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

Dave Young posted 1 patch 11 months ago
[PATCH] x86/efi: skip memattr table on kexec boot
Posted by Dave Young 11 months ago
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
Posted by Ard Biesheuvel 11 months ago
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.