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Subject[RFT][PATCH v2 4/4] ACPI: OSL: Implement acpi_os_map_memory_fast_path()
Date
From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>

Add acpi_os_map_memory_fast_path() and set ACPI_USE_FAST_PATH_MAPPING
to allow acpi_ex_system_memory_space_handler() to avoid unnecessary
memory mapping and unmapping overhead by retaining all memory
mappings created by it until the memory opregions associated with
them go away.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
drivers/acpi/osl.c | 65 +++++++++++++++++++++++--------
include/acpi/platform/aclinuxex.h | 4 ++
2 files changed, 53 insertions(+), 16 deletions(-)

diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index 28863d908fa8..89554ec9a178 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -306,21 +306,8 @@ static void acpi_unmap(acpi_physical_address pg_off, void __iomem *vaddr)
iounmap(vaddr);
}

-/**
- * 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.
- *
- * 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
- * virtual address). If not found, map it, add it to that list and return a
- * pointer to it.
- *
- * 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 fast_path)
{
struct acpi_ioremap *map;
void __iomem *virt;
@@ -332,8 +319,12 @@ void __iomem __ref
return NULL;
}

- if (!acpi_permanent_mmap)
+ if (!acpi_permanent_mmap) {
+ if (WARN_ON(fast_path))
+ return NULL;
+
return __acpi_map_table((unsigned long)phys, size);
+ }

mutex_lock(&acpi_ioremap_lock);
/* Check if there's a suitable mapping already. */
@@ -343,6 +334,11 @@ void __iomem __ref
goto out;
}

+ if (fast_path) {
+ mutex_unlock(&acpi_ioremap_lock);
+ return NULL;
+ }
+
map = kzalloc(sizeof(*map), GFP_KERNEL);
if (!map) {
mutex_unlock(&acpi_ioremap_lock);
@@ -370,6 +366,25 @@ void __iomem __ref
mutex_unlock(&acpi_ioremap_lock);
return map->virt + (phys - map->phys);
}
+
+/**
+ * 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.
+ *
+ * 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 representing
+ * its virtual address. If not found, map it, add it to that list and return a
+ * pointer representing its virtual address.
+ *
+ * During early init (when acpi_permanent_mmap has not been set yet) call
+ * __acpi_map_table() to obtain the mapping.
+ */
+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)
@@ -378,6 +393,24 @@ void *__ref acpi_os_map_memory(acpi_physical_address phys, acpi_size size)
}
EXPORT_SYMBOL_GPL(acpi_os_map_memory);

+/**
+ * acpi_os_map_memory_fast_path - Fast-path physical-to-virtual address mapping.
+ * @phys: Start of the physical address range to map.
+ * @size: Size of the physical address range to map.
+ *
+ * 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 representing
+ * its virtual address. If not found, return NULL.
+ *
+ * During early init (when acpi_permanent_mmap has not been set yet) log a
+ * warning and return NULL.
+ */
+void __ref *acpi_os_map_memory_fast_path(acpi_physical_address phys,
+ acpi_size size)
+{
+ return __acpi_os_map_iomem(phys, size, true);
+}
+
/* Must be called with mutex_lock(&acpi_ioremap_lock) */
static bool acpi_os_drop_map_ref(struct acpi_ioremap *map, bool defer)
{
diff --git a/include/acpi/platform/aclinuxex.h b/include/acpi/platform/aclinuxex.h
index e13f364d6c69..89c387449425 100644
--- a/include/acpi/platform/aclinuxex.h
+++ b/include/acpi/platform/aclinuxex.h
@@ -143,6 +143,10 @@ void acpi_os_release_unused_mappings(void);

#define ACPI_USE_DEFERRED_UNMAPPING

+void *acpi_os_map_memory_fast_path(acpi_physical_address where, acpi_size length);
+
+#define ACPI_USE_FAST_PATH_MAPPING
+
#endif /* __KERNEL__ */

#endif /* __ACLINUXEX_H__ */
--
2.26.2



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