From: "Jonathan (Zhixiong) Zhang" zjzhang@codeaurora.org
On a platform with APEI (ACPI Platform Error Interface) enabled, firmware updates a memory region with hardware error record using nocache attribute. When OS reads the region, since it maps the region with cacahed attribute even though EFI memory map defines this region as uncached, OS gets stale data and errorneously reports there is no new HW error.
When ghes driver maps the memory region, it uses the cache attribute according to EFI memory map, if EFI memory map feature is enabled at runtime.
Since both arch/x86 and arc/ia64 implemented architecture agnostic EFI memory map attribue lookup function efi_memattributes(), the code is moved from arch/x86 and arch/ia64 into EFI subsystem. On top of that, efi_remap() is added.
V2: 1. Rebased to v4.1-rc5. 2. Split removal of efi_mem_attributes() and creation of efi_ioremap() into two patches.
Jonathan (Zhixiong) Zhang (3): efi: arch, x86: arch, ia64: move efi_mem_attributes() efi: add efi_remap() acpi, apei: use EFI memmap to map GHES memory
arch/ia64/kernel/efi.c | 11 ----------- arch/x86/platform/efi/efi.c | 18 ------------------ drivers/acpi/apei/ghes.c | 13 +++++++++++++ drivers/firmware/efi/efi.c | 27 +++++++++++++++++++++++++++ include/linux/efi.h | 1 + 5 files changed, 41 insertions(+), 29 deletions(-)