linux/drivers/firmware/efi
Ard Biesheuvel e7761d827e efi/unaccepted: Use ACPI reclaim memory for unaccepted memory table
Kyril reports that crashkernels fail to work on confidential VMs that
rely on the unaccepted memory table, and this appears to be caused by
the fact that it is not considered part of the set of firmware tables
that the crashkernel needs to map.

This is an oversight, and a result of the use of the EFI_LOADER_DATA
memory type for this table. The correct memory type to use for any
firmware table is EFI_ACPI_RECLAIM_MEMORY (including ones created by the
EFI stub), even though the name suggests that is it specific to ACPI.
ACPI reclaim means that the memory is used by the firmware to expose
information to the operating system, but that the memory region has no
special significance to the firmware itself, and the OS is free to
reclaim the memory and use it as ordinary memory if it is not interested
in the contents, or if it has already consumed them. In Linux, this
memory is never reclaimed, but it is always covered by the kernel direct
map and generally made accessible as ordinary memory.

On x86, ACPI reclaim memory is translated into E820_ACPI, which the
kexec logic already recognizes as memory that the crashkernel may need
to to access, and so it will be mapped and accessible to the booting
crash kernel.

Fixes: 745e3ed85f ("efi/libstub: Implement support for unaccepted memory")
Reported-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2023-09-11 06:37:51 +00:00
..
libstub efi/unaccepted: Use ACPI reclaim memory for unaccepted memory table 2023-09-11 06:37:51 +00:00
test efi/efi_test: read RuntimeServicesSupported 2020-12-09 08:37:27 +01:00
apple-properties.c efi: fix return value of __setup handlers 2022-03-01 09:02:21 +01:00
arm-runtime.c ARM updates for 6.2 2022-12-13 15:22:14 -08:00
capsule-loader.c efi: capsule-loader: Fix use-after-free in efi_capsule_write 2022-09-07 18:23:56 +02:00
capsule.c efi: capsule: clean scatter-gather entries from the D-cache 2020-12-09 08:37:27 +01:00
cper_cxl.c efi/cper, cxl: Remove cxl_err.h 2023-02-03 23:59:58 +01:00
cper_cxl.h efi/cper, cxl: Decode CXL Protocol Error Section 2022-11-18 09:14:10 +01:00
cper-arm.c efi/cper: Remove unnecessary aer.h include 2023-04-07 16:42:31 -05:00
cper-x86.c x86/mce, cper: Pass x86 CPER through the MCA handling chain 2020-11-21 12:05:41 +01:00
cper.c EFI updates for v6.2: 2022-12-13 14:31:47 -08:00
dev-path-parser.c efi/dev-path-parser: Refactor _UID handling to use acpi_dev_uid_to_integer() 2022-09-19 18:34:42 +02:00
earlycon.c efi: earlycon: Reprobe after parsing config tables 2023-03-13 23:28:43 +01:00
efi-bgrt.c
efi-init.c efi: earlycon: Reprobe after parsing config tables 2023-03-13 23:28:43 +01:00
efi-pstore.c EFI updates for v6.2: 2022-12-13 14:31:47 -08:00
efi.c EFI updates for v6.5 2023-06-30 21:35:52 -07:00
efibc.c efi: efibc: Guard against allocation failure 2022-09-20 18:42:55 +02:00
embedded-firmware.c crypto: sha - split sha.h into sha1.h and sha2.h 2020-11-20 14:45:33 +11:00
esrt.c efi/esrt: Allow ESRT access without CAP_SYS_ADMIN 2023-06-06 15:33:59 +02:00
fdtparams.c efi: xen: Set EFI_PARAVIRT for Xen dom0 boot on all architectures 2022-11-18 09:14:09 +01:00
Kconfig efi/libstub: Implement support for unaccepted memory 2023-06-06 16:58:23 +02:00
Makefile efi: Add unaccepted memory support 2023-06-06 17:22:20 +02:00
memattr.c A healthy mix of EFI contributions this time: 2023-02-23 14:41:48 -08:00
memmap.c efi: xen: Set EFI_PARAVIRT for Xen dom0 boot on all architectures 2022-11-18 09:14:09 +01:00
mokvar-table.c efi/mokvar: move up init order 2022-03-08 13:55:52 +02:00
rci2-table.c
reboot.c efi: Fix efi_power_off() not being run before acpi_power_off() when necessary 2022-07-10 17:41:06 +02:00
riscv-runtime.c efi/riscv: Move EFI runtime call setup/teardown helpers out of line 2023-08-21 17:59:25 +02:00
runtime-wrappers.c efi/runtime-wrappers: Clean up white space and add __init annotation 2023-08-22 10:39:26 +02:00
sysfb_efi.c efi: sysfb_efi: Add quirk for Lenovo Yoga Book X91F/L 2023-03-18 11:44:57 +01:00
tpm.c efi/tpm: Pass correct address to memblock_reserve 2022-10-24 08:04:25 +02:00
unaccepted_memory.c efi/unaccepted: Avoid load_unaligned_zeropad() stepping into unaccepted memory 2023-06-06 17:27:08 +02:00
vars.c efivarfs: expose used and total size 2023-05-17 18:21:34 +02:00