ACPI: Add memory semantics to acpi_os_map_memory()

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.

Link: https://lore.kernel.org/linux-arm-kernel/31ffe8fc-f5ee-2858-26c5-0fd8bdd68702@arm.com
Tested-by: Hanjun Guo <guohanjun@huawei.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

2 files changed, 19 insertions, 3 deletions

diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h
index bd68e1b7f29f..7535dc7cc5aa 100644
--- a/arch/arm64/include/asm/acpi.h
+++ b/arch/arm64/include/asm/acpi.h
@@ -50,6 +50,9 @@ pgprot_t __acpi_get_mem_attribute(phys_addr_t addr);
 void __iomem *acpi_os_ioremap(acpi_physical_address phys, acpi_size size);
 #define acpi_os_ioremap acpi_os_ioremap
 
+void __iomem *acpi_os_memmap(acpi_physical_address phys, acpi_size size);
+#define acpi_os_memmap acpi_os_memmap
+
 typedef u64 phys_cpuid_t;
 #define PHYS_CPUID_INVALID INVALID_HWID
 
diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
index f3851724fe35..1c9c2f7a1c04 100644
--- a/arch/arm64/kernel/acpi.c
+++ b/arch/arm64/kernel/acpi.c
@@ -273,7 +273,8 @@ pgprot_t __acpi_get_mem_attribute(phys_addr_t addr)
 	return __pgprot(PROT_DEVICE_nGnRnE);
 }
 
-void __iomem *acpi_os_ioremap(acpi_physical_address phys, acpi_size size)
+static void __iomem *__acpi_os_ioremap(acpi_physical_address phys,
+				       acpi_size size, bool memory)
 {
 	efi_memory_desc_t *md, *region = NULL;
 	pgprot_t prot;
@@ -299,9 +300,11 @@ void __iomem *acpi_os_ioremap(acpi_physical_address phys, acpi_size size)
 	 * It is fine for AML to remap regions that are not represented in the
 	 * EFI memory map at all, as it only describes normal memory, and MMIO
 	 * regions that require a virtual mapping to make them accessible to
-	 * the EFI runtime services.
+	 * the EFI runtime services. Determine the region default
+	 * attributes by checking the requested memory semantics.
 	 */
-	prot = __pgprot(PROT_DEVICE_nGnRnE);
+	prot = memory ? __pgprot(PROT_NORMAL_NC) :
+			__pgprot(PROT_DEVICE_nGnRnE);
 	if (region) {
 		switch (region->type) {
 		case EFI_LOADER_CODE:
@@ -361,6 +364,16 @@ void __iomem *acpi_os_ioremap(acpi_physical_address phys, acpi_size size)
 	return __ioremap(phys, size, prot);
 }
 
+void __iomem *acpi_os_ioremap(acpi_physical_address phys, acpi_size size)
+{
+	return __acpi_os_ioremap(phys, size, false);
+}
+
+void __iomem *acpi_os_memmap(acpi_physical_address phys, acpi_size size)
+{
+	return __acpi_os_ioremap(phys, size, true);
+}
+
 /*
  * Claim Synchronous External Aborts as a firmware first notification.
  *