> efi_exit_boot_services()
> efi_get_memory_map <- at this point the mm can't grow over 8 desc
> priv_func()
> exit_boot_func()
> allocate_e820ext() <- new mm grows over 8 desc from e820 alloc
> efi_call_early(exit_boot_services) <- mm key doesn't match so retry
> efi_call_early(get_memory_map) <- not enough room for new mm
> system hangs
>
> This patch allocates the e820 buffer before calling efi_exit_boot_services
> and fixes the regression.
>
> Signed-off-by: Eric Snowberg <eric.snowberg@oracle.com>
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> ---
> arch/x86/boot/compressed/eboot.c | 65 ++++++++++++++++++++------------
> 1 file changed, 41 insertions(+), 24 deletions(-)

Any objections against marking this for -stable and filing it in
efi/urgent? Boot hangs are show-stopper bugs, so distributions would want
to backport this fix anyway.

> + boot_map.map = &map;
> + boot_map.map_size = &map_size;
> + boot_map.desc_size = &desc_size;
> + boot_map.desc_ver = NULL;
> + boot_map.key_ptr = NULL;
> + boot_map.buff_size = &buff_size;

I have changed this to the canonical style, which is also used elsewhere
in the file:

> map.buff_size = &buff_size;
> priv.boot_params = boot_params;
> priv.efi = &boot_params->efi_info;
> - priv.e820ext = NULL;
> - priv.e820ext_size = 0;

I.e.:

+ boot_map.map = &map;
+ boot_map.map_size = &map_size;
+ boot_map.desc_size = &desc_size;
+ boot_map.desc_ver = NULL;
+ boot_map.key_ptr = NULL;
+ boot_map.buff_size = &buff_size;
+
+ status = efi_get_memory_map(sys_table, &boot_map);

Thanks,

Ingo

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