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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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