Re: [PATCH] ACPI: Add memory semantics to acpi_os_map_memory()

From: Hanjun Guo
Date: Tue Jul 27 2021 - 00:21:53 EST

On 2021/7/26 18:00, Lorenzo Pieralisi wrote:
The memory attributes attached to memory regions depend on architecture
specific mappings.

For some memory regions, the attributes specified by firmware (eg
uncached) are not sufficient to determine how a memory region should be
mapped by an OS (for instance a region that is define as uncached in
firmware can be mapped as Normal or Device memory on arm64) and
therefore the OS must be given control on how to map the region to match
the expected mapping behaviour (eg if a mapping is requested with memory
semantics, it must allow unaligned accesses).

Rework acpi_os_map_memory() and acpi_os_ioremap() back-end to split
them into two separate code paths:

acpi_os_memmap() -> memory semantics
acpi_os_ioremap() -> MMIO semantics

The split allows the architectural implementation back-ends to detect
the default memory attributes required by the mapping in question
(ie the mapping API defines the semantics memory vs MMIO) and map the
memory accordingly.

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
Cc: Ard Biesheuvel <ardb@xxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Hanjun Guo <guohanjun@xxxxxxxxxx>
Cc: Sudeep Holla <sudeep.holla@xxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>
arch/arm64/include/asm/acpi.h | 3 +++
arch/arm64/kernel/acpi.c | 19 ++++++++++++++++---
drivers/acpi/osl.c | 23 ++++++++++++++++-------
include/acpi/acpi_io.h | 8 ++++++++

Acked-by: Hanjun Guo <guohanjun@xxxxxxxxxx>

I did the boot test on both x86 and ARM64 server machines,
and no regressions,

Tested-by: Hanjun Guo <guohanjun@xxxxxxxxxx>