[PATCH v2 3/3] ACPI: Add memory semantics to acpi_os_map_memory()

[Lorenzo Pieralisi]

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@xxxxxxx
Tested-by: Hanjun Guo <guohanjun@xxxxxxxxxx>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
Acked-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
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 ++++++++
 4 files changed, 43 insertions(+), 10 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.
  *
diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index fdee0c6f4f7f..2fcd3bb9a3c1 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -284,7 +284,8 @@ acpi_map_lookup_virt(void __iomem *virt, acpi_size size)
 #define should_use_kmap(pfn)   page_is_ram(pfn)
 #endif
 
-static void __iomem *acpi_map(acpi_physical_address pg_off, unsigned long pg_sz)
+static void __iomem *acpi_map(acpi_physical_address pg_off, unsigned long pg_sz,
+			      bool memory)
 {
 	unsigned long pfn;
 
@@ -294,7 +295,8 @@ static void __iomem *acpi_map(acpi_physical_address pg_off, unsigned long pg_sz)
 			return NULL;
 		return (void __iomem __force *)kmap(pfn_to_page(pfn));
 	} else
-		return acpi_os_ioremap(pg_off, pg_sz);
+		return memory ? acpi_os_memmap(pg_off, pg_sz) :
+				acpi_os_ioremap(pg_off, pg_sz);
 }
 
 static void acpi_unmap(acpi_physical_address pg_off, void __iomem *vaddr)
@@ -309,9 +311,10 @@ static void acpi_unmap(acpi_physical_address pg_off, void __iomem *vaddr)
 }
 
 /**
- * acpi_os_map_iomem - Get a virtual address for a given physical address range.
+ * __acpi_os_map_iomem - Get a virtual address for a given physical address range.
  * @phys: Start of the physical address range to map.
  * @size: Size of the physical address range to map.
+ * @memory: true if remapping memory, false if IO
  *
  * Look up the given physical address range in the list of existing ACPI memory
  * mappings.  If found, get a reference to it and return a pointer to it (its
@@ -321,8 +324,8 @@ static void acpi_unmap(acpi_physical_address pg_off, void __iomem *vaddr)
  * During early init (when acpi_permanent_mmap has not been set yet) this
  * routine simply calls __acpi_map_table() to get the job done.
  */
-void __iomem *__ref
-acpi_os_map_iomem(acpi_physical_address phys, acpi_size size)
+static void __iomem *__ref
+__acpi_os_map_iomem(acpi_physical_address phys, acpi_size size, bool memory)
 {
 	struct acpi_ioremap *map;
 	void __iomem *virt;
@@ -353,7 +356,7 @@ acpi_os_map_iomem(acpi_physical_address phys, acpi_size size)
 
 	pg_off = round_down(phys, PAGE_SIZE);
 	pg_sz = round_up(phys + size, PAGE_SIZE) - pg_off;
-	virt = acpi_map(phys, size);
+	virt = acpi_map(phys, size, memory);
 	if (!virt) {
 		mutex_unlock(&acpi_ioremap_lock);
 		kfree(map);
@@ -372,11 +375,17 @@ acpi_os_map_iomem(acpi_physical_address phys, acpi_size size)
 	mutex_unlock(&acpi_ioremap_lock);
 	return map->virt + (phys - map->phys);
 }
+
+void __iomem *__ref
+acpi_os_map_iomem(acpi_physical_address phys, acpi_size size)
+{
+	return __acpi_os_map_iomem(phys, size, false);
+}
 EXPORT_SYMBOL_GPL(acpi_os_map_iomem);
 
 void *__ref acpi_os_map_memory(acpi_physical_address phys, acpi_size size)
 {
-	return (__force void *)acpi_os_map_iomem(phys, size);
+	return (__force void *)__acpi_os_map_iomem(phys, size, true);
 }
 EXPORT_SYMBOL_GPL(acpi_os_map_memory);
 
diff --git a/include/acpi/acpi_io.h b/include/acpi/acpi_io.h
index a0094420303f..b69a2a1c144c 100644
--- a/include/acpi/acpi_io.h
+++ b/include/acpi/acpi_io.h
@@ -14,6 +14,14 @@ static inline void __iomem *acpi_os_ioremap(acpi_physical_address phys,
 }
 #endif
 
+#ifndef acpi_os_memmap
+static inline void __iomem *acpi_os_memmap(acpi_physical_address phys,
+					    acpi_size size)
+{
+	return ioremap_cache(phys, size);
+}
+#endif
+
 extern bool acpi_permanent_mmap;
 
 void __iomem *__ref
-- 
2.31.0