[PATCH] x86/efi: skip memattr table on kexec boot

[PATCH] x86/efi: skip memattr table on kexec boot

[Dave Young]

efi_memattr_init() added a sanity check to avoid firmware caused corruption.
The check is based on efi memmap entry numbers, but kexec only takes the
runtime related memmap entries thus this caused many false warnings, see
below thread for details:

https://lore.kernel.org/all/20250108215957.3437660-2-usamaarif642@gmail.com/

Ard suggests to skip the efi memattr table in kexec, this makes sense because
those memattr fixups are not critical.

Reported-by: Breno Leitao <leitao@debian.org>
Reported-and-tested-by: Usama Arif <usamaarif642@gmail.com>
Suggested-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Dave Young <dyoung@redhat.com>

diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c
index 846bf49f2508..553f330198f2 100644
--- a/arch/x86/platform/efi/quirks.c
+++ b/arch/x86/platform/efi/quirks.c
@@ -561,6 +561,11 @@ int __init efi_reuse_config(u64 tables, int nr_tables)
 
 		if (!efi_guidcmp(guid, SMBIOS_TABLE_GUID))
 			((efi_config_table_64_t *)p)->table = data->smbios;
+
+		/* Do not bother to play with mem attr table across kexec */
+		if (!efi_guidcmp(guid, EFI_MEMORY_ATTRIBUTES_TABLE_GUID))
+			((efi_config_table_64_t *)p)->table = EFI_INVALID_TABLE_ADDR;
+
 		p += sz;
 	}
 	early_memunmap(tablep, nr_tables * sz);

Re: [PATCH] x86/efi: skip memattr table on kexec boot

[Ard Biesheuvel]

On Thu, 23 Jan 2025 at 07:36, Dave Young <dyoung@redhat.com> wrote:
>
> efi_memattr_init() added a sanity check to avoid firmware caused corruption.
> The check is based on efi memmap entry numbers, but kexec only takes the
> runtime related memmap entries thus this caused many false warnings, see
> below thread for details:
>
> https://lore.kernel.org/all/20250108215957.3437660-2-usamaarif642@gmail.com/
>
> Ard suggests to skip the efi memattr table in kexec, this makes sense because
> those memattr fixups are not critical.
>
> Reported-by: Breno Leitao <leitao@debian.org>
> Reported-and-tested-by: Usama Arif <usamaarif642@gmail.com>
> Suggested-by: Ard Biesheuvel <ardb@kernel.org>
> Signed-off-by: Dave Young <dyoung@redhat.com>
>
> diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c
> index 846bf49f2508..553f330198f2 100644
> --- a/arch/x86/platform/efi/quirks.c
> +++ b/arch/x86/platform/efi/quirks.c
> @@ -561,6 +561,11 @@ int __init efi_reuse_config(u64 tables, int nr_tables)
>
>                 if (!efi_guidcmp(guid, SMBIOS_TABLE_GUID))
>                         ((efi_config_table_64_t *)p)->table = data->smbios;
> +
> +               /* Do not bother to play with mem attr table across kexec */
> +               if (!efi_guidcmp(guid, EFI_MEMORY_ATTRIBUTES_TABLE_GUID))
> +                       ((efi_config_table_64_t *)p)->table = EFI_INVALID_TABLE_ADDR;
> +
>                 p += sz;
>         }
>         early_memunmap(tablep, nr_tables * sz);
>

Thanks. I've queued this up now.