When this area is not reserved, it comes up as usable in /sys/firmware/memmap. This means that kexec, which uses that memmap to find usable memory regions, can select the region where efi_mem_attr_table is and overwrite it and relocate_kernel. Since the patch in [1] was merged, all boots after kexec are producing the warning that it introduced. Having a fix in firmware can be difficult to get through. The next ideal place would be in libstub. However, it looks like InstallMemoryAttributesTable [2] is not available as a boot service call option [3], [4], and install_configuration_table does not seem to work as a valid substitute. As a last option for a fix, this patch marks that region as reserved in e820_table_firmware if it is currently E820_TYPE_RAM so that kexec doesn't use it for kernel segments. [1] https://lore.kernel.org/all/20241031175822.2952471-2-ardb+git@xxxxxxxxxx/ [2] https://github.com/tianocore/edk2/blob/master/MdeModulePkg/Core/Dxe/Misc/MemoryAttributesTable.c#L100 [3] https://github.com/tianocore/edk2/blob/42a141800c0c26a09d2344e84a89ce4097a263ae/MdeModulePkg/Core/Dxe/DxeMain/DxeMain.c#L41 [4] https://elixir.bootlin.com/linux/v6.12.6/source/drivers/firmware/efi/libstub/efistub.h#L327 Reported-by: Breno Leitao <leitao@xxxxxxxxxx> Signed-off-by: Usama Arif <usamaarif642@xxxxxxxxx> --- arch/x86/include/asm/e820/api.h | 2 ++ arch/x86/kernel/e820.c | 6 ++++++ arch/x86/platform/efi/efi.c | 9 +++++++++ drivers/firmware/efi/memattr.c | 1 + include/linux/efi.h | 7 +++++++ 5 files changed, 25 insertions(+) diff --git a/arch/x86/include/asm/e820/api.h b/arch/x86/include/asm/e820/api.h index 2e74a7f0e935..4e9aa24f03bd 100644 --- a/arch/x86/include/asm/e820/api.h +++ b/arch/x86/include/asm/e820/api.h @@ -16,6 +16,8 @@ extern bool e820__mapped_all(u64 start, u64 end, enum e820_type type); extern void e820__range_add (u64 start, u64 size, enum e820_type type); extern u64 e820__range_update(u64 start, u64 size, enum e820_type old_type, enum e820_type new_type); +extern u64 e820__range_update_firmware(u64 start, u64 size, enum e820_type old_type, + enum e820_type new_type); extern u64 e820__range_remove(u64 start, u64 size, enum e820_type old_type, bool check_type); extern u64 e820__range_update_table(struct e820_table *t, u64 start, u64 size, enum e820_type old_type, enum e820_type new_type); diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c index 82b96ed9890a..01d7d3c0d299 100644 --- a/arch/x86/kernel/e820.c +++ b/arch/x86/kernel/e820.c @@ -538,6 +538,12 @@ u64 __init e820__range_update_table(struct e820_table *t, u64 start, u64 size, return __e820__range_update(t, start, size, old_type, new_type); } +u64 __init e820__range_update_firmware(u64 start, u64 size, enum e820_type old_type, + enum e820_type new_type) +{ + return __e820__range_update(e820_table_firmware, start, size, old_type, new_type); +} + /* Remove a range of memory from the E820 table: */ u64 __init e820__range_remove(u64 start, u64 size, enum e820_type old_type, bool check_type) { diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c index a7ff189421c3..13684c5d7c05 100644 --- a/arch/x86/platform/efi/efi.c +++ b/arch/x86/platform/efi/efi.c @@ -168,6 +168,15 @@ static void __init do_add_efi_memmap(void) e820__update_table(e820_table); } +/* Reserve firmware area if it was marked as RAM */ +void arch_update_firmware_area(u64 addr, u64 size) +{ + if (e820__get_entry_type(addr, addr + size) == E820_TYPE_RAM) { + e820__range_update_firmware(addr, size, E820_TYPE_RAM, E820_TYPE_RESERVED); + e820__update_table(e820_table_firmware); + } +} + /* * Given add_efi_memmap defaults to 0 and there is no alternative * e820 mechanism for soft-reserved memory, import the full EFI memory diff --git a/drivers/firmware/efi/memattr.c b/drivers/firmware/efi/memattr.c index d3bc161361fb..d131781e2d7b 100644 --- a/drivers/firmware/efi/memattr.c +++ b/drivers/firmware/efi/memattr.c @@ -53,6 +53,7 @@ int __init efi_memattr_init(void) size = tbl->num_entries * tbl->desc_size; tbl_size = sizeof(*tbl) + size; memblock_reserve(efi_mem_attr_table, tbl_size); + arch_update_firmware_area(efi_mem_attr_table, tbl_size); set_bit(EFI_MEM_ATTR, &efi.flags); unmap: diff --git a/include/linux/efi.h b/include/linux/efi.h index e5815867aba9..8eb9698bd6a4 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -1358,4 +1358,11 @@ extern struct blocking_notifier_head efivar_ops_nh; void efivars_generic_ops_register(void); void efivars_generic_ops_unregister(void); +#ifdef CONFIG_X86_64 +void __init arch_update_firmware_area(u64 addr, u64 size); +#else +static inline void __init arch_update_firmware_area(u64 addr, u64 size) +{ +} +#endif #endif /* _LINUX_EFI_H */ -- 2.43.5
